Zhang, Junliang (Stony Brook, NY, US)
Sasaki, Kotaro (Ronkonkoma, NY, US)
Mo, Yibo (Naperville, IL, US)
Vukmirovic, Miomir (Port Jefferson Station, NY, US)
Plaque It!
Sponsored by: Flash of Genius |
2. The particle composite according to claim 1, wherein said atomically thin layer of platinum atoms is selected from the group consisting of an atomic submonolayer, monolayer, bilayer, trilayer, and combinations thereof, of platinum atoms.
3. The particle composite according to claim 1, wherein said particle composite comprises a palladium alloy core coated with an atomically thin layer of platinum atoms.
4. The particle composite according to claim 3, wherein said palladium alloy core is comprised of a homogeneous combination of palladium and an alloying metal.
5. A particle composite according to claim 4, wherein said alloying metal is a transition metal.
6. The particle composite according to claim 5, wherein said transition metal is a first row transition metal.
7. The particle composite according to claim 6, wherein said transition metal is selected from the group consisting of iron, cobalt, nickel, and combinations thereof.
8. The particle composite according to claim 3, wherein said palladium alloy is comprised of a heterogeneous combination of palladium and an alloying metal.
9. The particle composite according to claim 8, wherein said heterogeneous combination is comprised of an inner core of alloying metal coated with a layer of palladium.
10. A particle composite according to claim 1 further comprising metal-bonding ligands or surfactants on said surface layer of zerovalent platinum.
11. The particle composite according to claim 1, wherein said particle composite has a size of about three to ten nanometers.
12. The particle composite according to claim 11, wherein said particle composite has a size of about five nanometers.
13. The particle composite according to claim 1, wherein said palladium or palladium alloy core is coated with an atomic submonolayer of zerovalent platinum atoms.
14. The particle composite according to claim 13, wherein said atomic submonolayer of zerovalent platinum atoms is in combination with a submonolayer of one or a combination of metals other than platinum, thereby providing a platinum-metal alloy monolayer.
15. The particle composite according to claim 14, wherein the metal other than platinum is a transition metal.
16. The particle composite according to claim 15, wherein the transition metal is Ir, Ru, Os, or Re.
17. The particle composite according to claim 16, wherein said platinum-metal alloy monolayer is according to the formula Ir0.2Pt0.8.
18. The particle composite according to claim 16, wherein said platinum-metal alloy monolayer is according to the formula Ru0.2Pt0.8.
19. The particle composite according to claim 16, wherein said platinum-metal alloy monolayer is according to the formula Os0.2Pt0.8.
20. The particle composite according to claim 16, wherein said platinum-metal alloy monolayer is according to the formula Re0.2Pt0.8.
21. A suspension or dispersion comprising a particle composite suspended or dispersed in a liquid phase, said particle composite comprising a palladium or palladium alloy core coated with an atomically thin layer of zerovalent platinum atoms.
22. A catalyst comprising a particle composite bound to a support, said particle composite comprising a palladium or palladium alloy core coated with an atomically thin layer of zerovalent platinum atoms
23. The catalyst according to claim 22, wherein said support is selected from the group consisting of carbon black, graphitized carbon, graphite, activated carbon, alumina, silica, silica-alumina, titania, zirconia, calcium carbonate, barium sulfate, a zeolite, interstitial clay, and combinations thereof.
24. A fuel cell comprising: (i) an oxygen-reducing cathode comprised of an electrically conductive support bound to particle composites comprising a palladium or palladium alloy nanoparticle coated with an atomically thin layer of platinum atoms; (ii) an anode; (iii) an electrically conductive contact connecting said oxygen-reducing cathode with said anode; and (iv) an ion-conducting electrolyte in mutual contact with said oxygen-reducing cathode and said anode.
25. The A fuel cell according to claim 24, wherein the electrically conductive support is carbon-based.
26. The fuel cell according to claim 25, wherein said electrically conductive support is carbon black, graphitized carbon, graphite, or activated carbon.
27. A method for producing electrical energy, the method comprising: (i) providing a fuel cell comprising: a) an oxygen-reducing cathode comprised of an electrically conductive support bound to nanoparticle composites comprising a palladium or palladium alloy core coated with an atomically thin layer of platinum atoms; b) an anode; c) an electrically conductive contact connecting said oxygen-reducing cathode with said anode; and d) an ion-conducting electrolyte in mutual contact with said oxygen-reducing cathode and said anode; (ii) contacting said oxygen-reducing cathode with oxygen; and (iii) contacting said anode with a fuel source.
28. The method of claim 27, wherein the fuel source is hydrogen gas.
29. The method of claim 28, wherein the hydrogen gas is generated from reformed methanol.
30. The method of claim 28, wherein the hydrogen gas is generated from reformed methane.
31. The method of claim 28, wherein the hydrogen gas is generated from reformed gasoline.
32. The method of claim 27, wherein the fuel source is an alcohol.
33. The method of claim 32, wherein the alcohol is methanol.
34. A method for reducing oxygen gas, the method comprising contacting a nanoparticle composite comprising a palladium or palladium alloy nanoparticle coated with an atomically thin layer of zerovalent platinum atoms with oxygen gas.
35. A particle composite comprising a homogeneous or heterogeneous metal alloy core comprising a combination of two or more metals selected from second row and third row transition metals; or said metal alloy core comprising one or more second row and/or third row transition metals in combination with one or more first row transition metals; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
36. The particle composite according to claim 35, wherein said atomically thin layer of platinum atoms is selected from the group consisting of an atomic submonolayer, monolayer, bilayer, trilayer, and combinations thereof, of platinum atoms.
37. The particle composite according to claim 36, wherein said atomically thin layer of platinum atoms is an atomic monolayer of platinum atoms.
38. The particle composite according to claim 35, wherein said metal alloy core is comprised of a combination of two or more metals selected from second row and third row transition metals.
39. The particle composite according to claim 38, wherein said metal alloy core comprises a combination of two or more metals selected from the group consisting of palladium, rhenium, gold, rhodium, iridium, ruthenium, and osmium.
40. The particle composite according to claim 39, wherein said metal alloy core is comprised of a homogeneous or heterogeneous alloy of rhenium-gold, rhenium-iridium, rhenium-rhodium, or rhenium-ruthenium.
41. The particle composite according to claim 38, wherein said metal alloy core is comprised of a homogeneous or heterogeneous alloy of rhenium-gold or rhenium-iridium.
42. The particle composite according to claim 35, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals in combination with one or more first row transition metals.
43. The particle composite according to claim 42, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium, in combination with one or more first row transition metals.
44. The particle composite according to claim 43, wherein said metal alloy core is comprised of zerovalent or charged gold atoms in combination with one or a combination of first row transition metals.
45. The particle composite according to claim 42, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals in combination with one or more first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron.
46. The particle composite according to claim 45, wherein said metal alloy core is comprised of one or a combination of second row and/or third row transition metal atoms in combination with zerovalent nickel.
47. The particle composite according to claim 42, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium, in combination with one or more first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron.
48. The particle composite according to claim 47, wherein said metal alloy core is comprised of zerovalent or charged gold atoms in combination with zerovalent nickel.
49. The particle composite according to claim 42, wherein said metal alloy core is at least partially homogeneous.
50. The particle composite according to claim 48, wherein said metal alloy core is at least partially homogeneous.
51. The particle composite according to claim 42, wherein said metal alloy core is at least partially heterogeneous.
52. The particle composite according to claim 48, wherein said metal alloy core is at least partially heterogeneous.
53. The particle composite according to claim 51, wherein said metal alloy core is comprised of an inner subcore comprising one or a combination of first row transition metals; said inner subcore at least partially encapsulated by an outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metal atoms.
54. The particle composite according to claim 53, wherein said outer shell is atomically thin.
55. The particle composite according to claim 54, wherein said outer shell is selected from the group consisting of an atomic submonolayer, monolayer, bilyaer, trilayer, and combinations thereof, of said one or combination of second row and/or third row transition metals.
56. The particle composite according to claim 53, wherein said metal alloy core is comprised of an inner subcore of one or a combination of first row transition metals selected from the group consisting of zerovalent iron, cobalt, and nickel; said inner subcore at least partially encapsulated by an outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metals selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium.
57. The particle composite according to claim 56, wherein said metal alloy core comprises an inner subcore of zerovalent nickel; said inner subcore at least partially encapsulated by an outer shell comprised of zerovalent or charged gold atoms.
58. The particle composite according to claim 35, further comprising metal-bonding ligands or surfactants on said atomically thin layer of platinum atoms.
59. The particle composite according to claim 35, wherein the particle composite has a size of approximately three nanometers to one hundred nanometers.
60. The particle composite according to claim 59, wherein the particle composite has a size of approximately three to ten nanometers.
61. The particle composite according to claim 60, wherein the particle composite has a size of approximately five nanometers.
62. The particle composite according to claim 35, wherein said metal alloy core is at least partially encapsulated by an atomic submonolayer of said platinum atoms.
63. The particle composite according to claim 62, wherein said atomic submonolayer of platinum atoms is in combination with a submonolayer of one or a combination of metal atoms other than platinum, thereby providing a platinum-metal alloy monolayer.
64. The particle composite according to claim 63, wherein said one or a combination of metal atoms other than platinum are one or a combination of transition metal atoms other than platinum.
65. The particle composite according to claim 64, wherein said one or a combination of transition metal atoms other than platinum are selected from the group consisting of iridium, ruthenium, osmium, rhenium, and gold.
66. The particle composite according to claim 65, wherein said platinum-metal alloy monolayer is a platinum-iridium alloy monolayer.
67. The particle composite according to claim 65, wherein said platinum-metal alloy monolayer is a platinum-ruthenium alloy monolayer.
68. The particle composite according to claim 65, wherein said platinum-metal alloy monolayer is a platinum-osmium alloy monolayer.
69. The particle composite according to claim 65, wherein said platinum-metal alloy monolayer is a platinum-rhenium alloy monolayer.
70. The particle composite according to claim 65, wherein said platinum-metal alloy monolayer is a platinum-gold alloy monolayer.
71. A particle composite comprising a metal alloy core comprising an inner subcore of one or a combination of first row transition metal atoms; said inner subcore at least partially encapsulated by an outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metal atoms; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
72. A particle composite comprising a metal alloy core comprising an inner subcore of one or a combination of first row transition metals selected from zerovalent iron, cobalt, and nickel; said inner subcore at least partially encapsulated by an atomically thin outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metal atoms selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
73. A particle composite comprising a metal alloy core comprising an inner subcore of one or a combination of first row transition metals selected from zerovalent iron, cobalt, and nickel; said inner subcore at least partially encapsulated by an atomically thin outer shell comprised of an oxide composition of one or a combination of second row and/or third row transition metals selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
74. A particle composite comprising a metal alloy core comprising an inner subcore of one or a combination of first row transition metals selected from zerovalent iron, cobalt, and nickel; said inner subcore at least partially encapsulated by an atomically thin outer shell comprised of zerovalent or charged gold atoms; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
75. A particle composite comprising a metal alloy core comprising an inner subcore of one or a combination of first row transition metals selected from zerovalent iron, cobalt, and nickel; said inner subcore at least partially encapsulated by an atomically thin outer shell comprised of zerovalent or charged rhenium atoms; said metal alloy core at least partially encapsulated.
76. A particle composite comprising a metal alloy core comprising an inner subcore of one or a combination of first row transition metals selected from zerovalent iron, cobalt, and nickel; said inner subcore at least partially encapsulated by an atomically thin outer shell of rhenium oxide; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
77. A particle composite comprising a metal core of rhenium, iridium, or rhodium, said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
78. A suspension or dispersion comprising particle composites suspended or dispersed in a liquid phase, said particle composites comprising a homogeneous or heterogeneous metal alloy core comprising a combination of two or more metals selected from second row and/or third row transition metals; or, said metal alloy core comprising one or more second row and/or third row transition metals in combination with one or more first row transition metals; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
79. The suspension or dispersion according to claim 78, wherein said particle composites comprise a metal alloy core comprising one or a combination of second row and/or third row transition metals in combination with one or a combination of first row transition metals, said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
80. The suspension or dispersion according to claim 79, wherein said one or combination of second row and/or third row transition metals are selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium.
81. The suspension or dispersion according to claim 78, wherein said liquid phase is aqueous-based.
82. A catalyst comprising particle composites bound to a support, said particle composites comprising a homogeneous or heterogeneous metal alloy core comprising a combination of two or more metals selected from second row and/or third row transition metals; or said metal alloy core comprising one or more second row and/or third row transition metals in combination with one or more first row transition metals; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
83. The catalyst according to claim 82, wherein said particle composite comprises a metal alloy core comprising one or a combination of second row and/or third row transition metal atoms in combination with one or a combination of first row transition metal atoms, said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent.
84. The catalyst according to claim 83, wherein said one or combination of second row and/or third row transition metals are selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium, and said one or combination of first row transition metals are selected from the group consisting of nickel, cobalt, and iron.
85. The catalyst according to claim 82, wherein said support is selected from the group consisting of carbon black, graphitized carbon, graphite, activated carbon, alumina, silica, silica-alumina, titania, zirconia, calcium carbonate, barium sulfate, a zeolite, interstitial clay, and combinations thereof.
86. A fuel cell comprising: (i) an oxygen-reducing cathode comprised of an electrically conductive support bound to particle composites comprising a homogeneous or heterogeneous metal alloy core comprising a combination of two or more metals selected from second row and third row transition metals; or said metal alloy core comprising one or more second row and/or third row transition metals in combination with one or more first row transition metals; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent; (ii) an anode; (iii) an electrically conductive contact connecting said oxygen-reducing cathode with said anode; and (iv) an ion-conducting electrolyte in mutual contact with said oxygen-reducing cathode and said anode.
87. The fuel cell according to claim 86, wherein said ion-conducting electrolyte is a proton-conducting electrolyte.
88. The fuel cell according to claim 87, wherein said proton-conducting electrolyte is a proton-conducting membrane.
89. The-fuel cell according to claim 86, wherein said metal alloy core comprises a combination of two or more metals selected from second row and third row transition metals.
90. The fuel cell according to claim 89, wherein said second row and third row transition metals are selected from the group consisting of palladium, rhenium, gold, rhodium, iridium, ruthenium, and osmium.
91. The fuel cell according to claim 90, wherein said metal alloy core comprises a homogeneous or heterogeneous alloy of rhenium-gold, rhenium-iridium, rhenium-rhodium, or rhenium-ruthenium.
92. The fuel cell according to claim 91, wherein said metal alloy core comprises a homogeneous or heterogeneous alloy of rhenium-gold or rhenium-iridium.
93. The fuel cell according to claim 86, wherein said metal alloy core comprises one or more second and/or third row transition metals in combination with one or more first row transition metals.
94. The fuel cell according to claim 93, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium, in combination with one or more first row transition metals.
95. The fuel cell according to claim 94, wherein said metal alloy core is comprised of zerovalent or charged gold atoms in combination with one or a combination of first row transition metal atoms.
96. The fuel cell according to claim 93, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals in combination with one or more first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron.
97. The fuel cell according to claim 96, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals in combination with zerovalent nickel.
98. The fuel cell according to claim 93, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium, in combination with one or more first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron.
99. The fuel cell according to claim 98, wherein said metal alloy core is comprised of zerovalent or charged gold atoms in combination with zerovalent nickel atoms.
100. The fuel cell according to claim 93, wherein said metal alloy core is at least partially heterogeneous.
101. The fuel cell according to claim 100, wherein said metal alloy core is comprised of an inner subcore comprising one or a combination of first row transition metals, said inner subcore at least partially encapsulated by an outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metal atoms.
102. The fuel cell according to claim 101, wherein said outer shell is atomically thin.
103. The fuel cell according to claim 102, wherein said outer shell is selected from the group consisting of an atomic submonolayer, monolayer, bilayer, trilayer, and combinations thereof, of said one or combination of zerovalent or charged second row and/or third row transition metal atoms.
104. The fuel cell according to claim 101, wherein said metal alloy core is comprised of an inner subcore comprised of one or a combination of first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron; said inner subcore at least partially encapsulated by an outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metal atoms selected from the group consisting of gold, rhodium, iridium, ruthenium, osmium, and rhenium.
105. The fuel cell according to claim 104, wherein said metal alloy core is comprised of an inner subcore comprised of one or a combination of first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron; said inner subcore at least partially encapsulated by an outer shell comprised of zerovalent or charged gold atoms.
106. The fuel cell according to claim 104, wherein said metal alloy core is comprised of an inner subcore comprised of one or a combination of first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron; said inner subcore at least partially encapsulated by an outer shell comprised of zerovalent or charged rhenium atoms.
107. The fuel cell according to claim 104, wherein said metal alloy core is comprised of an inner subcore comprised of one or a combination of first row transition metals selected from the group consisting of zerovalent nickel, cobalt, and iron; said inner subcore at least partially encapsulated by an outer shell of an oxide of rhenium.
108. The fuel cell according to claim 86, wherein said electrically conductive support is carbon-based.
109. The fuel cell according to claim 108, wherein said electrically conductive support is selected from the group consisting of carbon black, graphitized carbon, graphite, and activated carbon.
110. A fuel cell comprising: (i) an oxygen-reducing cathode; (ii) an anode comprised of an electrically conductive support bound to particle composites comprising a homogeneous or heterogeneous metal alloy core comprising a combination of two or more metals selected from second row and third row transition metals; or said metal alloy core comprising one or more second row and/or third row transition metals in combination with one or more first row transition metals; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent; (iii) an electrically conductive contact connecting said oxygen-reducing cathode with said anode; and (iv) an ion-conducting electrolyte in mutual contact with said oxygen-reducing cathode and said anode.
111. The fuel cell according to claim 110, wherein said metal alloy core comprises a combination of two or more metals selected from second row and/or third row transition metals, said second row and/or third row transition metals selected from the group consisting of palladium, rhenium, gold, rhodium, iridium, ruthenium, and osmium.
112. The fuel cell according to claim 110, wherein said metal alloy core is comprised of one or a combination of second row and/or third row transition metals in combination with one or a combination of first row transition metals.
113. The fuel cell according to claim 112, wherein said metal alloy core is comprised of an inner subcore comprising one or a combination of first row transition metals, said inner subcore at least partially encapsulated by an outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metal atoms.
114. A fuel cell comprising: (i) an oxygen-reducing cathode comprised of an electrically conductive support bound to particle composites comprising a metal core comprised of rhenium, iridium, or rhodium, said metal core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent; (ii) an anode; (iii) an electrically conductive contact connecting said oxygen-reducing cathode with said anode; and (iv) an ion-conducting electrolyte in mutual contact with said oxygen-reducing cathode and said anode.
115. A method for producing electrical energy, the method comprising: (i) providing a fuel cell comprising: a) an oxygen-reducing cathode comprised of an electrically conductive support bound to particle composites comprising a homogeneous or heterogeneous metal alloy core comprising a combination of two or more metals selected from second row and third row transition metals; or said metal alloy core comprising one or more second row and/or third row transition metals in combination with one or more first row transition metals; said metal alloy core at least partially encapsulated by an atomically thin layer of platinum atoms, wherein at least a portion of said platinum atoms are zerovalent; b) an anode; c) an electrically conductive contact connecting said oxygen-reducing cathode with said anode; and d) an ion-conducting electrolyte in mutual contact with said oxygen-reducing cathode and said anode; (ii) contacting said oxygen-reducing cathode with oxygen; and (iii) contacting said anode with a fuel source.
116. The method according to claim 115, wherein said metal alloy core comprises a combination of two or more metals selected from second row and/or third row transition metals, said second row and/or third row transition metals selected from the group consisting of palladium, rhenium, gold, rhodium, iridium, ruthenium, and osmium.
117. The method according to claim 1, wherein said metal alloy core is comprised of one or more second row and/or third row transition metals in combination with one or more first row transition metals.
118. The method according to claim 117, wherein said metal alloy core is comprised of an inner subcore comprising one or a combination of first row transition metals, said inner subcore at least partially encapsulated by an outer shell comprised of one or a combination of zerovalent or charged second row and/or third row transition metal atoms.
119. The method of claim 115, wherein the fuel source is hydrogen gas.
120. The method of claim 119, wherein the hydrogen gas is generated from reformed methanol.
121. The method of claim 119, wherein the hydrogen gas is generated from reformed methane.
122. The method of claim 119, wherein the hydrogen gas is generated from reformed gasoline.
123. The method of claim 115, wherein the fuel source is an unreformed alcohol.
124. The method of claim 123, wherein the alcohol is methanol.
This application is a continuation-in-part of, and asserts priority to, U.S. application Ser. No. 11/019,759 filed Dec. 22, 2004. The specification of U.S. application Ser. No. 11/019,759 is hereby incorporated by reference in its entirety.
This invention was made with Government support under contract number DE-AC02-98CH10886, awarded by the U.S. Department of Energy. The Government has certain rights in the invention.
The present invention relates to platinum-coated particles useful as fuel cell electrocatalysts. The invention particularly relates to such particles having a palladium, palladium alloy, gold alloy, or rhenium alloy core encapsulated by a thin coating of platinum.
BACKGROUND OF THE INVENTION
A “fuel cell” is a device which converts chemical energy into electrical energy. In a typical fuel cell, a gaseous fuel, such as hydrogen, is fed to an anode (the negative electrode), while an oxidant, such as oxygen, is fed to a cathode (the positive electrode). Oxidation of the fuel at the anode causes a release of electrons from the fuel into an electrically conducting external circuit which connects the anode and cathode. In turn, the oxidant is reduced at the cathode using the electrons provided by the oxidized fuel.
The electrical circuit is completed by the flow of ions through an electrolyte that allows chemical interaction between the electrodes. The electrolyte is typically in the form of a proton-conducting polymer membrane. The proton-conducting membrane separates the anode and cathode compartments while allowing the flow of protons between them. A well-known example of such a proton-conducting membrane is NAFION®.
A fuel cell, although having components and characteristics similar to those of a typical battery, differs in several respects. A battery is an energy storage device whose available energy is determined by the amount of chemical reactant stored within the battery itself. The battery will cease to produce electrical energy when the stored chemical reactants are consumed. In contrast, the fuel cell is an energy conversion device that theoretically has the capability of producing electrical energy for as long as the fuel and oxidant are supplied to the electrodes.
In a hydrogen/oxygen fuel cell, hydrogen is supplied to the anode and oxygen is supplied to the cathode. Hydrogen molecules are oxidized to form protons while releasing electrons into the external circuit. Oxygen molecules are reduced at the cathode to form reduced oxygen species. Protons travel across the proton-conducting membrane to the cathode compartment to react with reduced oxygen species, thereby forming water. The reactions in a typical hydrogen/oxygen fuel cell are as follows:
Anode: 2H 2 →4H + +4e − (1)
Cathode: O 2 +4H++4e − →2H 2 O (2)
Net Reaction: 2H 2 +O 2 →2H 2 O (3)
In many fuel cell systems, a hydrogen fuel is produced by converting a hydrocarbon-based fuel such as methane, or an oxygenated hydrocarbon fuel such as methanol, to hydrogen in a process known as “reforming”. The reforming process typically involves the reaction of such fuels with water along with the application of heat. By this reaction, hydrogen is produced. The byproducts of carbon dioxide and carbon monoxide typically accompany the production of hydrogen in the reformation process.
Other fuel cells, known as “direct” or “non-reformed” fuel cells, directly oxidize fuels high in hydrogen content. For example, it has been known for some time that lower primary alcohols, particularly methanol, can be oxidized directly. Due to the advantage of bypassing the reformation step, a substantial effort has gone into the development of so-called “direct methanol oxidation” fuel cells.
In order for the oxidation and reduction reactions in a fuel cell to occur at useful rates and at desired potentials, electrocatalysts are required. Electrocatalysts are catalysts that promote the rates of electrochemical reactions, and thus, allow fuel cells to operate at lower potentials. Accordingly, in the absence of an electrocatalyst, a typical electrode reaction would occur, if at all, only at very high potentials. Due to the high catalytic nature of platinum, platinum and platinum alloy materials are preferred as electrocatalysts in the anodes and cathodes of fuel cells.
However, a significant obstacle in commercializing fuel cells is the limitation of current platinum electrocatalysts. For example, one major problem is found in the slow kinetics of oxygen reduction in current platinum oxygen-reducing cathodes. In addition, a large loss in potential of 0.3-0.4 volts is typically observed during operation of fuel cells containing these platinum electrocatalysts. This loss in potential is the source of a major decline in the fuel cell's efficiency.
Another problem in existing electrocatalyst technology is the high platinum loading in fuel cell cathodes. Since platinum is a high-cost precious metal, high platinum loading translates to high costs of manufacture.
Accordingly, there have been efforts to reduce the amount of platinum in electrocatalysts. For example, platinum nanoparticles have been studied as electrocatalysts. See, for example, U.S. Pat. No. 6,007,934 to Auer et al.; and U.S. Pat. No. 4,031,292 to Hervert.
Platinum-alloy compositions have also been studied. In particular, platinum-palladium alloy nanoparticles have been studied. See, for example, U.S. Pat. No. 6,232,264; Solla-Gullon, J., et al, “Electrochemical And Electrocatalytic Behaviour Of Platinum-Palladium Nanoparticle Alloys”, Electrochem. Commun., 4, 9: 716 (2002); and Holmberg, K., “Surfactant-Templated Nanomaterials Synthesis”, J. Colloid Interface Sci., 274: 355 (2004).
Other platinum-alloy compositions have been studied. For example, U.S. Pat. No. 5,759,944 to Buchanan et al. discloses platinum-nickel and platinum-nickel-gold electrocatalyst compositions.
U.S. Pat. No. 6,670,301 B2 to Adzic et al. relates to an atomic monolayer of platinum on ruthenium nanoparticles. The platinum-coated ruthenium nanoparticles are disclosed as carbon monoxide-tolerant anode electrocatalysts useful in fuel cells. See also Brankovic, S. R., et al., “Pt Submonolayers On Ru Nanoparticles—A Novel Low Pt Loading, High CO Tolerance. Fuel Cell Electrocatalyst,” Electrochem. Solid State Lett., 4, p. A217 (2001); and Brankovic, S. R., et al, “Spontaneous Deposition Of Pt On The Ru(0001) Surface”, J. Electroanal. Chem., 503: 99 (2001), which also disclose platinum monolayers on ruthenium nanoparticles.
None of the art considered above disclose platinum-coated particles, particularly nanoparticles, useful as oxygen-reducing electrocatalysts and having low platinum loading. Yet, there is a need for electrocatalysts having these advantages. The present invention relates to such electrocatalysts.
SUMMARY OF THE INVENTION
In one aspect, the present invention relates to platinum- and platinum alloy-coated palladium or palladium alloy particles. The platinum and platinum alloy coatings are atomically thin layers, i.e., atomic submonolayers, monolayers, bilayers, trilayers, or combinations thereof.
In one embodiment, an atomic submonolayer of platinum contains only platinum atoms in the absence of other co-deposited metal atoms.
In another embodiment, an atomic submonolayer of platinum atoms includes one or more co-deposited atomic submonolayers of another metal to form a platinum-metal alloy monolayer. The co-deposited metal(s) in the platinum-alloy monolayer can be, for example, a main group, transition, lanthanide, or actinide metal. The co-deposited metal is preferably a transition metal.
More preferably, the co-deposited metal is iridium (Ir), ruthenium (Ru), osmium (Os), rhenium (Re), or any combination thereof. Even more preferably, the platinum-metal alloy monolayer is according to the molar composition M 0.2 Pt 0.8 , where M is Ir, Ru, Os, or Re. Most preferably, the platinum-metal alloy monolayer is according to the molar composition Re 0.2 Pt 0.8 or Os 0.2 Pt 0.8 .
The platinum-coated palladium or palladium alloy nanoparticles preferably have a minimum size of about 3 nanometers and a maximum size of about 10 nanometers. The maximum size of the nanoparticles is preferably no more than about 12 nanometers. The platinum-coated palladium or palladium alloy nanoparticles most preferably have a size of about 5 nanometers.
When applied as fuel cell electrocatalysts, the particle composites are preferably platinum monolayer- or submonolayer-coated palladium or palladium alloy particles. The particles are even more preferably nanoparticles.
One embodiment relates to platinum-coated palladium particles. The platinum-coated palladium particles contain a core composed of zerovalent palladium.
In one embodiment, the palladium core is coated with a shell of zerovalent platinum atoms. In another embodiment, the palladium core is coated with a shell of platinum atoms wherein at least some portion of the platinum atoms are in a zerovalent oxidation state and the remainder of the platinum atoms are charged.
Another embodiment relates to platinum-coated noble metal cores wherein the noble metal is other than palladium. Some examples of such noble metal cores include those composed of rhenium, iridium, or rhodium. These noble metal cores are at least partially encapsulated by an atomically thin layer of platinum atoms. At least a portion of the platinum atoms are in a zerovalent oxidation state.
Another embodiment relates to platinum-coated metal alloy particles. These particles contain a core composed of a metal alloy which is at least partially encapsulated by an atomically thin layer of platinum atoms, at least a portion of which are in a zerovalent oxidation state.
The metal alloy core is preferably composed of a combination of two or more metals selected from second row and third row transition metals. For example, the metal alloy core can be a combination of two or more second row transition metals, a combination of two or more third row transition metals, or a combination of one or more second row transition metals and one or more third row transition metals.
The second row and third row transition metals are more preferably metals having noble character. Some examples of second row and third row transition metals having noble character include ruthenium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.
For example, the metal alloy core can be a homogeneous or heterogeneous alloy of palladium-ruthenium, palladium-rhenium, palladium-iridium, palladium-rhodium, palladium-gold, rhodium-gold, iridium-gold, ruthenium-gold, osmium-gold, rhenium-gold, iridium-rhodium, ruthenium-rhodium, osmium-rhodium, rhenium-rhodium, ruthenium-iridium, osmium-iridium, rhenium-iridium, osmium-ruthenium, rhenium-ruthenium, and rhenium-osmium. Particularly preferred are metal alloy cores having rhenium-gold and rhenium-iridium compositions.
In another embodiment, the metal alloy core is composed of a combination of one or more second row and/or third row transition metals in combination with one or more first row transition metals. Particularly preferred are metal alloy cores composed of one or more noble metals in combination with one or more first row transition metals.
In one embodiment, the metal alloy core is a homogeneous or heterogeneous alloy of one or a combination of zerovalent or charged 4d (second row) and/or 5d (third row) transition metals in combination with one or a combination of 3d (first row) transition metals. Preferably, the one or combination of 4d and/or 5d transition metals are selected from zerovalent or charged atoms of gold, rhodium, iridium, ruthenium, osmium, and rhenium. More preferably, the foregoing 4d and/or 5d transition metals are combined with one or a combination of zerovalent 3d transition metals selected from nickel, cobalt, and iron.
For example, particularly preferred is the class of platinum-coated palladium alloy particles. The platinum-coated palladium alloy particles contain a core composed of zerovalent palladium alloy. The palladium alloy core is coated with a shell of zerovalent or partially charged platinum or platinum-alloy.
Preferably, the alloying component in the palladium alloy is a metal or combination of metals other than platinum. More preferably, the alloying metal is one or more transition metals. Even more preferably, the alloying metal is one or more 3d transition metals, i.e., the row of transition metals starting with scandium (Sc). Even more preferably, the alloying metals are selected from nickel (Ni), cobalt (Co), iron (Fe), or any combination thereof. Gold (Au), or its combination with other metals, particularly, Ni, Co, and Fe, are other preferred alloying metals.
Another particularly preferred class of platinum-coated metal alloy particles is the class of platinum-coated gold alloy cores. Preferably, the gold alloy core is composed of gold in combination with one or a combination of first row transition metals. More preferably, the one or more first row transition metals are selected from nickel, cobalt, and iron. Even more preferably, the gold alloy core is an alloy of gold and nickel.
In one embodiment, the metal alloy core is homogeneous. A homogeneous metal alloy core contains a metal and one or more alloying components distributed uniformly-throughout the core.
In another embodiment, the metal alloy core is heterogeneous. In a preferred embodiment, a heterogeneous core is composed of an inner subcore and an outer shell. The inner subcore is preferably composed of one or a combination of metals of less-noble or non-noble character as compared to the one or combination of metals of the outer shell.
For example, a palladium alloy core can be heterogeneous. An example of a heterogeneous palladium-metal alloy core is one having a non-palladium inner subcore encapsulated by an outer shell of palladium. The outer shell of palladium is bonded to the atomically thin coating of platinum.
The inner subcore is preferably composed of one or a combination of first row transition metals. Preferably, such an inner subcore is at least partially encapsulated by an outer shell composed of one or a combination of metals selected from second row and/or third row transition metals. The outer shell is more preferably composed of one or a combination of metals having noble character.
The outer shell of second row and/or third row transition metals is more preferably atomically thin. For example, the outer shell is preferably an atomic submonolayer, monolayer, bilayer, trilayer, or a combination thereof, of the second row and/or third row transition metals.
In a particularly preferred embodiment, a subcore composed of one or a combination of zerovalent first row transition metals selected from nickel, cobalt, and iron, is encapsulated by an outer shell composed of one or a combination of zerovalent or charged second row and/or third row transition metal atoms selected from gold, palladium, rhodium, iridium, ruthenium, osmium, and rhenium.
Another particularly preferred heterogeneous core includes a subcore of zerovalent nickel, cobalt, iron, or a combination thereof, at least partially encapsulated by an outer shell of zerovalent or charged gold atoms. Even more preferably, the outer shell of gold is an atomically thin layer of gold. Even more preferably, the atomically thin layer of gold is an atomic monolayer of gold. The atomically thin layer of platinum bonded to the atomically thin layer of gold is preferably an atomic monolayer of platinum.
Another particularly preferred heterogeneous core contains a subcore of one or a combination of zerovalent first row transition metals at least partially encapsulated by an outer shell of one or a combination of second row and/or third row transition metal atoms selected from rhodium, iridium, ruthenium, osmium, and rhenium. More preferably, the outer shell is an atomically thin layer of one or more of the foregoing metals.
In one embodiment, the outer shell is composed of zerovalent rhodium, iridium, ruthenium, osmium, or rhenium atoms. In another embodiment, some portion of the outer shell is composed of charged rhodium, iridium, ruthenium, osmium, or rhenium atoms. In a particular embodiment, the outer shell is composed of an oxide of rhodium, iridium, ruthenium, osmium, or rhenium.
When appropriate, the particle and nanoparticle composites as thus far described can have metal-bonding ligands or surfactants bound to, or associated with, the surface layer of zerovalent or partially charged platinum.
The particle and nanoparticle composites can also be in the form of a suspension or dispersion in a liquid phase. The liquid phase can be any suitable liquid phase such as an organic solvent or an alcohol. Preferably, the liquid phase is aqueous-based. Some examples of suitable aqueous-based liquid phases include water and water-alcohol mixtures.
In another embodiment, the invention relates to a catalyst. The catalyst includes the platinum-coated particles as thus far described.
In one embodiment, the platinum-coated particles in the catalyst are bound to a support. The support can be any suitable support. For example, the support can be carbon, alumina, silica, silica-alumina, titania, zirconia, calcium carbonate, barium sulphate, a zeolite, interstitial clay, and the like. In another embodiment, the platinum-coated particles in the catalyst are not bound to a support.
In another embodiment, the particle composites of the invention are applied as electrocatalysts, and particularly, oxygen reduction electrocatalysts. The oxygen reduction electrocatalysts are preferably bound to an electrically conductive support. Some preferred. electrically conductive supports include carbon black, graphitized carbon, graphite, or activated carbon.
In another embodiment, the invention relates to a method for reducing oxygen gas. In one embodiment, the method uses the particle composites described above to reduce oxygen gas. The particle composites can be in the form of a solid, or alternatively, dispersed or suspended in a liquid phase when contacting oxygen gas. In another embodiment, the particle composites are bound to a support when reducing oxygen gas.
In another embodiment, the invention relates to a fuel cell. In the fuel cell, the oxygen-reducing cathode contains the platinum-coated particle composites bound to an electrically conductive support. The fuel cell additionally contains the other elements typical of a fuel cell, e.g., an anode, an ion-conducting electrolyte, and an electrical contact between the anode and cathode. The ion-conducting electrolyte is more preferably a proton-conducting electrolyte, and even more preferably a solid proton-conducting electrolyte, such as a proton-conducting membrane.
In a method for generating electrical energy, the oxygen-reducing cathode of the fuel cell is contacted with an oxidant, such as oxygen, while the anode of the fuel cell is contacted with a fuel source.
Some contemplated fuel sources include, for example, hydrogen gas and alcohols. The fuels can be unreformed or reformed.
Some examples of suitable alcohols include methanol and ethanol. Examples of other fuels include methane, gasoline, formic acid, dimethyl ether, and ethylene glycol.
As a result of the present invention, improved oxygen-reducing catalytic activities and further reductions in platinum loading can be made possible.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1. Comparison of polarization curves for oxygen reduction on palladium nanoparticles, 10 nmol loading (left curve); commercial platinum nanoparticles, 10 nmol loading (second to left curve); and platinum-coated palladium nanoparticles of the present invention, 10 and 20 nmol Pd loadings, (two right curves).
FIG. 2. Comparison of Pt mass-specific activities of platinum nanoparticles (10 nmol Pt loading) and platinum-coated palladium nanoparticles of the present invention (1.3 and 2.4 nmol Pt loading, left and right sets of bars, respectively) on palladium nanoparticles (10 and 20 nmol Pd loadings).
FIG. 3. Comparison of polarization curves for oxygen reduction on commercial platinum nanoparticles, 10 nmol loading (left curve); platinum-coated palladium nanoparticles of the present invention, 20 nmol Pd loading (middle curve), and Ir 0.2 Pt 0.8 -coated palladium nanoparticles of the present invention (right curve).
FIG. 4. Comparison of the activities of Ir x Pt 1−x -coated and Ru x Pt 1−x -coated palladium nanoparticles of the present invention as a function of molar ratio x at 0.8V.
FIG. 5. X-ray spectroscopy absorption peak of Pt—OH formation as a function of potential for Pt monolayer on palladium nanoparticles and Pt monolayer on carbon.
FIG. 6. Comparison of polarization curves for oxygen reduction on commercial platinum nanoparticles of 10 nmol Pt loading (Pt 10 /C, left curve); and platinum-coated gold-nickel alloy nanoparticles of the present invention (Pt ML /AuNi 10 /C, right curve, where ML=monolayer).
FIG. 7. Comparison of Pt and (Pt+Au) mass-specific activities of platinum nanoparticles of 10 nmol Pt loading (Pt 10 /C) and platinum-coated gold-nickel alloy nanoparticles of the present invention (Pt ML /AuNi 10 /C) expressed as the current at 0.80 V and 0.85 V.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates, generally, to particle composites having a metal or metal alloy core coated with, or at least partially encapsulated by, an atomically thin surface layer of zerovalent or charged platinum atoms.
Preferably, at least a portion of the platinum atoms in the atomically thin layer of platinum are in a zerovalent oxidation state. The atomically thin layer of platinum atoms can be composed of platinum atoms which are all zerovalent, or alternatively, wherein a portion of the platinum atoms are charged and some portion zerovalent.
The atomically thin surface layer of platinum can have a thickness of up to a few atom layers of zerovalent or partially charged platinum. Preferably, the atomically thin surface layer is a layer of zerovalent platinum atoms of sub-monoatomic, monoatomic, diatomic, or triatomic thickness, or any combination thereof.
A layer of monoatomic thickness of platinum atoms, i.e., an atomic monolayer, is a single layer of close-packed platinum atoms on the palladium or palladium alloy substrate particle surface. An atomic monolayer has a surface packing parameter of 1.
A layer of sub-monoatomic coverage, i.e., an atomic submonolayer, is a layer of platinum atoms which is less dense than an atomic monolayer (i.e., not close-packed). Accordingly, an atomic submonolayer has a surface packing parameter of less than 1. For example, a surface packing parameter of 0.5 indicates half the density of platinum atoms as compared to a platinum atomic monolayer.
A layer of diatomic thickness refers to a bilayer (two-atom thick) of zerovalent or charged platinum atoms. A layer of triatomic thickness refers to a trilayer (three-atom thick) of zerovalent or charged platinum atoms.
In one embodiment, an atomic submonolayer of platinum contains only platinum atoms in the absence of other co-deposited metal atoms.
In another embodiment, an atomic submonolayer of platinum atoms includes one or more co-deposited atomic submonolayers of another metal to form a platinum alloy monolayer. The co-deposited metal(s) in the platinum alloy monolayer can be selected from, for example, the main group, transition, lanthanide, and actinide classes of metals.
The co-deposited metal(s) in such an atomically thin layer of platinum atoms provide such advantages as, for example, further reduction in platinum loading as compared to a purge platinum layer, reduction in catalytic poisoning, and/or enhancement of catalytic activity. For example, some metals, particularly some of the transition metals, have the ability to adsorb hydroxyl groups (OH). Hydroxyl groups are known to inhibit the oxygen-reducing catalytic activity of platinum. Therefore, particularly when applied as fuel cell catalysts, the co-depositing metal is more preferably a metal known to adsorb OH.
Preferably, the hydroxyl-adsorbing metal is a second row (4d) or third row (5d) transition metal which forms an oxide composition at suitable oxidizing potentials. Suitable oxidizing potentials are typically encountered during operation of a fuel cell at the cathode. Some examples of suitable hydroxyl-absorbing transition metals include iridium (Ir), ruthenium (Ru), osmium (Os), rhenium (Re), and combinations thereof. Oxide compositions of these metals help to suppress the adsorption of hydroxyl groups onto platinum.
The molar composition of such a platinum alloy monolayer is not particularly limited. For example, such a platinum alloy monolayer can be a binary alloy according to the molar composition formula M x Pt 1−x (1), wherein M is any of the metals described above.
In formula (1), the value of x is not particularly limited. Preferably, x has a minimum value of about 0.01, more preferably 0.05, and even more preferably 0.1. Preferably, x has a maximum value of about 0.99, more preferably a value of about 0.9, more preferably a value of about 0.6, and even more preferably, a maximum value of about 0.5. In a preferred embodiment, x has a value of about 0.2.
Some more specific platinum binary alloy monolayers of formula (1) are represented by the molar composition formulas Ir x Pt 1−x , Ru x Pt 1−x , Os x Pt 1−x , or Re x Pt 1−x . Some specific examples of platinum binary alloy monolayers include Ir 0.01 Pt 0.99 , Ir 0.1 Pt 0.9 , Ir 0.2 Pt 0.8 , Ir 0.3 Pt 0.7 , Ir 0.5 Pt 0.5 , Ir 0.7 Pt 0.3 , Ir 0.8 Pt 0.2 , Ir 0.9 Pt 0.1 , Ir 0.95 Pt 0.05 , Ru 0.01 Pt 0.99 , Ru 0.1 Pt 0.9 , Ru 0.2 Pt 0.8 , Ru 0.3 Pt 0.7 , Ru 0.5 Pt 0.5 , Ru 0.7 Pt 0.3 , Ru 0.8 Pt 0.2 , Ru 0.9 Pt 0.1 , Ru 0.95 Pt 0.05 , Os 0.2 Pt 0.8 , Os 0.5 Pt 0.5 , Os 0.7 Pt 0.3 , Os 0.8 Pt 0.2 , Os 0.9 Pt 0.1 , Re 0.2 Pt 0.8 , Re 0.5 Pt 0.5 , Re 0.7 Pt 0.3 , Re 0.8 Pt 0.2 , and Re 0.9 Pt 0.1 .
The platinum alloy monolayer can additionally be a ternary alloy. For example, the platinum alloy monolayer can be a ternary alloy according to the molar composition formula M x N y Pt 1−x−y (2). In formula (2), M and N are independently any of the suitable metals described above. The values of x and y are not particularly limited. By the rules of chemistry, the sum of x and y in formula (2) must be less than 1. For example, x and y can independently have a value of about 0.01 to a value of about 0.99, as long as the sum of x and y is less than 1.0. More preferably, the sum of x and y has a minimum value of about 0.1 and a maximum value of about 0.9.
Some more specific platinum ternary alloy monolayers of formula (2) are represented by the molar composition formulas Ir x Ru y Pt 1−x−y , Ir x Os y Pt 1−x−y , Ir x Re y Pt 1−x−y , Os x Ru y Pt 1−x−y , Re x Ru y Pt 1−x−y , and Re x Os y Pt 1−x−y . Some specific examples of ternary platinum-metal alloy monolayers include Ir 0.0 Ru 0.1 Pt 0.98 , Ir 0.1 Ru 0.1 Pt 0.8 , Ir 0.2 Ru 0.1 Pt 0.7 , Ir 0.1 Ru 0.2 Pt 0.7 , Ir 0.3 Ru 0.1 Pt 0.6 , Ir 0.5 Ru 0.1 Pt 0.4 , Ir 0.01 Os 0.01 Pt 0.98 , Ir 0.1 Os 0.1 Pt 0.8 , Ir 0.2 Os 0.1 Pt 0.7 , Ir 0.1 Os 0.2 Pt 0.7 , Ir 0.01 ,Re 0.01 Pt 0.98 , Ir 0.1 Re 0.1 Pt 0.8 , Ir 0.2 Re 0.1 Pt 0.7 , and Ir 0.1 Re 0.2 Pt 0.7 .
The platinum alloy monolayer can additionally be a quaternary alloy. For example, the platinum alloy monolayer can be a quaternary alloy according to the molar composition formula M x N y T z Pt 1−x−y−z (3). In formula (3), M, N, and T are independently any of the suitable metals described above. The values of x, y, and z are not particularly limited. By the rules of chemistry, the sum of x, y, and z in formula (3) must be less than 1. For example, x, y, and z can independently have a value of about 0.01 to a value of about 0.99 as long as the sum of x, y, and z is less than 1.0. More preferably, the sum of x, y, and z has a minimum value of about 0.1 and a maximum value of about 0.9.
Some more specific platinum quaternary alloy monolayers of formula (3) are represented by the formulas Ir x Ru y Re z Pt 1−x−y−z or Ir x Ru y Os z Pt 1−x−y−z . Some specific examples of quaternary platinum alloy monolayers include Ir 0.01 Ru 0.01 Re 0.1 Pt 0.97 , Ir 0.1 Ru 0.1 Re 0.1 Pt 0.7 , Ir 0.2 Ru 0.1 Os 0.1 Pt 0.6 , and Ir 0.1 Ru 0.2 Os 0.1 Pt 0.6 .
The metals alloying with platinum tend to selectively form oxides at suitable oxidation potentials. Accordingly, all of the examples given above for platinum alloy monolayers include the corresponding oxidized compositions, i.e., wherein platinum is combined (e.g., mixed or interlaced) with the oxide of the alloying metal. The oxide of the alloying metal can be designated as, for example, IrO v RuO v , OsO v , or ReO v , wherein the subscript v is a suitable generic or specific number of stoichiometric or non-stoichiometric proportion.
In a preferred embodiment, the atomically thin layer of platinum atoms covers or encapsulates the entire surface of the zerovalent metal or metal alloy core. In another embodiment, the atomically thin layer of platinum atoms covers a portion of, i.e., partially encapsulates, the zerovalent metal or metal alloy core. For example, the atomically thin layer of platinum surface atoms can be characterized as interconnected platinum islands with some regions of monoatomic, diatomic, or triatomic depth.
In one embodiment, the invention relates to platinum-coated palladium particles, i.e., particle composites having a zerovalent palladium core coated with, or at least partially encapsulated by, an atomically thin surface layer of platinum atoms. The platinum-coated palladium particles contain a core composed of palladium atoms in the zerovalent oxidation state.
Another embodiment relates to platinum-coated noble metal cores wherein the noble metal is other than palladium. Some examples of such noble metal cores include those composed of rhenium, iridium, rhodium, silver, and osmium. These noble metal cores are at least partially encapsulated by an atomically thin shell of zerovalent or charged platinum atoms.
Yet another embodiment relates to platinum-coated particle composites having a metal alloy core. The alloy in the metal alloy core can be homogeneous or heterogeneous, or a combination thereof. The metal alloy core can also be a binary, ternary, quaternary, or higher alloy.
The metal alloy core is preferably composed of a combination of two or more metals selected from second row (4d) and third row (5d) transition metals. For example, the metal alloy core can be a combination of two or more second row transition metals, or a combination of two or more third row transition metals, or a combination of one or more second row transition metals and one or more third row transition metals.
The second row and third row transition metals in the metal alloy core are more preferably metals having noble character. Some examples of second row and third row transition metals having noble character include ruthenium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.
particular relevance are particles having a palladium alloy core, i.e., the class of platinum-coated palladium alloy particles. The palladium alloy core is composed of zerovalent palladium atoms and an alloying component.
The alloying component in the palladium alloy core can be any chemical or chemicals capable of combining with palladium that do not include platinum or palladium. For example, the alloying component can be carbon, silicon, silicon oxide, a metal, a polymer or polymer end-product, a dendrimer, a natural-based product such as cellulose, and so on.
Preferably, the alloying component in the palladium alloy core is a metal or combination of metals not including palladium. For example, the metal in the palladium alloy can be an alkali, alkaline earth, main group, transition, lanthanide, or actinide metal.
More preferably, the alloying metal or metals in the palladium alloy core are transition metals. Even more preferably, the alloying component is one or more 3d transition metals, particularly nickel (Ni), cobalt (Co), and/or iron (Fe). Gold (Au), or its combination with other metals, particularly, Ni, Co, and Fe, are other preferred alloying components.
The palladium alloy core in the platinum-coated palladium alloy particles can be in a homogeneous form. A homogeneous palladium alloy composition is a form in which the palladium and the alloying component(s) are distributed uniformly on a molecular level throughout the particle. Some examples of homogeneous palladium alloy compositions include those with molar compositions 50:50 Pd—Ni, 80:20 Pd—Ni, 40:60 Pd—Ni, 60:40 Pd—Co, 30:70 Pd—Co, 70:30 Pd—Fe, 60:20:20 Pd—Ni—Co, 40:40:20 Pd—Ni—Fe, 90:5:5 Pd—Fe—Co, 60:20:10:10 Pd—Ni—Co—Fe, 50:50 Pd—Au, 80:20 Pd—Au, 20:80 Pd—Au, 10:90 Pd—Au, and 1:99 Pd—Au compositions.
Alternatively, the palladium alloy core is in a heterogeneous form. In a heterogeneous form, the palladium and the alloying component(s) are distributed with varying composition, i.e., non-uniformly, in the palladium alloy core. In such cases, there is a palladium component on the surface of the palladium alloy core.
For example, a heterogeneous palladium alloy core can have individual palladium grains intermingled with individual cobalt or carbon grains throughout the core; or alternatively, for example, a carbon, cobalt, nickel, iron, copper, ruthenium, gold, or silver sub-core surrounded by a palladium shell. Some other examples of heterogeneous palladium alloy compositions include a palladium shell on a sub-core of silicon, silicon oxide, silicon nitride, titanium oxide, aluminum oxide, iron oxide, metal salt, latex, carbon, and so on.
In addition, a palladium alloy core can have a combination of a homogeneous component and a heterogeneous component. An example of such a palladium alloy core is one that contains a homogeneous subcore of palladium alloy coated with a shell of palladium metal. Another example of such a palladium alloy core is one that contains a homogeneous phase of a palladium alloy in combination with one or more interlayers of palladium.
In another embodiment, the metal alloy core is a homogeneous or heterogeneous alloy of two or more metals selected from palladium, rhenium, gold, rhodium, iridium, ruthenium, and osmium. Some examples of such binary metal alloy compositions include the alloys of palladium-gold, palladium-rhodium, palladium-iridium, palladium-ruthenium, palladium-osmium, palladium-rhenium, rhodium-gold, iridium-gold, ruthenium-gold, osmium-gold, rhenium-gold, iridium-rhodium, ruthenium-rhodium, osmium-rhodium, rhenium-rhodium, ruthenium-iridium, osmium-iridium, rhenium-iridium, osmium-ruthenium, rhenium-ruthenium, and rhenium-osmium.
Particularly preferred binary alloy compositions for the metal alloy core are the rhenium-based compositions. Some preferred rhenium compositions are the rhenium-gold and rhenium-iridium compositions. The molar percentage of rhenium in these compositions is not particularly limited. For example, rhenium can be in a minimum amount of approximately 0.5, 1, 5, 10, 20, 30, or 40 molar percent, or in a maximum amount of approximately 50, 60, 70, 80, 90, 95, or 99 molar percent. Rhenium can be in any suitable range, and particularly, any suitable range resulting from a combination of the minimum and maximum molar percents described.
Some examples of ternary metal alloy compositions suitable for the metal alloy core include the homogeneous and heterogeneous alloys of palladium-gold-rhodium, palladium-rhodium-iridium, palladium-iridium-gold, palladium-ruthenium-rhodium, palladium-rhenium-gold, palladium-rhenium-iridium, palladium-rhenium-rhodium, palladium-rhenium-ruthenium, rhenium-rhodium-gold, rhenium-iridium-gold, rhenium-ruthenium-gold, rhenium-iridium-rhodium, rhenium-rhodium-ruthenium, rhenium-iridium-ruthenium, and rhenium-iridium-osmium.
In a further embodiment, the metal alloy core is composed of one or more zerovalent or charged second row (4d) and/or third row (5d) transition metals in combination with one or more first row (3d) transition metals. For example, the metal alloy core can be a homogeneous or heterogeneous alloy composed of, minimally, one or a combination of second row and/or third row transition metals in combination with one or a combination of first row transition metals.
The first row (3d) transition metals refer to the row of transition metals starting with scandium (Sc). Some examples of suitable first row transition metals include titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and zinc (Zn).
The second row (4d) transition metals refer to the row of transition metals starting with yttrium (Y). Some examples of suitable second row transition metals include molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag).
The third row (5d) transition metals refer to the row of transition metals starting with hafnium (Hf). Some examples of suitable third row transition metals include tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au).
The one or combination of second row and/or third row transition metals in the metal alloy core are preferably noble metals. Some examples of suitable noble metals include palladium, gold, rhodium, iridium, ruthenium, osmium, rhenium, and combinations thereof.
In a further embodiment, the metal alloy core is composed of one or a combination of zerovalent or charged second row and/or third row transition metal atoms in combination with one or a combination of first row transition metal atoms. The metal alloy core can be in the form of a binary, ternary, quaternary, pentenary, or higher alloy of any combination of these metals.
Preferably, the zerovalent or charged second row and/or third row transition metal atoms in the metal alloy core are selected from gold, rhodium, iridium, ruthenium, osmium, and rhenium.
Preferably, the first row transition metals in the metal alloy core are selected from nickel, cobalt, and iron. More preferably, at least a portion of the one or combination of first row transition metal atoms is zerovalent.
In one embodiment, the metal alloy core includes one second row or third row transition metal in combination with one first row transition metal to make a binary alloy composition. Such a binary alloy can be represented by the molar composition formulas M n T (1a) or MT p (1b) wherein M represents a second row or third row transition metal and T represents a first row transition metal.
In formulas (1a) and (1b), n and p independently represent an integer of 1 or above. In formula (1a), n represents the number of M metal atoms per T metal atoms, i.e., the ratio M:T of n:1. In formula (1b), p represents the number of T metal atoms per M metal atoms, i. e., the molar ratio T:M of p:1. The values of n in formula (1a) can range, for example, from approximately 1000 to 1.
For example, AuNi 10 represents a binary alloy having a molar composition of ten nickel atoms per gold atom. Au 2 Ni represents a binary alloy having a molar composition of two gold atoms per nickel atom. Similarly, Au 4 Ni represents a binary alloy having a molar composition of four gold atoms per nickel atom.
Alternatively, such a binary alloy composition can be represented by the molar percentage formula M 1−x T x (2a). Formula (2a) is related to formula (1a) in that x is a fractional number equivalent to 1/(n+1). Accordingly, Au 2 Ni according to formula (1a) corresponds approximately to Au 0.67 Ni 0.33 according to formula (2a). Similarly, Au 3 Ni corresponds to Au 0.75 Ni 0.25 (molar composition of 75% Au and 25% Ni) and Au 4 Ni corresponds to Au 0.8 Ni 0.2 (a molar composition of 80% Au and 20% Ni). Similarly, AuNi 10 corresponds approximately to Au 0.09 Ni 0.91 (molar composition of 9% Au and 91% Ni).
In formula (2a), the value of x is not particularly limited. For example, x can have a minimum value of about 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, or 0.5. Alternatively, x can have a maximum value of about 0.999, 0.99, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, or 0.55. Still further, x can be in a range governed by any suitable combination of such minimum and maximum values.
In one embodiment, the binary alloy composition of the metal alloy core is a combination of one second row transition metal and one first row transition metal. Some examples of classes of such binary alloy compositions suitable for the metal alloy core include the ruthenium-nickel, ruthenium-cobalt, ruthenium-iron, rhodium-nickel, rhodium-cobalt, and rhodium-iron classes of binary alloy compositions.
Some examples of ruthenium-nickel binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ru 0.01 Ni 0.99 , Ru 0.05 Ni 0.95 (e.g., RuNi 20 ), Ru 0.1 Ni 0.9 (e.g., RuNi 9 , RuNi 10 , and RuNi 11 ), Ru 0.2 Ni 0.8 , Ru 0.3 Ni 0.7 , Ru 033 Ni 0.67 (i.e., RuNi 2 ), Ru 0.4 Ni 0.6 , Ru 0.5 Ni 0.5 (i.e., RuNi), Ru 0.6 Ni 0.4 , Ru 0.66 Ni 0.33 (i.e., Ru 2 Ni), Ru 0.7 Ni 0.3 , Ru 0.75 Ni 0.25 (ie., Ru 3 Ni), Ru 0.8 Ni 0.2 (i.e., Ru 4 Ni), Ru 0.9 Ni 0.1 , and Ru 0.99 Ni 0.0 .
Some examples of ruthenium-cobalt binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ru 0.01 Co 0.99 , Ru 0.05 Co 0.95 (e.g., RuCo 20 ), Ru 0.1 Co 0.9 (e.g., RuCo 9 , RuCo 10 , and RuCo 11 ), Ru 0.2 Co 0.8 , Ru 0.3 Co 0.7 , Ru 0.33 Co 0.67 (i.e., RuCo 2 ), Ru 0.4 Co 0.6 , Ru 0.5 Co 0.5 (i.e., RuCo), Ru 0.6 Co 0.4 , Ru 0.67 Co 0.33 (i.e., Ru 2 Co), Ru 0.7 Co 0.3 , Ru 0.75 Co 0.25 (i.e., Ru 3 Co), Ru 0.8 Co 0.2 (i.e., Ru 4 Co), Ru 0.9 Co 0.1 , and Ru 0.99 Co 0.01 .
Some examples of ruthenium-iron binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ru 0.01 Fe 0.99 , Ru 0.05 Fe 0.95 (e.g., RuFe 20 ), Ru 0.1 Fe 0.9 (e.g., RuFe 9 , RuFe 10 , and RuFe 11 ), Ru 0.2 Fe 0.8 , Ru 0.3 Fe 0.7 , Ru 0.33 Fe 0.67 (i.e., RuFe 2 ), Ru 0.4 Fe 0.6 , Ru 0.5 Fe 0.5 (i.e., RuFe), Ru 0.6 Fe 0.4 , Ru 0.66 Fe 0.33 (i.e., Ru 2 Fe), Ru 0.7 Fe 0.3 , Ru 0.75 Fe 0.25 (i.e., Ru 3 Fe), Ru 0.8 Fe 0.2 (i.e., Ru 4 Fe), Ru 0.9 Fe 0.1 , and Ru 0.99 Fe 0.01 .
Some examples of rhodium-nickel binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Rh 0.01 Ni 0.99 , Rh 0.05 Ni 0.95 (e.g., RhNi 20 ), Rh 0.1 Ni 0.9 (e.g., RhNi 9 , RhNi 10 , and RhNi 11 ), Rh 0.2 Ni 0.8 , Rh 0.3 Ni 0.7 , Rh 0.33 Ni 0.67 (i.e., RhNi 2 ), Rh 0.4 Ni 0.6 , Rh 0.5 Ni 0.5 (i.e., RhNi), Rh 0.6 Ni 0.4 , Rh 0.66 Ni 0.33 (i.e., Rh 2 Ni), Rh 0.7 Ni 0.3 , Rh 0.75 Ni 0.25 (i.e., Rh 3 Ni), Rh 0.8 Ni 0.2 (i.e., Rh 4 Ni), Rh 0.9 Ni 0.1 , and Rh 0.99 Ni 0.01 .
Some examples of rhodium-cobalt binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Rh 0.01 Co 0.99 , Rh 0.05 Co 0.95 (e.g., RhCo 20 ), Rh 0.1 Co 0.9 (e.g., RhCo 9 , RhCo 10 , and RhCo 11 ), Rh 0.2 Co 0.8 , Rh 0.3 Co 0.7 , Rh 0.33 Co 0.67 (i.e., RhNi 2 ), Rh 0.4 Co 0.6 , Rh 0.5 Co 0.5 (i.e., RhCo), Rh 0.6 Co 0.4 , Rh 0.66 Co 0.33 (i.e., Rh 2 Co), Rh 0.7 Co 0.3 , Rh 0.75 Co 0.25 (i.e., Rh 3 Co), Rh 0.8 Co 0.2 (i.e., Rh 4 Co), Rh 0.9 Co 0.1 , and Rh 0.99 Co 0.01 .
Some examples of rhodium-iron binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Rh 0.01 Fe 0.99 , Rh 0.05 Fe 0.95 (e.g., RhFe 20 ), Rh 0.1 Fe 0.9 (e.g., RhFe 9 , RhFe 10 , and RhFe 11 ), Rh 0.2 Fe 0.8 , Rh 0.3 Fe 0.7 , Rh 0.33 Fe 0.67 (i.e., RhFe 2 ), Rh 0.4 Fe 0.6 , Rh 0.5 Fe 0.5 (i.e., RhFe), Rh 0.6 Fe 0.4 , Rh 0.66 Fe 0.33 (i.e., Rh 2 Fe), Rh 0.7 Fe 0.3 , Rh 0.75 Fe 0.25 (i.e., Rh 3 Fe), Rh 0.8 Fe 0.2 (i.e., Rh 4 Fe), Rh 0.9 Fe 0.1 , and Rh 0.99 Fe 0.01 .
In another embodiment, the binary alloy composition of the metal alloy core is a combination of one third row transition metal and one first row transition metal. Some examples of classes of such binary alloy compositions suitable for the metal alloy core include the gold-nickel, gold-cobalt, gold-iron, rhenium-nickel, rhenium-cobalt, rhenium-nickel, iridium-nickel, iridium-cobalt, iridium-iron, osmium-nickel, osmium-cobalt, and osmium-iron classes of binary alloy compositions.
Some examples of gold-nickel binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Au 0.01 Ni 0.99 , Au 0.05 Ni 0.95 (e.g., AuNi 20 ), Au 0.1 Ni 0.9 (e.g., AuNi 9 , AuNi 10 , and AuNi 11 ), Au 0.2 Ni 0.8 , Au 0.3 Ni 07 , Au 0.33 Ni 0.67 (ie., AuNi 2 ), Au 0.4 Ni 0.6 , Au 0.5 Ni 0.5 (i.e., AuNi), Au 0.6 Ni 0.4 , Au 0.66 Ni 0.33 (i.e., Au 2 Ni), Au 0.7 Ni 0.3 , Au 0.75 Ni 0.25 (i.e., Au 3 Ni), Au 0.8 Ni 0.2 (ie., Au 4 Ni), Au 0.9 Ni 0.1 , and Au 0.99 Ni 0.01 .
Some examples of gold-cobalt binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Au 0.01 Co 0.99 , Au 0.05 Co 0.95 (e.g., AuCo 20 ), Au 0.1 Co 0.9 (e.g., AuCo 9 , AuCo 10 , and AuCo 11 ), Au 0.2 Co 0.8 , Au 0.3 Co 0.7 , Au 0.33 Co 0.67 (i.e., AuCo 2 ), Au 0.4 Co 0.6 , Au 0.5 Co 0.5 (i.e., AuCo), Au 0.6 Co 0.4 , Au 0.67 Co 0.33 (i.e., Au 2 Co), Au 0.7 Co 0.3 , Au 0.75 Co 0.25 (i.e., Au 3 Co), Au 0.8 Co 0.2 (i.e., Au 4 Co), Au 0.9 Co 0.1 , and Au 0.99 Co 0.01 .
Some examples of gold-iron binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Au 0.01 Fe 0.99 , Au 0.05 Fe 0.95 (e.g., AuFe 20 ), Au 0.1 Fe 0.9 (e.g., AuFe 9 , AuFe 10 , and AuFe 11 ), Au 0.2 Fe 0.8 , Au 0.3 Fe 0.7 , Au 0.33 Fe 0.67 (i.e., AuFe 2 ), Au 0.4 Fe 0.6 , Au 0.5 Fe 0.5 (i.e., AuFe), Au 0.6 Fe 0.4 , Au 0.66 Fe 0.33 (i.e., Au 2 Fe), Au 0.7 Fe 0.3 , Au 0.75 Fe 0.25 (i.e., Au 3 Fe), Au 0.8 Fe 0.2 (i.e., Au 4 Fe), Au 0.9 Fe 0.1 , and Au 0.99 Fe 0.01 .
Some examples of rhenium-nickel binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Re 0.01 Ni 0.99 , Re 0.05 Ni 0.95 (e.g., ReNi 20 ), Re 0.1 Ni 0.9 (e.g., ReNi 9 , ReNi 10 , and ReNi 11 ), Re 0.2 Ni 0.8 , Re 0.3 Ni 0.7 , Re 0.33 Ni 0.67 (i.e., ReNi 2 ), Re 0.4 Ni 0.6 , Re 0.5 Ni 0.5 (i.e., ReNi), Re 0.6 Ni 0.4 , Re 0.66 Ni 0.33 (i.e., Re 2 Ni), Re 0.7 Ni 0.3 , Re 0.75 Ni 0.25 (i.e., Re 3 Ni), Re 0.8 Ni 0.2 (i.e., Re 4 Ni), Re 0.9 Ni 0.1 , and Re 0.99 Ni 0.01 .
Some examples of rhenium-cobalt binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Re 0.01 Co 0.99 , Re 00.5 Co 0.95 (e.g., ReCo 20 ), Re 0.1 Co 0.9 (e.g., ReCo 9 , ReCo 10 , and ReCo 11 ), Re 0.2 Co 0.8 , Re 0.3 Co 0.7 , Re 0.33 Co 0.67 (i.e., ReCo 2 ), Re 0.4 Co 0.6 , Re 0.5 Co 0.5 (i e., ReCo), Re 0.6 Co 0.4 , Re 0.67 Co 0.33 (i.e., Re 2 Co), Re 0.7 Co 0.3 , Re 0.75 Co 0.25 (i.e., Re 3 Co), Re 0.8 Co 0.2 (i.e., Re 4 Co), Re 0.9 Co 0.1 , and Re 0.99 Co 0.01 .
Some examples of rhenium-iron binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Re 0.01 Fe 0.99 , Re 0.05 Fe 0.95 (e.g., ReFe 20 ), Re 0.01 Fe 0.9 (e.g., ReFe 9 , ReFe 10 , and ReFe 11 ), Re 0.2 Fe 0.8 , Re 03 Fe 07 , Re 033 Fe 0.67 (i.e., ReFe 2 ), Re 0.4 Fe 0.6 , Re 0.5 Fe 0.5 (i.e., ReFe), Re 0.6 Fe 0.4 , Re 0.66 Fe 0.33 (i.e., Re 2 Fe), Re 0.7 Fe 0.3 , Re 0.75 Fe 0.25 (i.e., Re 3 Fe), Re 0.8 Fe 0.2 (i.e., Re 4 Fe), Re 0.9 Fe 0.1 , and Re 0.99 Fe 0.01 .
Some examples of iridium-nickel binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ir 0.01 Ni 0.99 , Ir 0.05 Ni 0.95 (e.g., IrNi 20 ), Ir 0.1 Ni 0.9 (e.g., IrNi 9 , IrNi 10 , and IrNi 11 ), Ir 0.2 Ni 0.8 , Ir 0.3 Ni 0.7 , Ir 0.33 Ni 0.67 (i.e., IrNi 2 ), Ir 0.4 Ni 0.6 , Ir 0.5 Ni 0.5 (i.e., IrNi), Ir 0.6 Ni 0.4 , Ir 0.66 Ni 0.33 (i.e., Ir 2 Ni), Ir 0.7 Ni 0.3 , Ir 0.75 Ni 0.25 (i.e., Ir 3 Ni), Ir 0.8 Ni 0.2 (i.e., Ir 4 Ni), Ir 0.9 Ni 0.1 , and Ir 0.99 Ni 0.01 .
Some examples of iridium-cobalt binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ir 0.01 Co 0.99 , Ir 0.05 Co 0.95 (e.g., IrCo 20 ), Ir 0.1 Co 0.9 (e.g., IrCo 9 , IrCo 10 , and IrCo 11 ), Ir 0.2 Co 0.8 , Ir 0.3 Co 0.7 , Ir 0.33 Co 0.67 (i.e., IrCo 2 ), Ir 0.4 Co 0.6 , Ir 0.5 Co 0.5 (i.e., IrCo), Ir 0.6 Co 0.4 , Ir 0.67 Co 0.33 (i.e., Ir 2 Co), Ir 0.7 Co 0.3 , Ir 0.75 Co 0.25 (i.e., Ir 3 Co), Ir 0.8 Co 0.2 (i.e., Ir 4 Co), Ir 0.9 Co 0.1 , and Ir 0.99 Co 0.01 .
Some examples of iridium-iron binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ir 0.01 Fe 0.99 , Ir 0.05 Fe 0.95 (e.g., IrFe 20 ), Ir 0.1 Fe 0.9 (e.g., IrFe 9 , IrFe 10 , and IrFe 11 ), Ir 0.2 Fe 0.8 , Ir 0.3 Fe 0.7 , Ir 0.33 Fe 0.67 (i.e., IrFe 2 ), Ir 0.4 Fe 0.6 , Ir 0.5 Fe 0.5 (i.e., IrFe), Ir 0.6 Fe 0.4 , Ir 0.66 Fe 0.33 (i.e., Ir 2 Fe), Ir 0.7 Fe 0.3 , Ir 0.75 Fe 0.25 (i.e., Ir 3 Fe), Ir 0.8 Fe 0.2 (i.e., Ir 4 Fe), Ir 0.9 Fe 0.1 , and Ir 0.99 Fe 0.01 .
Some examples of osmium-nickel binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Os 0.01 Ni 0.99 , Os 0.05 Ni 0.95 (e.g., OsNi 20 ), Os 0.1 Ni 0.9 (e.g., OsNi 9 , OsNi 10 , and OsN 11 ), Os 0.2 Ni 0.8 , Os 0.3 Ni 0.7 , Os 0.33 Ni 0.67 (i.e., OsNi 2 ), Os 0.4 Ni 0.6 , Os 0.5 Ni 0.5 (ie., OsNi), Os 0.6 Ni 0.4 , Os 0.66 Ni 0.33 (i.e., Os 2 Ni), Os 0.7 Ni 0.3 , Os 0.75 Ni 0.25 (i.e., Os 3 Ni), Os 0.8 Ni 0.2 (ie., Os 4 Ni), Os 0.9 Ni 0.1 , and Os 0.99 Ni 0.01 .
Some examples of osmium-cobalt binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Os 0.01 Co 0.99 , Os 0.05 Co 0.95 (e.g., OsCo 20 ), Os 0.1 Co 0.9 (e.g., OsCo 9 , OsCo 10 , and OsCo 11 ), Os 0.2 Co 0.8 , Os 0.3 Co 0.7 , Os 0.33 Co 0.67 (i.e., OsCo 2 ), Os 0.4 Co 0.6 , Os 0.5 Co 0.5 (i.e., OsCo), Os 0.6 Co 0.4 , Os 0.67 Co 0.33 (i.e., Os 2 Co), Os 0.7 Co 0.3 , Os 0.75 Co 0.25 (i.e., Os 3 Co), Os 0.8 Co 0.2 (i.e., Os 4 Co), Os 0.9 Co 0.1 , and Os 0.99 Co 0.01 .
Some examples of osmium-iron binary alloy compositions suitable for the metal alloy core include the approximate molar compositions Os 0.01 Fe 0.99 , Os 0.05 Fe 0.95 (e.g., OsFe 20 ), Os 0.1 Fe 0.9 (e.g., OsFe 9 , OsFe 10 , and OsFe 11 ), Os 0.2 Fe 0.8 , Os 0.3 Fe 0.7 , Os 0.33 Fe 0.67 (i.e., OsFe 2 ), Os 0.4 Fe 0.6 , Os 0.5 Fe 0.5 (i.e., OsFe), Os 0.6 Fe 0.4 , Os 0.66 Fe 0.33 (i.e., Os 2 Fe), Os 0.7 Fe 0.3 , Os 0.75 Fe 0.25 (i.e., Os 3 Fe), Os 0.8 Fe 0.2 (i.e., Os 4 Fe), Os 0.9 Fe 0.1 , and Os 0.99 Fe 0.0 .
In another embodiment, the metal alloy core is in the form of a ternary alloy composition. Such a ternary alloy composition can be represented by the molar composition formula M 1−x−y N x T y (3a) wherein one or two of M, N, and T independently represent second row or third row transition metals and one or two of M, N, T independently represent first row transition metals. The values of x and y are independently as described for x above under formula (2a). By the rules of chemistry, the sum of x and y in formula (3a) must be less than 1.
In one embodiment, the metal alloy core is in the form of a ternary alloy composition having two second row transition metals and one first row transition metal. Some examples of classes of such ternary alloy compositions suitable for the metal alloy core include the ruthenium-rhodium-nickel, ruthenium-rhodium-cobalt, and ruthenium-rhodium-iron classes of ternary alloy compositions.
Some examples of ruthenium-rhodium-nickel ternary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ru 0.025 Rh 0.025 Ni 0.95 , Ru 0.05 Rh 0.05 Ni 0.9 Ru 0.1 Rh 0.1 Ni 0.8 , Ru 0.1 Rh 0.2 Ni 0.7 , Ru 0.2 Rh 0.1 Ni 0.7 , Ru 0.2 Rh 0.2 Ni 0.6 , Ru 0.3 Rh 0.1 Ni 0.6 , Ru 0.1 Rh 0.3 Ni 0.6 , Ru 0.25 Rh 0.25 Ni 0.5 (i.e., RuRhNi 2 ), Ru 0.4 Rh 0.1 Ni 0.5 , Ru 0.1 Rh 0.4 Ni 0.5 , Ru 0.3 Rh 0.3 Ni 0.4 , Ru 0.4 Rh 0.2 Ni 0.4 , Ru 0.2 Rh 0.4 Ni 0.4 , Ru 0.33 Rh 0.33 Ni 0.33 (i e., RuRhNi), Ru 0.3 Rh 0.4 Ni 0.3 , Ru 0.5 Rh 0.2 Ni 0.3 , Ru 0.2 Rh 0.5 Ni 0.3 , Ru 0.6 Rh 0.1 Ni 0.3 , Ru 0.1 Rh 0.6 Ni 0.3 , Ru 0.4 Rh 0.4 Ni 0.2 Ru 0.6 Rh 0.2 Ni 0.2 , Ru 0.2 Rh 0.6 Ni 0.2 , Ru 0.45 Rh 0.45 Ni 0.1 , Ru 0.6 Rh 0.3 Ni 0.1 , Ru 0.3 Rh 0.6 Ni 0.1 , Ru 0.8 Rh 0.1 Ni 0.1 , and Ru 0.1 Rh 0.8 Ni 0.1 .
Some examples of ruthenium-rhodium-cobalt ternary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ru 0.025 Rh 0.025 Co 0.95 , Ru 0.05 Rh 0.05 Co 0.9 , Ru 0.1 Rh 0.1 Co 0.8 , Ru 0.1 Rh 0.2 Co 0.7 , Ru 0.2 Rh 0.1 Co 0.7 , Ru 0.2 Rh 0.2 Co 0.6 , Ru 0.3 Rh 0.1 Co 0.6 , Ru 0.1 Rh 0.3 Co 0.6 , Ru 0.25 Rh 0.25 Co 0.5 (i.e., RuRhCo 2 ), Ru 0.4 Rh 0.1 Co 0.5 , Ru 0.1 Rh 0.4 Co 0.5 , Ru 0.3 Rh 0.3 Co 0.4 , Ru 0.4 Rh 0.2 Co 0.4 , Ru 0.2 Rh 0.4 Co 0.4 Ru 0.33 Rh 0.33 Co 0.33 (i.e., RuRhCo), Ru 0.3 Rh 0.4 Co 0.3 , Ru 0.5 Rh 0.2 Co 0.3 , Ru 0.2 Rh 0.5 Co 0.3 , Ru 0.6 Rh 0.1 Co 0.3 , Ru 0.1 Rh 0.6 Co 0.3 , Ru 0.4 Rh 0.4 Co 0.2 , Ru 0.6 Rh 0.2 Co 0.2 , Ru 0.2 Rh 0.6 Co 0.2 , Ru 0.45 Rh 0.45 Co 0.1 , Ru 0.6 Rh 0.3 Co 0.1 , Ru 0.3 Rh 0.6 Co0.1, Ru 0.8 Rh 0.1 Co 0.1 , and Ru 0.1 Rh 0.8 Co 0.1 .
Some examples of ruthenium-rhodium-iron ternary alloy compositions suitable for the metal alloy core include the approximate molar compositions Ru 0.025 Rh 0.025 Fe 0.95 , Ru 0.05 Rh 0.05 Fe 0.9 , Ru 0.1 Rh 0.1 Fe 0.8 , Ru 0.1 Rh 0.2 Fe 0.7 , Ru 0.2 Rh 0.1 Fe 0.7 , Ru 0.2 Rh 0.2 Fe 0.6 , Ru 0.3 Rh 0.1 Fe 0.6 , Ru 0.1 Rh 0.3 Fe 0.6 , Ru 0.25 Rh 0.25 Fe 0.5 (i.e., RuRhFe 2 ), Ru 0.4 Rh 0.1 Fe 0.5 , Ru 0.1 Rh 0.4 Fe 0.5 , Ru 0.3 Rh 0.3 Fe 0.4 , Ru 0.4 Rh 0.2 Fe 0.4 , Ru 0.2 Rh 0.4 Fe 0.4 , Ru 0.33 Rh 0.33 Fe 0.33 (i e., RuRhFe), Ru 0.3 Rh 0.4 Fe 0.3 , Ru 0.5 Rh 0.2 Fe 0.3 , Ru 0.2 Rh 0.5 Fe 0.3 , Ru 0.6 Rh 0.1 Fe 0.3 , Ru 0.1 Rh 0.6 Fe 0.3 , Ru 0.4 Rh 0.4 Fe 0.2 , Ru 0.6 Rh 0.2 Fe 0.2 , Ru 0.2 Rh 0.6 Fe 0.2 , Ru 0.45 Rh 0.45 Fe 0.1 , Ru 0.6 Rh 0.3 Fe 0.1 , Ru 0.3 Rh 0.6 Fe 0.1 , Ru 0.8 Rh 0.1 Fe 0.1 , and Ru 0.1 Rh 0.8 Fe 0.1 .
In another embodiment, the metal alloy core is in the form of a ternary alloy composition having two third row transition metals and one first row transition metal. Some examples of classes of such ternary alloy compositions suitable for the metal alloy core include the gold-rhenium-nickel, gold-rhenium-cobalt, gold-rhenium-iron, gold-iridium-nickel, gold-iridium-cobalt, gold-iridium-iron, gold-osmium-nickel, gold-osmium-cobalt, gold-osmium-iron, rhenium-iridium-nickel, rhenium-iridium-cobalt, rhenium-iridium-iron, rhenium-osmium-nickel, rhenium-osmium-cobalt, rhenium-osmium-iron, iridium-osmium-nickel, iridium-osmium-cobalt, and iridium-osmium-iron classes of ternary alloy compositions.
Some examples of gold-rhenium-nickel ternary alloy compositions suitable for the metal alloy core include the approximate molar compositions Au 0.025 Re 0.025 Ni 0.95 , Au 0.05 Re 0.05 Ni 0.9 , Au 0.1 Re 0.1 Ni 0.8 , Au 0.1 Re 0.2 Ni 0.7 , Au 0.2 Re 0.1 Ni 0.7 , Au 0.2 Re 0.2 Ni 0.6 , Au 0.3 Re 0.1 Ni 0.6 , Au 0.1 Re 0.3 Ni 0.6 , Au 0.25 Re 0.25 Ni 0.5 (i.e., AuReNi 2 ), Au 0.4 Re 0.1 Ni 0.5 , Au 0.1 Re 0.4 Ni 0.5 , Au 0.3 Re 0.3 Ni 0.4 , Au 0.4 Re 0.2 Ni 0.4 , Au 0.2 Re 0.4 Ni 0.4 , Au 0.33 Re 0.33 Ni 0.33 (i.e., AuReNi), Au 0.3 Re 0.4 Ni 0.3 , Au 0.5 Re 0.2 Ni 0.3 , Au 0.2 Re 0.5 Ni 0.3 , Au 0.6 Re 0.1 Ni 0.3 , Au 0.1 Re 0.6 Ni 0.3 , Au 0.4 Re 0.4 Ni 0.2 , Au 0.6 Re 0.2 Ni 0.2 , Au 0.2 Re 0.6 Ni 0.2 , Au 0.45 Re 0.45 Ni 0.1 , Au 0.6 Re 0.3 Ni 0.1 , Au 0.3 Re 0.6 Ni 0.1 , Au 0.8 Re 0.1 Ni 0.1 , and Au 0.1 Re 0.8 Ni 0.1 .
Some examples of gold-rhenium-cobalt ternary alloy compositions suitable for the metal alloy core include the approximate molar compositions Au 0.025 Re 0.025 Co 0.95 , Au 0.05 Re 0.05 Co 0.9 , Au 0.1 R 0.1 Co 0.8 , Au 0.1 Re 0.2 Co 0.7 , Au 0.2 Re Co 0.7 , Au 0.2 Re 0.2 Co 0.6 , Au 0.3 Re 0.1 Co 0.6 , Au 0.1 Re 0.3 Co 0.6 , Au 0.25 Re 0.25 Co 0.5 (i.e., AuReCo 2 ), Au 0.4 Re 0.1 Co 0.5 , Au 0.1 Re 0.4 Co 0.5 , Au 0.3 Re 0.3 Co 0.4 , Au 0.4 Re 0.2 Co 0.4 , Au 0.2 Re 0.4 Co 0.4 , Au 0.33 Re 0.33 Co 0.33 (i.e., AuReCo), Au 0.3 Re 0.4 Co 0.3 , Au 0.5 Re 0.2 Co 0.3 , Au 0.2 Re 0.5 Co 0.3 , Au 0.6 Re 0.1 Co 0.3 , Au 0.1 Re 0.6 Co 0.3 , Au 0.4 Re 0.4 Co 0.2 , Au 0.6 Re 0.2 C 0 0.2 , Au 0.2 Re 0.6 Co 0.2 , Au 0.45 Re 0.45 Co 0.1 , Au 0.6 Re 0.3 Co 0.1 , Au 0.3 Re 0.6 Co 0.1 , Au 0.8 Re 0.1 Co 0.1 , and Au 0.1 Re 0.8 Co 0.1 .
Some examples of gold-rhenium-iron ternary alloy compositions suitable for the metal alloy core include the approximate molar compositions Au 0.025 Re 0.025 Fe 0.95 , Au 0.05 Re 0.05 Fe 0.9 , Au 0.1 Re 0.1 Fe 0.8 , Au 0.1 Re 0.2 Fe 0.7 , Au 0.2 Re 0.1 Fe 0.7 , Au 0.2 Reo 0.2 Fe 0.6 , Au 0.3 Re 0.1 Fe 0.6 , Au 0.1 Re 0.3 Fe 0.6 , Au 0.25 Re 0.25 Fe 0.5 (i.e., AuReFe 2 ), Au 0.4 Re 0.1 Fe 0.5