Process of making metal nanoparticles
A process is described for making metal nanoparticles comprising (a) forming a liquid melt of a first metal having the composition of the desired nanoparticles and a second metal; (b) quenching the melt to form a solid; and (c) removing the second metal from the solid and forming the nanoparticles comprising the first metal.
1. A method of making nanoparticles comprising a first metal comprising:
a) forming a melt comprising the first metal and a second metal;
b) directly contacting the melt with a cooled solid surface to quench the melt and thereby form a substantially homogeneous solid; and
c) removing the second metal from the substantially homogeneous solid by solubilizing the second metal in a leaching agent to form nanoparticles comprising the first metal.
2. The process of claim 1 further comprising isolating the nanoparticles.
3. The process of claim 2 further comprising coating the nanoparticles.
4. The process of claim 1 wherein the melt comprises metals that form a solution in the melted state.
5. The process of claim 1 wherein the first metal and the second metal are provided as elemental metals or contributed by metal oxides, metal sulfides, metal nitrides, metal halides, metal salts, or combinations thereof.
6. The process of claim 5 wherein the metal of the first metal or the second metal is platinum, iridium, gold, silver, aluminum, magnesium, palladium, rhodium, ruthenium, titanium, osmium, rhenium, copper, nickel, cobalt, iron, indium, tin, zinc, neodymium, boron or combinations thereof.
7. The process of claim 6 wherein the metal component of the first metal is silver or a silver-copper alloy.
8. The process of claim 1 wherein the second metal is hydroxide soluble.
9. The process of claim 8 wherein the second metal is aluminum, magnesium or calcium.
10. The process of claim 1 wherein the second metal is removed by leaching with a hydroxide.
11. The process of claim 10 wherein the hydroxide is sodium hydroxide or potassium hydroxide.
12. The process of claim 1 wherein the first metal is silver and the second metal is aluminum.
13. The process of claim 12 wherein the silver is less than 80 percent by weight of the melt.
14. The process of claim 13 wherein the silver is less than 60 percent by weight of the melt.
15. The process of claim 14 wherein the silver is less than 50 percent by weight of the melt.
16. The process of claim 1 wherein the melt is quenched to a temperature less than 80° C.
17. The process of claim 16 wherein the melt is quenched to a temperature less than 50° C.
18. The process of claim 17 wherein the melt is quenched to a temperature less than 40° C.
19. The process of claim 1 wherein the rate of quenching is greater than 1000° C. per second.