Au-Pt heteroaggregate dendritic nanostructures and Au-Pt alloy nanoparticles and their use as catalysts
Au—Pt heteroaggregate dendritic nanostructures and AuPt alloy nanoparticles, and their use as anodic catalysts in fuel cells.
1. A method of preparing metastable binary alloy nanoparticles comprising first and second metallic elements, which method comprises:
a) co-dissolving and co-reducing soluble salts of said first and second metallic elements in an inert solvent using a reducing agent sufficiently strong to simultaneously co-reduce said soluble salts of said first and second metallic elements at a temperature sufficient to form a metastable binary alloy colloid;
b) cooling the formed metastable binary alloy colloid to ambient temperature; and
c) diluting the colloid with a polar organic solvent to deposit metastable binary metal alloy nanoparticles.
2. The method of claim 1 , wherein said first metal is Au, and said second metal is Pt.
3. The method of claim 1 , wherein said first metal is Au, and said second metal is Ni.
4. The method of claim 1 , wherein said inert solvent is a hydrocarbon.
5. The method of claim 4 , wherein said hydrocarbon is decahydronaphthalene.
6. The method of claim 1 , wherein the polar organic solvent is ethanol.
7. The method of claim 1 , wherein all solvent is removed by centrifuge.
8. The method of claim 1 , wherein said temperature sufficient to form a metastable binary alloy colloid in step a) is in excess of 100° C.
9. The method of claim 8 , wherein said temperature is in a range of from 200-250° C.
10. The method of claim 1 , wherein said reducing agent in step a) is n-butyllithium.
11. The method of claim 1 , wherein said reducing agent in step a) is sodium naphthalide.
12. The method of claim 1 , wherein said reducing agent in step a) is potassium naphthalide.
13. The method of claim 1 , wherein said first metal is Au, and said second metal is selected from the group consisting of W and Rh.
14. The method of claim 1 , wherein said metastable binary alloy nanoparticles produced are PtW.
15. The method of claim 1 , wherein the metastable binary alloy nanoparticles have a size of from 1 nm to 30 nm.
16. The method of claim 1 , which further comprises after step c), redispersing the deposited metastable binary alloy nanoparticles in a solvent and a surfactant.
17. The method of claim 16 , wherein the surfactant comprises oleic acid and oleylamine.
18. The method of claim 16 , wherein the solvent is toluene.