Methods of synthesizing ultrafine nano-alloys and fabricating powder precursors for use therein

Abstract

Synthesis of ultrafine nano-alloys and powder precursors for use in the synthesis of ultrafine nano-alloys. A powder precursor is formed of metal salts on particles of a carbonaceous support, and then laser irradiated with a plurality of laser pulses delivered at a high frequency to reduce metal ions of the metal salt in the powder precursor to metal atoms and form the ultrafine nano-alloy.

1 . A method of synthesizing an ultrafine nano-alloy, the method comprising:
 providing a powder precursor formed of powder grains comprising at least one metal salt on particles of a carbonaceous support; and   laser irradiating the powder precursor with a plurality of laser pulses delivered at a high frequency to reduce metal atoms in the powder precursor to form the ultrafine nano-alloy.   
     
     
         2 . The method of  claim 1 , wherein the step of laser irradiating is conducted in air at standard atmospheric pressure. 
     
     
         3 . The method of  claim 1 , further comprising removing residual metal salts from the ultrafine nano-alloy. 
     
     
         4 . The method of  claim 3 , wherein the step of removing comprises dissolving the residual metal salts in a liquid solvent. 
     
     
         5 . The method of  claim 1 , wherein the high frequency is in the range of about 1-100 nanoseconds. 
     
     
         6 . The method of  claim 1 , wherein the powder grains comprise 1-11 different metal salts supported on the particles of the carbonaceous support. 
     
     
         7 . The method of  claim 1 , wherein the particles of the carbonaceous support comprise at least one of graphene and carbon nanotubes (CNTs). 
     
     
         8 . The method of  claim 1 , further comprising cooling the ultrafine nano-alloy immediately after reducing the metal atoms with the laser pulses. 
     
     
         9 . The method of  claim 1 , wherein the laser pulses provide a dose of about 1 to 10 pulses per mg of the powder precursor. 
     
     
         10 . The method of  claim 1 , wherein the step of providing the powder precursor comprises:
 wet-impregnating the at least one metal salt on the particles of the carbonaceous support to form a precursor slurry; and   drying the slurry to form the powder precursor.   
     
     
         11 . A method of fabricating a powder precursor for synthesizing an ultrafine nano-alloy, the powder precursor being formed of powder grains comprising at least one metal salt on particles of a carbonaceous support, the method comprising:
 dissolving the at least one metal salt in a liquid solvent;   adding the particles of a carbonaceous support to the dissolved at least one metal salt and liquid solvent;   dispersing the particles of the carbonaceous support in the dissolved at least one metal salt and liquid solvent to form a dispersion solution; and   drying and degassing the dispersion solution to form the powder precursor.   
     
     
         12 . The method of  claim 11 , wherein the liquid solvent comprises ethanol. 
     
     
         13 . The method of  claim 11 , wherein the step of dissolving comprises sonicating the at least one metal salt in the liquid solvent. 
     
     
         14 . The method of  claim 11 , wherein the step of dissolving comprises dissolving a plurality of different metal salts in the liquid solvent. 
     
     
         15 . The method of  claim 11 , wherein the step of dissolving comprises dissolving from 1 to 11 different metal salts in the liquid solvent. 
     
     
         16 . The method of  claim 11 , wherein the particles of the carbonaceous support comprise at least one of graphene flakes and carbon nanotubes. 
     
     
         17 . The method of  claim 11 , wherein the step of dispersing comprises sonicating the particles of the carbonaceous support in the dissolved metal salt and liquid solvent.