Method for production of metal skin layer particles with controllable layer thickness

Abstract

A method of depositing at least one metal skin layer on a metal nanoparticle core is disclosed. The first step of the method is selecting a metal to deposit. Then, the metal nanoparticle core is dispersed in an electrolyte solvent to form a liquid mixture. Next, a hydrogen containing gas is bubbled through the liquid mixture to form a layer of adsorbed hydrogen atoms on the surface of the metal nanoparticle core. Finally, the selected metal is added to the liquid mixture to form a metal skin layer on the metal nanoparticle core.

What is claimed is: 
     
         1 . A method of depositing at least one metal skin layer on a metal nanoparticle core comprising the steps of:
 a. selecting a metal to deposit;   b. dispersing the metal nanoparticle core in an electrolyte solvent to form a liquid mixture;   c. bubbling a hydrogen containing gas through the liquid mixture to form a layer of adsorbed hydrogen atoms on the surface of the metal nanoparticle core; and   d. adding the selected metal to the liquid mixture to form a metal skin layer on the metal nanoparticle core   
     
     
         2 . The method of  claim 1 , wherein the selected metal is incapable of adsorbing and dissociating hydrogen molecules (M I ). 
     
     
         3 . The method of  claim 1 , wherein the selected metal is capable of adsorbing and dissociating hydrogen molecules (M C ). 
     
     
         4 . The method of  claim 3 , wherein prior to step d the method further comprises the steps of:
 a. adding a metal ion or metal ion complex (M R ) to the liquid mixture wherein M R  is reduced by the adsorbed hydrogen atoms to form a layer of M R  on the metal nanoparticle core; and   b. purging the liquid mixture of all excess hydrogen.   
     
     
         5 . The method of  claim 4 , wherein the entire method is repeated multiple times so as to deposit multiple layers of M C . 
     
     
         6 . The method of  claim 2 , wherein prior to step d the method further comprises the steps of:
 a. adding a M R  to the liquid mixture wherein M R  is reduced by the adsorbed hydrogen atoms to form a layer of M R  on the metal nanoparticle core;   b. purging the liquid mixture of all excess hydrogen; and   c. adding a M C  to the liquid mixture.   
     
     
         7 . The method of  claim 6 , wherein every step prior to step d is repeated multiple times so as to deposit multiple layers of M C , and then once step d occurs; the added M I  will replace the multiple layers of M C  to form multiple layers of M I . 
     
     
         8 . The method of  claim 2 , wherein M I  is selected from the Group 11 through Group 15 metals of the Periodic Table. 
     
     
         9 . The method of  claim 3 , wherein M C  is selected from the Group 3 to Group 10 metals of the Periodic Table. 
     
     
         10 . The method of  claim 1 , wherein the metal nanoparticle core is selected from the Group 3 to Group 10 metals of the Periodic Table. 
     
     
         11 . The method of  claim 1 , wherein the electrolyte solvent is selected from any solvent capable of dissolving metal salts. 
     
     
         12 . The method of  claim 11 , wherein the electrolyte solvent is selected from the group consisting of water, methanol, ethanol, propanol, organic electrolytes and ionic liquids. 
     
     
         13 . The method of  claim 4 , wherein M R  is selected from M R 's that can undergo a reduction reaction wherein the reduced form of the M R  is a metal in solid form. 
     
     
         14 . The method of  claim 6 , wherein M R  is selected from M R 's that can undergo a reduction reaction wherein the reduced form of the M R  is a metal in solid form. 
     
     
         15 . The method of  claim 1 , wherein the hydrogen containing gas is selected from pure hydrogen gas or a mixture of hydrogen gas with other gases selected from nitrogen, argon, carbon dioxide, and carbon monoxide. 
     
     
         16 . The method of  claim 1 , wherein the temperature of the liquid mixture is less than about 100° C. 
     
     
         17 . The method of  claim 1 , wherein the pH of the liquid mixture is between about 0 and about 14.