Method for converting metal with relative low reduction potential into metal with relative high reduction potential without changing its shape

Abstract

A method for converting a metal with a relative low reduction potential into a metal with a relative high reduction potential without changing its shape is disclosed, which comprises the following steps: providing a first metal substrate and a reaction solution comprising a second metal precursor, a cation surfactant, and a weak reducing agent; and placing the first metal substrate into the reaction solution for a predetermined time to convert the first metal substrate into a second metal substrate. Herein, the reduction potential of a first metal of the first metal substrate is lower than that of a second metal of the second metal substrate, and the shapes of the first metal substrate and the second metal substrate are the same.

What is claimed is: 
     
         1 . A method for converting a first metal with relative low reduction potential into a second metal with relative high reduction potential, comprising:
 providing a first metal substrate and a reaction solution comprising a second metal precursor, a cation surfactant, and a weak reducing agent; and   placing the first metal substrate into the reaction solution for a predetermined time to convert the first metal substrate into a second metal substrate,   wherein the reduction potential of a first metal of the first metal substrate is lower than that of a second metal of the second metal substrate and the second metal precursor, and shapes of the first metal substrate and the second metal substrate are the same.   
     
     
         2 . The method as claimed in  claim 1 , wherein the cation surfactant is represented by the following formula (I): 
       
         
           
           
               
               
           
         
       
       wherein each R 1 , R 2 , and R 3  independently is C 1-3  alkyl, R 4  is C 12-22  alkyl, and X −  is a halogen ion. 
     
     
         3 . The method as claimed in  claim 2 , wherein X −  is F − , Cl − , or Br − . 
     
     
         4 . The method as claimed in  claim 2 , wherein each R 1 , R 2 , and R 3  independently is methyl or ethyl, and R 4  is C 14-20  alkyl. 
     
     
         5 . The method as claimed in  claim 2 , wherein the cation surfactant is cetyltrimethylammonium bromide (CTAB). 
     
     
         6 . The method as claimed in  claim 1 , wherein the first metal of the first metal substrate is Ag, and the second metal of the second metal substrate is Au, Pd, or Pt. 
     
     
         7 . The method as claimed in  claim 1 , wherein the weak reducing agent is a reducing agent with reducing capacity lower than that of NaBH 4 . 
     
     
         8 . The method as claimed in  claim 1 , wherein the weak reducing agent is a reducing agent with reducing capacity lower than that of sodium citrate. 
     
     
         9 . The method as claimed in  claim 7 , wherein the weak reducing agent is ascorbic acid (AA). 
     
     
         10 . The method as claimed in  claim 1 , wherein the second metal precursor is a metal salt of Ag, Pd or Pt. 
     
     
         11 . The method as claimed in  claim 10 , wherein the second metal precursor is H 2 PtCl 6 , PtS 2 O 7 H 4 , HAuCl 4 , H 2 PdCl 4 , or a combination thereof. 
     
     
         12 . The method as claimed in  claim 1 , wherein the shape of the first metal substrate is a metal nano-particle, a metal nano-wire, a metal film, a metal nano-plate, a metal foil, or a metal nano-rod. 
     
     
         13 . The method as claimed in  claim 1 , further adding a second metal precursor into the reaction solution after the first metal substrate is placed into the reaction solution for a predetermined time.