Method of making a transparent conductive composite material

Abstract

A method of making a transparent conductive material includes: preparing a reactive solution that contains a solvent, a metal salt which is dissolved in the solvent, and a powder of graphene oxide which is dispersed in the solvent; and simultaneously reducing metal ions of the metal salt and the graphene oxide in the reactive solution to form a plurality of core-shell nanowires, each of which includes a core of a metal reduced from the metal ions, and a shell of graphene surrounding the core.

What is claimed is: 
     
         1 . A method of making a transparent conductive material, comprising:
 preparing a reactive solution that contains a first solvent, a metal salt which is dissolved in the first solvent, and a powder of graphene oxide which is dispersed in the first solvent; and   simultaneously reducing metal ions of the metal salt and the graphene oxide in the reactive solution to form a plurality of core-shell nanowires, each of which includes a core of a metal reduced from the metal ions, and a shell of graphene surrounding the core.   
     
     
         2 . The method of  claim 1 , wherein the first solvent is a reducing agent that is reactive with the metal ions and the graphene oxide for reducing the metal ions and the graphene oxide. 
     
     
         3 . The method of  claim 2 , wherein the first solvent is polyhydroxy alcohol. 
     
     
         4 . The method of  claim 3 , wherein the polyhydroxy alcohol is selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, glycerin, and combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the metal salt is selected from the group consisting of silver nitrate, silver perchlorate, and silver fluoride. 
     
     
         6 . The method of  claim 1 , wherein the reactive solution is heated to a temperature not smaller than 150° C. during simultaneous reduction of the metal ions and the graphene oxide. 
     
     
         7 . The method of  claim 1 , wherein the reactive solution further contains a templating reagent that is selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, poly(dimethylsiloxane), poly(oxyethylene), and combinations thereof. 
     
     
         8 . The method of  claim 1 , wherein the reactive solution further contains a buffer agent that is selected from the group consisting of a metal halide, a metal sulfide, and a metal nitrate. 
     
     
         9 . The method of  claim 8 , wherein the metal halide is silver bromide or silver chloride. 
     
     
         10 . The method of  claim 1 , wherein the preparation of the reactive solution is conducted by adding a graphene oxide-containing solution that contains the graphene oxide into a precursor solution that contains the metal salt and the first solvent while maintaining the precursor solution at an elevated temperature not smaller than 150V. 
     
     
         11 . The method of  claim 10 , further comprising reducing a portion of the metal ions in the precursor solution under the elevated temperature to form a plurality of nanowire seeds prior to the addition of the graphene oxide-containing solution into the precursor solution. 
     
     
         12 . The method of  claim 11 , wherein the graphene oxide-containing solution is prepared by adding the powder of graphene oxide into a second solvent to result in a mixture, followed by subjecting the mixture to ultrasonication to disperse and exfoliate the powder of graphene oxide in the second solvent, and wherein the second solvent is miscible with the first solvent. 
     
     
         13 . The method of  claim 12 , wherein the second solvent is selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, glycerin, and combinations thereof. 
     
     
         14 . A transparent conductive material comprising a plurality of core-shell nanowires and a plurality of nanowebs of graphene, said core-shell nanowires randomly crossing one another, each of said core-shell nanowires including a core of a metal and a shell of graphene surrounding the core, said nanowebs randomly extending from said shells of said core-shell nanowires to interconnect said core-shell nanowires to form a network structure. 
     
     
         15 . The transparent conductive material of  claim 14 , wherein said metal is silver. 
     
     
         16 . The transparent conductive material of  claim 14 , wherein said graphene is p-type doped reduced graphene. 
     
     
         17 . The transparent conductive material of  claim 14 , wherein said graphene is doped with halide ions.