Method for continuous production of high quality graphene

Abstract

A continuous method for manufacturing graphene films using a metal substrate, wherein a first surface of the metal substrate is heated such that a top layer of the first surface melts to form a molten metal layer, and devices for carrying out the same.

What is claimed is: 
     
         1 . A continuous method for preparing a film comprising graphene, the method comprising:
 providing a metal substrate;   continuously advancing the metal substrate into and through a processing chamber;   heating the metal substrate to form a molten metal layer on a top surface of the metal substrate;   contacting the molten metal layer with a carbon source gas to form a graphene-comprising layer substantially covering the molten metal layer of the top surface of the metal substrate;   solidifying the molten metal layer;   advancing the metal substrate having the graphene-comprising layer out of the processing chamber to form a film comprising graphene.   
     
     
         2 . The method of  claim 1 , wherein the metal substrate comprises a metal foil or a metal film having a metal selected from the group consisting of copper, nickel, ruthenium, rhodium, aluminum, and alloys thereof. 
     
     
         3 . The method according to  claim 2 , wherein the metal foil or metal film is provided with a second substrate comprising a metalloid and/or an oxide thereof. 
     
     
         4 . The method according to  claim 3 , wherein the metalloid and/or oxide thereof is selected from the group consisting of Si, SiO 2 , and combinations thereof. 
     
     
         5 . The method according to  claim 1 , wherein an atmosphere of the processing chamber is between about 10 −8  atm and 100 atm 
     
     
         6 . The method according to  claim 1 , wherein contacting the molten metal layer with the carbon source gas further comprises contacting the molten metal layer with a secondary gas, the secondary gas being selected from the group consisting of argon, helium, nitrogen, hydrogen, and mixtures thereof. 
     
     
         7 . The method according to  claim 6 , wherein the carbon source gas comprises methane and the secondary gas comprises nitrogen, argon, and hydrogen. 
     
     
         8 . The method according to  claim 7 , wherein a flow rate ratio of nitrogen to argon to hydrogen to methane into the processing chamber is about 20:60:40:1. 
     
     
         9 . The method according to  claim 1 , wherein a thickness of the molten metal layer is such that a solutal Marangoni number for the metal substrate having the molten metal layer on the top surface thereof is lower than 80, wherein the solutal Marangoni number is: 
       
         
           
             
               
                 M 
                 a 
                 s 
               
               = 
               
                 
                   
                     γ 
                     c 
                   
                    
                   d 
                    
                   
                       
                   
                    
                   Δ 
                    
                   
                       
                   
                    
                   c 
                 
                 
                   μ 
                    
                   
                       
                   
                    
                   
                     D 
                     L 
                   
                 
               
             
           
         
         wherein: 
         γ c  is a solutal surface tension coefficient, 
         Δc is a concentration gradient across a melt, 
         d is the thickness of the molten metal layer, 
         D L  is molecular diffusivity in liquid, and 
         μ is dynamic viscosity. 
       
     
     
         10 . A film comprising graphene prepared by a method comprising:
 providing a metal substrate;   continuously advancing the metal substrate into and through a processing chamber comprising one or more heating elements and one or more gas supply components;   heating the metal substrate to form a molten metal layer on a top surface of the metal substrate;   contacting the molten metal layer with a carbon source gas to form a graphene-comprising layer substantially covering the molten metal layer of the top surface of the metal substrate;   solidifying the molten metal layer;   advancing the metal substrate having the graphene-comprising layer out of the processing chamber; and   separating the graphene-comprising layer to form a film comprising graphene.   
     
     
         11 . The film of  claim 10 , wherein the metal substrate comprises a metal foil or a metal film. 
     
     
         12 . The film of  claim 10 , wherein the processing chamber comprises:
 a preheating zone comprising the one or more heating elements,   a processing zone comprising the one or more gas supply components, and   a cooling zone,   wherein the molten metal layer is formed as the metal substrate advances through the preheating zone, the molten metal layer is contacted with the carbon source gas in the processing zone, and the molten metal layer is solidified in the cooling zone.   
     
     
         13 . The film of  claim 10 , wherein the metal substrate is advanced from an unwinding roll into the processing chamber. 
     
     
         14 . The film of  claim 10 , wherein the metal substrate having the graphene-comprising layer is wound onto a winding roll after it has been advanced out of the processing chamber. 
     
     
         15 . The film of  claim 10 , wherein the one or more heating elements comprises at least two heating elements. 
     
     
         16 . The film of  claim 15 , wherein the at least two heating elements comprises a first heating element which heats the top surface of the metal substrate and a second heating element which heats a bottom surface of the metal substrate. 
     
     
         17 . The film of  claim 16 , wherein the first heating element heats the top surface of the metal substrate to no more than about 50° C. different than a melting point of the top surface of the metal substrate. 
     
     
         18 . The film of  claim 17 , wherein the first heating element heats the top surface of the metal substrate to a temperature of about 1050° C.±30° C. 
     
     
         19 . The film of  claim 16 , wherein the second heating element heats the bottom surface of the metal substrate to a temperature that is below a melting point of the bottom surface of the metal substrate. 
     
     
         20 . The film of  claim 19 , wherein the second heating element heats the bottom surface of the metal substrate to a temperature that is below about 1050° C.