Lignin based laser lithography process for fabricating 3d graphene electrode and method

Abstract

There is a method for forming a three dimensional or porous graphene electrode pattern on a substrate, the method including providing a substrate; coating the substrate with a lignin-polymer composite film; exposing a first part of the coated lignin-polymer composite film to a laser beam for transforming the first part into the graphene pattern; and removing a second part of the coated lignin-polymer composite film, which was not exposed to the laser beam, by placing the second part in water. The lignin-polymer composite film includes (1) a water-soluble alkaline lignin, (2) a polymer having bonding properties, and (3) a solvent, and an amount of the water-soluble alkaline lignin in the lignin-polymer composite film is between 5 and 60% by weight.

What is claimed is: 
     
         1 . An electrode comprising:
 a substrate;   a lignin-polymer composite film coating the substrate; and   a metallic layer coating the lignin-polymer composite film,   wherein a first part of the coated lignin-polymer composite film has been exposed to a laser beam that transformed the first part into a graphene pattern,   wherein a second part of the coated lignin-polymer composite film, which was not exposed to the laser beam, is removed by placing the second part in water, and wherein the lignin-polymer composite film includes (1) a water-soluble alkaline lignin, (2) a polymer having bonding properties, and (3) a solvent, and an amount of the water-soluble alkaline lignin in the lignin-polymer composite film is between 5 and 60% by weight.   
     
     
         2 . The electrode of  claim 1 , wherein the graphene pattern is shaped as in-plane interdigitated electrodes. 
     
     
         3 . The electrode of  claim 2 , wherein the in-plane interdigitated electrodes are part of a supercapacitor. 
     
     
         4 . The electrode of  claim 1 , wherein the metallic layer includes gold to increase a conductivity of the electrode. 
     
     
         5 . The electrode of  claim 1 , further comprising:
 a transistor located over the first part.   
     
     
         6 . The electrode of  claim 1 , wherein the solvent is water and the polymer having bonding properties is Poly(vinyl) alcohol (PVA). 
     
     
         7 . The electrode of  claim 1 , wherein the lignin-polymer composite film includes (1) 10% by weight of the water-soluble alkaline lignin, (2) 10% by weight of the polymer having bonding properties, and (3) 80% by weight of the solvent. 
     
     
         8 . The electrode of  claim 1 , wherein the water-soluble alkaline lignin includes sulphur.