(515h) Synthesis of Graphene from Biochar

Graphene, “the wonder material” was discovered in 2004. It consists of one atom thick carbon atoms which is 100 times stronger than steel and conducts electricity. Potential applications of graphene include membranes for water purification, composites and coatings, in batteries for energy storage, microprocessors, sensors etc. Even though graphene has a huge potential, production costs limits its use. In this research, we use biochar, a solid carbon-rich material produced from biomass model compounds (cellulose, hemicellulose and lignin) produced by hydrothermal carbonization (300 ºC and 9.0 MPa), as the raw material. The biochar was further treated with 0.1 N HNO₃ to remove any soluble alkali and alkaline earth metal ions and bio-crude residues. The biochar was grinded (<0.17 mm) and uniformly distributed over copper and iron foils and heated to a temperature of 1000 ºC for 2 hours in a quartz tube with constant N₂ flow. The uniqueness of this approach is that it doesn’t require vacuum as in chemical vapor deposition to deposit graphene on metal foils. Our reactor is a simple quartz tube heated in a furnace. The role of H₂ was also studied by mixing it with the N₂ gas (1:3 vol. basis). The metal foils were analyzed by Scanning Electron Microscope (SEM), X-Ray Photoelectron spectroscopy (XPS), and Raman spectroscopy for characterizing the graphene. Graphene was observed on iron foils while no graphene growth was observed on the copper foils.