▎ 摘　　要

NOVELTY - A graphene aqueous solution is uniformly coated on a substrate to a thickness of not more than 4 mm. The substrate is dried to form a graphene film on the substrate. A reducing agent aqueous solution is prepared using sodium hydrosulfite and sodium hydroxide. The coated substrate with graphene film is soaked in the reducing agent aqueous solution and reduction process is carried out for 12-20 minutes at 50-80 degrees C. The product is washed till neutral and dried to obtain a black graphene film. USE - Preparation of graphene by chemical oxidization and reduction. ADVANTAGE - The method uses sodium hydrosulfite, which is a moderate, economical environmentally-friendly, safe, nontoxic and efficient reducing agent having high reduction efficiency and present as wide resource. DETAILED DESCRIPTION - Graphite is treated by chemical oxidization to obtain water-soluble oxidized graphene. Graphene is added to water in a concentration of 1-6 mg/ml and vibrated or stirred at normal temperature to uniformly disperse graphene in water and obtain oxidized graphene aqueous solution. The solution is uniformly coated on a substrate by spin coating method or pouring method, controlling the coating thickness to not more than 4 mm. The substrate is dried in vacuum at 80 degrees C or less to form a graphene film on the substrate. A reducing agent aqueous solution is prepared using sodium hydrosulfite and sodium hydroxide in a mass ratio of 1:2-1:6. The concentration of aqueous solution is 2-10% based on sodium hydroxide. The coated substrate with graphene film is soaked in the reducing agent aqueous solution and reduction process is carried out for 12-20 minutes at 50-80 degrees C. The product is washed till neutral and dried to obtain a black graphene film.