▎ 摘　　要

NOVELTY - The method for preparing graphene heterojunction, involves (i) using graphene oxide as a solute and ethanol as solvent, and preparing graphene oxide ethanol solution, ultrasonically processing, centrifuging, taking the supernatant, and obtaining graphene oxide grafting liquid, (ii) spreading prepared graphene oxide grafting liquid on sub-phase, evaporating solvent, forming loose graphene oxide nanosheets surface, sliding two sliding barriers, compressing area of liquid surface of graphene oxide nanosheets, and forming graphene oxide film surface. USE - Method for preparing graphene heterojunction (claimed). ADVANTAGE - The method simplifies the preparation process, reduces the cost, prepares graphene heterojunction with controllable number of layers of graphene oxide. The size of the heterojunction can be adjusted according to the substrate. The preparation process is environmentally-friendly. DETAILED DESCRIPTION - The method for preparing graphene heterojunction, involves (i) using graphene oxide as a solute and ethanol as solvent, and preparing graphene oxide ethanol solution with concentration of 0.1-0.3 mg/mL, ultrasonically processing the solution for 5-10 minutes, centrifuging at a speed of 3500-6500 rpm for 10-15 minutes, taking the supernatant, and obtaining graphene oxide grafting liquid, (ii) spreading prepared graphene oxide grafting liquid on sub-phase with a syringe, evaporating solvent, forming loose graphene oxide nanosheets surface, sliding two sliding barriers, compressing area of liquid surface of graphene oxide nanosheets, and compressing tightly loose nanosheets, and forming graphene oxide film surface where the sub-phase is deionized water, the speed of sliding barrier compression liquid surface is 5-20 mN/m/minute, (iii) slowly immersing substrate into surface of graphene oxide film in a direction of vertical liquid surface by an immersion coating machine and then slowly drawing so that graphene oxide film is transferred onto the substrate to obtain a single layer of graphene oxide film, (iv) placing the obtained monolayer graphene oxide film in a closed container, placing a hydrazine hydrate solution capable of immersing the substrate in a concentration of 98% in a container for 8-12 minutes to obtain a reduced graphene oxide film, (v) using the sample reduced in step (iv) as a substrate, slowly immersing substrate in a direction perpendicular to a liquid surface of graphene oxide film by a dip coating machine and slowly pulling up to transfer graphene oxide film on the substrate, and obtaining reduced graphene oxide-graphene oxide which is graphene heterojunction.