▎ 摘　　要

NOVELTY - Preparing three-dimensional graphene for detecting dopamine electrochemically involves preparing three-dimensional graphene material involves preparing ultrafine nickel powder by hydrazine reduction method, adding 0.8-1.6 mol of hydrazine hydrate (N2H4 H2O) into a solution of 0.2-0.4 mol of Nickel(II) chloride hexahydrate (NiCl2 6H2O), where the solution changes from green to light purple, the temperature of the solution rises to 60 degrees C, carrying out the reaction in a water bath heated at 50 degrees C, placing the water bath on a magnetic stirrer at 100-300 revolutions/minute, where the mass fraction of hydrazine hydrate (N2H4 H2O) is 80%, using a small amount of deionized water to wash away the light purple adhesive remaining on the beaker wall, adding 0.8-1.6 mol of sodium hydroxide (NaOH) solution after the temperature drops to 50 degrees C, where the solution turns pale green, as the reaction time increased, the solution gradually darkened, reacting for 4 hours. USE - Method for preparing three-dimensional graphene/ITO, which is used as a working electrode of a biosensor to detect dopamine electrochemically (claimed). ADVANTAGE - The method enables to prepare three-dimensional graphene material, which has large specific surface area, high electrical conductivity and good biocompatibility. DETAILED DESCRIPTION - A black precipitate is appeared at the bottom of the solution, and the upper layer is a clear solution, where the mass fraction of sodium hydroxide (NaOH) is 50%, washing the black precipitate with deionized water and ethanol, respectively, performing suction filtration, performing vacuum drying at 50-90 degrees C for 1-2 hours to obtain ultra-fine nickel powder, performing chemical vapor deposition to prepare three-dimensional graphene, loosing ultra-fine nickel powder filled with ceramic container, placing in the center of quartz tube furnace, heating from room temperature at a heating rate of 10-20 degrees C/minute to 800-950 degrees C under the protection of argon and hydrogen, maintaining the temperature at 800-950 degrees C for 20-40 minutes, sintering the loose ultra-fine nickel powder together to form a three-dimensional nickel template, introducing methane gas into the tube furnace at 800-950 degrees C for 10-30 minutes at a flow rate of 10-20 standard cubic centimeters per minute (sccm), cooling the quartz tube furnace from room temperature to 800-950 degrees C to room temperature at a cooling rate of 120-160 degrees C/minute, coating the surface of the three-dimensional nickel template with multiple layers of graphene, where the ceramic container is composed of a ceramic plate and a ceramic ring, where the outer diameter of the ceramic ring is 26.3 mm, the inner diameter is 18.2 mm, and the thickness is 3 mm, where the ultrafine nickel powder is 200-500 nanometer (nm) in diameter, the flow rate of the argon gas is 400-500 sccm, the flow rate of the hydrogen gas is 180-220 sccm, dissolving polymethyl methacrylate in ethyl lactate, heating and stirring at 80-120 degrees C for 1.5-2.5 hours to obtain a mixed solution, using a pipetting gun, adding the mixed solution dropwise to the graphene-encapsulated three-dimensional nickel template, where the temperature is maintained at 180-200 degrees C for 1-2 hours, coating the surface of the three-dimensional graphene with a layer of polymethyl methacrylate, where the mass fraction of methyl methacrylate in the mixed solution is 4-5%, immersing completely the three-dimensional graphene coated with polymethyl methacrylate obtained in a hydrochloric acid solution having a temperature of 60-80 degrees C and a concentration of 2-3 mol/Litre for 8-15 hours, removing three-dimensional graphene from nickel, immersing the nickel-removed three-dimensional graphene in acetone at 50-60 degrees C for 3-5 hours, obtaining the three-dimensional graphene by removing polymethyl methacrylate, cleaning the obtained three-dimensional graphene with deionized water, transferring the cleaned polymethyl methacrylate-removed three-dimensional graphene to clean indium tin oxide (ITO) glass and freeze-drying for 0.5-1 hour to obtain a three-dimensional graphene/ITO electrode.