▎ 摘　　要

NOVELTY - Preparing copper oxide-doped ultra-thin nickel-iron-based hydrotalcite nanoflake / graphene bifunctional water decomposition catalyst involves performing co-precipitation method in a formamide-water mixed solution containing graphene oxide, where dispersing a certain amount of graphene oxide (GO) in 100 mL of a mixed solvent of formamide and water to a concentration of 0.3 mg/mL. The iron nitrate nonahydrate, nickel nitrate hexahydrate, and copper nitrate hexahydrate are added at a certain molar ratio, so that the total metal ion concentration of nickel iron is 0.03 mol/L. The molar concentration of copper metal ions is 1-5 wt.% of the total molar concentration of nickel iron metal ions, and stirred for 1 hour to completely dissolve the metal salt. The solution is titrate slowly with a 0.7 mol/L formamide-containing sodium hydroxide aqueous solution until the pH of the reaction solution is 8.5-9.5, and add 100 microliter of 80 wt.% hydrazine hydrate to the mixture. USE - Method for preparing copper oxide-doped ultra-thin nickel-iron-based hydrotalcite nanoflake / graphene bifunctional water decomposition catalyst used for oxygen evolution reaction and hydrogen evolution reaction of electrolytic water in an alkaline medium (claimed). ADVANTAGE - The method enables to prepare copper oxide-doped ultra-thin nickel-iron-based hydrotalcite nanoflake / graphene bifunctional water decomposition catalyst, that avoids steps such as peeling of hydrotalcite and doping after copper oxide, suppresses the aggregation of graphene, copper oxide and hydrotalcite-like nanosheets, increases the active site, and improves the conductivity, and obtained catalyst reduces the mass transfer resistance, accelerates the electron transfer rate, improves the catalytic performance of oxygen evolution and hydrogen evolution under alkaline conditions, and provides an important method for the development of new bifunctional water decomposition catalysts. DETAILED DESCRIPTION - Preparing copper oxide-doped ultra-thin nickel-iron-based hydrotalcite nanoflake / graphene bifunctional water decomposition catalyst involves performing co-precipitation method in a formamide-water mixed solution containing graphene oxide, where dispersing a certain amount of graphene oxide (GO) in 100 mL of a mixed solvent of formamide and water to a concentration of 0.3 mg/mL. The iron nitrate nonahydrate, nickel nitrate hexahydrate, and copper nitrate hexahydrate are added at a certain molar ratio, so that the total metal ion concentration of nickel iron is 0.03 mol/L. The molar concentration of copper metal ions is 1-5 wt.% of the total molar concentration of nickel iron metal ions, and stirred for 1 hour to completely dissolve the metal salt. The solution is titrate slowly with a 0.7 mol/L formamide-containing sodium hydroxide aqueous solution until the pH of the reaction solution is 8.5-9.5, and add 100 microliter of 80 wt.% hydrazine hydrate to the mixture. It is gradually heated to 100 degrees C for 2 hours. After cooling, the reaction solution is centrifuged, and the precipitate was washed 3 times with deionized water and ethanol. After drying, copper oxide-doped ultra-thin nickel-iron-type hydrotalcite nanosheets / graphene composites (CuO-NiFe-LDHNS / rGO) are obtained. The molar ratio of iron nitrate nonahydrate and nickel nitrate hexahydrate is 1:2. The volume percentage of formamide in a mixed solvent or solution of formamide and water is 40-100 vol.%. The size of the hydrotalcite nanosheets (LDHNS) in the obtained CuO-NiFe-LDHNS / rGO composite catalyst is 20-50 nanometer, and the thickness is less than 3 nanometer. The copper oxide (CuO) has a particle size of 3-15 nanometer and is uniformly doped in the LHDNS matrix.