▎ 摘　　要

NOVELTY - A nitrogen-doped graphene/cobalt iron-based hydrotalcite bifunctional oxygen catalyst is prepared by calcining cobalt-iron-containing hydrotalcite (LDH) at high temperature into cobalt iron bimetallic oxide (CoFe-LDO), assembling graphene oxide (GO) on cobalt-hydrotalcite-like sheet, forming oxidized graphene/cobalt-iron-based hydrotalcite complex, doping carbon nitride nanoplate in presence of hydrazine hydrate, and forming nitrogen-doped graphene (NG)/cobalt-iron-like hydrotalcite-like nanocomposite. USE - Nitrogen-doped graphene/cobalt iron-based hydrotalcite bifunctional oxygen catalyst is used for alkaline electrolysis and oxygen reduction of fuel cells. ADVANTAGE - The nitrogen-doped graphene/cobalt iron-based hydrotalcite bifunctional oxygen catalyst has excellent catalytic activity and methanol resistance, and is prepared economically by simple method with high productivity. DETAILED DESCRIPTION - A nitrogen-doped graphene/cobalt iron-based hydrotalcite bifunctional oxygen catalyst is prepared by calcining cobalt-iron-containing hydrotalcite (LDH) at high temperature into cobalt iron bimetallic oxide (CoFe-LDO), assembling graphene oxide (GO) on cobalt-hydrotalcite-like sheet, forming oxidized graphene/cobalt-iron-based hydrotalcite complex, doping carbon nitride nanoplate in presence of hydrazine hydrate, and forming nitrogen-doped graphene (NG)/cobalt-iron-like hydrotalcite-like nanocomposite. The cobalt iron bimetallic oxide hybrid is obtained by dissolving cobalt chloride hexahydrate and ferric chloride hexahydrate in ultrapure water at preset ratio so that total metal ion concentration is 0.215 mol/L, stirring to dissolve completely, dripping 1.5 mol/L sodium hydroxide at constant rate until the pH of 8, transferring mixture to the reaction vessel, reacted at 130 degrees C for 24 hours, centrifugally-separating, washing using deionized water and ethanol, and dry-grinding in air atmosphere at 500 degrees C for 5 hours. GO/LDH complex is obtained by adding preset amount of graphite oxide in ultrapure water, ultrasonically dispersing for 4 hours, centrifuging at 5000 rpm for 10 minutes, removing un-stripped graphite oxide, obtaining 1-6 mg/mL solution, gradually adding 50 mg CoFe-LDO hybrid under stirring, stirring at room temperature for 12 hours, and centrifuging at 3000 rpm for 10 minutes. NG/LDH catalyst is obtained by adding 0.5 g graphite-phase nitrided carbon, dissolving in 14 mL concentrated sulfuric acid solution, stirring at room temperature for 2 hours, adding 50 mL deionized water, ultrasonically processing for 2 hours, washing to neutral, obtaining aqueous dispersion of 0.3-0.7 mg/m nanoplate, adding preset amount GO/LDH complex, ultrasonically processing, adding 2 mL hydrazine hydrate, stirring at 180 degrees C for 20 hours, centrifuging solid sample, washing using deionized water and ethanol and drying.