Preparation And Properties Of MgAl Double Hydroxide And Coni Hydroxide Based On Graphene

Graphene is applied in catalyst carrier and energy storage,exhibits excellent performance and broad application prospect,therefore,recently graphene composite as important application field of graphene are attracted extensively attentions.MgAl double metal hydroxide(LDH)/graphene oxide composite was prepared and used as solid base catalyst for aldol condensation reaction.CoNi hydroxide/reduced graphene oxide composite was synthesized and used as super capacitor electrode materials.(a)Graphite oxide with single or double atomic thin layers was prepared by Hammer method.MgAl-LDH crystal plates were in situ grown on graphene oxide by coprecipitation method.Activated MgAl-LDH/reduced graphene oxide(R-MgAl-LDH/rGO)was obtained by using calcinations and activation and recovery of hydration,and used as solid base catalyst for self-condensation reaction of acetone.Results show that the high specific surface area of graphene oxide carrier is favorable to dispersion and full exposure of active sites on MgAl-LDH crystal plates,and the strong interaction between supporter and layered MgAl-LDH can effectively improve the structure stability of the as-prepared catalyst and raise the electron transfer rate in the process of catalytic reaction,therefore,activated MgAl-LDH/reduced graphene oxide exhibits better catalytic properties for self-condensation reaction of acetone compared to pure MgAl-LDH.Results show that when the Mg/Al ratio was 3,GO was 0.2 g,the catalytical activity got the highest,the reaction reached equilibrium after about 245 min,the selectivity of DAA nearly 100%.(b)Polyaniline was grown on surface of graphene oxide by in situ polymerization.The resulting polyaniline modified grapheme oxide(GP)was used as matrix material,CoNi hydroxide was in situ grown on GP by ammonia coprecipitation method,resulting in the formation of CoNi hydroxide/polyaniline modified graphene oxide composite(GPCoNi).Three electrode system was adopted to investigate capacitance property.Results show that the current density was 1 A/g,capacitance reached 2757 F/g,after charge-discharge cycles were 1000 times,the capacitance retention rate was 93.2%,presenting better stability.To investigate practical property of GPCoNi,a super capacitor was assembled,in which GPCoNiwas used as anode material,activated carbon as cathode,polyethylene as solid electrolyte and nickel foam as current collector.Results show that when the current density was 0.5 A/g,specific capacitance of GPCoNi reached 239.81 F/g.