Reduced Graphene Oxide Sheets Supported Waxberry-like Co Catalysts for Improved Hydrolytic Dehydrogenation of Ammonia Borane

摘要

Cobalt nanoparticles(NPs)supported on reduced graphene oxide sheets have been synthesized via a facile chemical reduction method by adding surfactant PVA and controlling the preparation process.Compared with regular Co NPs and unsupported waxberry-like Co NPs,the synthesized Co@rGO exhibited waxberry-like structure and amorphous state,good dispersion,uniform particle size with 25 nm.The waxberry-like Co@rGO catalyst needed 10.8 min for hydrolytic dehydrogenation of NH3·BH3,with an initial turnover frequency(TOF)of 12.14 mol_(H2)·min~(-1)·mol_(Co)~(-1)and the activation energy of 45.49 kJ·mol~(-1).The improved catalytic activity can be ascribed to the special morphology and decreased particle size of Co NPs,as well as the synergistic effect between graphene sheets and Co NPs.The work also includes the kinetic studies on zero-order with respect to substrate concentration and first-order reaction with respect to catalyst concentration.