Self-Assembled Zif-67@Graphene Oxide As A Cobalt-Based Catalyst Precursor With Enhanced Catalytic Activity Toward Methanolysis Of Sodium Borohydride

In this work, a composite consisting of ZIF-67 and graphene oxide (GO) was successfully synthesized by a facile in-situ synthesis method and applied in hydrogen release from the methanolysis of sodium borohydride (NaBH4). Physicochemical properties of pure ZIF-67 and the ZIF-67@GO composites are well characterized by XRD, BET, SEM and HRTEM. It was observed that the ZIF-67 crystals are intimately anchored on GO sheets. An increase of GO in the composite led to a marked decrease of the BET surface area and an increased average pore size. However, the ZIF-67@GO precursor with high GO doping exhibited much higher activity toward the meth-anolysis of NaBH4, which suggests that the good conductivity of GO is beneficial to improve the catalytic performance. The ZIF-67@GO precursor experienced a structure reconstruction during the methanolysis reaction due to the presence of reducible Co2+. Moreover, the reduced ZIF-67@GO displayed a slightly higher activity as compared to the pristine composite and retained excellent durability after five cycles. A possible mechanism for the hydrogen generation from the methanolysis of NaBH4 using a ZIF-67@GO catalyst was proposed.