Facile synthesis of hollow Co3O4-embedded carbon/reduced graphene oxides nanocomposites for use as efficient electrocatalysts in oxygen evolution reaction

Abstract The development of non-noble-metal electrocatalysts that are both efficient and stable is of upmost important for the oxygen evolution reaction (OER) in renewable-energy technologies. In this study, cobalt-based zeolitic imidazolate frameworks wrapped by graphene oxide-water (denoted as ZIF-67/GO-W) were successfully prepared by a simple precipitate reaction using water as solvent. Due to the high dispersion of GO in aqueous solution, the synthesis of ZIF-67/GO-W enabled a smaller particle size of ZIF-67 to be attained, also resulted in a more homogeneous distribution between ZIF-67 and GO. Furthermore, a novel hybrid nanostructure comprised of hollow Co 3 O 4 -embedded carbon/reduced graphene oxides (Co 3 O 4 C/rGO-W) is achieved through a facile synthetic route involving the calcination-oxidation of ZIF-67/GO-W. The resulting nanocomposites were found to combine the high conductivity of graphene, the promising catalytic properties of the hollow Co 3 O 4 nanoparticles and a homogeneous distribution of the ZIF-67/GO-W precursor. Enhanced OER activity and improved stability was therefore realized. The hollow Co 3 O 4 C/rGO-W was found to exhibit a low overpotential (382 mV) and a low tafel slope (62 mV dec −1 ) in 0.1 M KOH, rendering them comparable to the commercial RuO 2 catalyst and an improvement to Co 3 O 4 nanoparticles. This work presents an alternative strategy for the development of uniformly distributed ZIF-67/GO-W using water as solvent and suggests hollow Co 3 O 4 C/rGO-W as potential electrocatalysts for the OER in energy-related applications.