Metal-Organic Framework-Derived FeCo2S4/Co3O4 Heterostructure with Enhanced Electrocatalytic Performance for Oxygen Evolution and Hydrogen Evolution Reactions

Herein, a versatile FeCo2S4/Co3O4 heterostructure consisting of zeolitic imidazolateframework ZIF-derived Co3O4 and FeCo-layereddouble hydroxide-derived Fe-doped Co sulfide is employed for the all-importantalkaline full water splitting process. The heterostructure is preparedby combining pyrolysis and hydrothermal/solvothermal processes. Thesynthesized heterostructure possesses an electrocatalytically richinterface and renders excellent bifunctional catalytic performance.An overpotential of 139 mV for a standard cathodic current of 10 mAcm(-2) with a low Tafel slope of 81 mV dec(-1) is recorded for the hydrogen evolution reaction. An overpotentialof 210 mV is observed for an anodic current of 20 mA cm(-2) with a low Tafel slope of 75 mV dec(-1) recordedfor the oxygen evolution reaction. The full-symmetric two-electrodecell was capable of generating a current density of 10 mA cm(-2) at a cell potential of 1.53 V and a low onset potential of 1.49V. The symmetric cell architecture exhibits remarkable stability,as a negligible potential increase is observed for continuous watersplitting over a 10 h period. With the reported performance, the heterostructurecompares well with most of the excellent reported catalysts for alkalinebifunctional catalysts.