Heterostructured Co3O4/CoWO4 architecture modified by 2-D reduced graphene oxide for enhanced overall water splitting

Abstract

Cobalt-based materials emerge as highly efficient non-noble metal catalysts for electrochemical alkaline water splitting. Their performance depends on morphology, chemical composition, and structural attributes, which require optimization to enhance charge transfer. In this study, we report a composite heterostructured architecture comprising Co3O4 and CoWO4 integrated with reduced graphene oxide (rGO) for overall alkaline water splitting. The incorporation of the mesoporous CoWO4 − rGO composite with Co3O4 enhances charge and mass transport, thereby improving catalytic performance. The Co3O4/CoWO4 − rGO heterostructure demonstrates excellent electrocatalytic activity, delivering low overpotentials of 240 mV for the oxygen evolution reaction and 195 mV for the hydrogen evolution reaction at a current density of 50 mA cm−2. The Co3O4/CoWO4 − rGO heterostructure, when used as a bifunctional electrode for overall alkaline water splitting, delivers a current density of 50 mA cm−2 at a cell potential of 1.55 V and remains stable for more than 100 h. The findings demonstrate that surface-engineered Co3O4/CoWO4 − rGO heterostructures exhibit significant promise as durable and high performance electrocatalysts for sustainable alkaline water splitting.