In situ self-assembled 3-D interconnected pristine graphene supported NiO nanosheets as superior catalysts for oxygen evolution

Supported nanostructures of oxygen evolution catalysts with three-dimensional (3-D) architectures are promising for significantly boosting the oxygen evolution reaction (OER) efficiency, but are difficult to fabricate. We report the synthesis of 3-D interconnected pristine graphene supported NiO nanosheets via in situ self-assembly. Its overpotential at 10 mA cm⁻² is 320 mV and Tafel slope is 52.4 mV dec⁻¹, both of which are lower than most reported values of NiO-based catalysts and even Ir and Ru-based ones. It exhibits only a slight loss of the current density after 20 h of chronoamperometric measurement at an overpotential of 320 mV (from 10.09 to 9.62 mA cm⁻²) and a small increase after 1000 CV cycles (from 41.47 to 46.01 mA cm⁻² at 1.58 V). The synthesis of NiO nanosheets on graphene offers key insights into the self-assembly mechanism. The reported in situ self-assembly of metal oxide nanostructures with 3-D architecture on graphene is a low-cost, facile and mild strategy for making high-performance OER catalyst demonstrating the advantages of 3-D interconnected nanostructures supported on graphene.