Designing a bimetallic transition metal oxide/hydroxide composite for effective electrocatalytic oxygen evolution reaction

Highlights: • A ZnO/Ni(OH)₂ composite was synthesized through PVP-DA assisted hydrothermal method. • The overpotential of 170 mV was obtained for OER at 10 mA cm⁻² current density. • Surface roughness and synergism within metal centers improved catalytic behavior. • DFT calculations were performed to understand the reaction mechanism. The oxygen evolution reaction (OER), owing to its sluggish nature, demands efficient and stable catalysts with low production cost, during the electrocatalytic water splitting. In this respect, a series of bimetallic ZnO-Ni(OH)₂ composite materials were prepared as electrode materials for OER. The synthetic procedure followed the polyvinylpyrrolidone (PVP) and dopamine (DA) assisted hydrothermal process. The growth modification ability of PVP and adhesive property of polydopamine (from DA) were utilized to attain the 3D interconnected structures. The precursor concentrations were varied to obtain most efficient catalyst, ZNDP-1. In alkaline medium, ZNDP-1 showed a low over potential of 170 mV (@10 mAcm⁻² current density) and a Tafel slope of 61 mV dec⁻¹ with significant stability. The surface defects, porosity and synergism within metal centers might cause efficient electrocatalytic activity. Furthermore, DFT studies were performed to understand the mechanistic pathway.