Oxygen vacancy enriched NiMoO4 nanorods via microwave heating: a promising highly stable electrocatalyst for total water splitting

Abstract

It is indeed necessary to develop a suitable bi-functional catalyst for total water splitting. Here, in this work, we demonstrate a microwave-assisted formulation of NiMoO₄ nanorods within 30 minutes of the reaction time. As synthesized NiMoO₄ nanorods grown on nickel foam were treated with NaBH₄ to create internal oxygen vacancies [NiMoO₄(V_o)] that favoured OER and HER with very merginal applied overpotential. The generation of oxygen vacancies in the lattice generally leads to the formation of an effective electronic structure for proceeding OER activity in a sustainable way. When vacancy-enriched NiMoO₄(V_o) nanorods were applied for OER and HER under alkaline conditions, it demands only 220 and 255 mV overpotential at 50 mA cm⁻² current density, respectively. Having observed their phenomenal response in both OER and HER, they were analysed for the real device as the two-electrode system (NiMoO₄(V_o) nanorods as anode and cathode); they needed 490 mV as overpotential at 50 mA cm⁻². Based on the molecular orbital and band-structured theories, it has been understood that the band gap state (BGS) led to the formation of antibonding states with a very low electron population that favoured rich OER and HER kinetics, as observed from the electrochemical results.