Precisely manipulating the d-band center of Ni_1-xCo_xMoO₄·nH₂O for enhanced alkaline oxygen evolution with low overpotential

Electrocatalytic water splitting has long been limited by the sluggish kinetics of the anodic oxygen evolution reaction (OER). Replacing RuO₂ and IrO₂ with efficient, non-noble metal catalysts for the OER is crucial for advancing large-scale hydrogen production via water electrolysis. Leveraging the interactions between metal cations, the binary transition metal oxide NiMoO₄ exhibits significant potential for the OER activity. In this study, we present an effective Co-doping strategy that adjusts the d-band center of Ni sites in NiMoO₄, optimizing the adsorption energy of OER intermediates and lowering the energy barrier for the reaction. As a result, the Ni_0.8Co_0.2MoO₄·nH₂O electrode catalyst achieves an ultra-low overpotential of 270 mV at a high current density of 100 mA cm^-2, along with outstanding long-term stability for OER in 1 M KOH over 50 h, outperforming the benchmark RuO₂ catalyst.