Atomic Heterointerface Engineering of Nickel Selenide Confined Nickel Molybdenum Nitride for High-Performance Solar-Driven Water Splitting

A heterostructured electrocatalyst of small NiSe₂ nanoparticles confined NiMoN nanorods (NiSe₂–NPs/NiMoN–NRs) is prepared to accelerate both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in a same alkaline medium. The synergistic effects caused by the combination of merits derived from NiSe₂ and NiMoN phases trigger an optimum electronic structure with high density of state at near Fermi level and enhance adsorption free energy, thereby resulting in excellent catalytic activities and strengthened working stability. The catalyst requires a low overpotential of 58 mV for HER and 241 mV for OER to reach 10 mA cm⁻² in 1.0 M KOH electrolyte. A two-electrode electrolyzer based on the developed catalyst shows outstanding cell voltage of 1.51 and 1.46 V to reach 10 mA cm⁻² in 1.0 M and 30 wt% KOH solution at 25 °C for overall water splitting, respectively. In addition, the solar-driven water splitting process delivers a high solar-to-H₂ conversion efficiency of ∼18.4%, impressively unveiling that the developed bifunctional catalyst is highly potential for overall water splitting to produce green hydrogen fuel.