Precisely engineering the electronic structure of active sites boosts the activity of iron-nickel selenide on nickel foam for highly efficient and stable overall water splitting

The development of efficient and stable electrocatalysts to speed up the sluggish kinetics of water splitting has long been being the frontier of energy conversion research. Herein, we report a highly efficient electrocatalyst of P-Ni0.75Fe0.25Se2 prepared on nickel foam for overall water splitting. The optimal P-Ni0.75Fe0.25Se2 electrode exhibits an extremely low overpotential of 156 mV at 10 mA cm−2 and 226 mV at 300 mA cm−2 for oxygen evolution reaction (OER) and the highly efficient activity remains stable for up to 1000 h at 300 mA cm−2. More importantly, the water-alkali electrolyzer of P-Ni0.75Fe0.25Se2 || MoNi4/MoO2 requires only 1.45 V and 1.82 V to reach current densities of 10 and 300 mA cm−2, respectively, outperforming that of RuO2 || MoNi4/MoO2. Systematically theoretical and experimental results reveal that P doping can independently modulate the electronic structure of Fe without affecting Ni, optimize the adsorption strength of OER intermediates at active sites and consequently facilitate the OER kinetics.