Mott-Schottky heterojunctions of ultrafine Ni3Fe confined in amorphous molybdenum oxide for efficient and durable overall water electrolysis

NiFe alloys are highly active towards oxygen evolution reaction (OER), and it is important to further enhance their catalytic activity and working stability. Herein, a series of Mott-Schottky electrocatalysts of ultrafine Ni3Fe confined in amorphous molybdenum oxide (Ni3Fe/MoOx) are fabricated via hydrogenation treatment. The experimental results and computational calculations show that the amorphous MoOx improves the surface wettability, modulates the electronic structure, accelerates the charge transfer, favors the generation of NiOOH species, and facilitates the formation of the *OOH intermediates. The Ni3Fe/MoOx phase interfaces are engineered by controlling the MoOx content to optimize the catalytic activity, and the Ni3Fe/MoOx-0.5 catalyst with the optimized Mott-Schottky heterojunction exhibits the highest catalytic activity with an overpotential of 224 mV at 10 mA cm−2. Additionally, the amorphous MoOx layer greatly enhances the working stability of the Ni3Fe, showing almost no activity degradation in both two-electrode and three-electrode systems.