Oxyphilic CeO mediated in situ reconstruction of amorphous/crystalline heterointerface with enhanced hydroxyl coverage and active sites leaching resistance for alkaline oxygen evolution.

Enhancing anodic hydroxyl (OH) coverage and suppressing leaching of active metal sites are essential for developing efficient and durable alkaline oxygen evolution reaction (OER) electrocatalysts. Herein, we propose amorphous cerium oxide (CeO)-mediated amorphous/crystalline heterointerface engineering to enhance OH coverage and leaching resistance in CeO/Mo-NiS for high-performance OER. CeO with an oxyphilic surface facilitates OH adsorption, promoting in situ reconstruction of NiS into nickel hydroxyl oxide (NiOOH) with significantly enhanced OH coverage and thereby accelerating OER kinetics. Meanwhile, CeO-mediated amorphous/crystalline heterointerface modulation causes an upshift in the Ni 3d band center and strengthens the NiO covalent bond, inhibiting leaching of highly active Ni sites and improving catalyst stability. Consequently, the CeO/Mo-NiS catalyst exhibits exceptional OER activity with an ultralow overpotential of 140 mV at 10 mA cm. It also demonstrates efficient hydrogen evolution reaction (HER) performance, requiring only 56 mV overpotential at 10 mA cm. When integrated in an anion exchange membrane (AEM) water electrolyzer, the CeO/Mo-NiS-based system requires just 1.71 V to deliver 500 mA cm and maintains stable operation for 550 h. This CeO-mediated in situ reconstruction of amorphous/crystalline heterointerfaces enhances OH coverage and resists active-site leaching, advancing the design and mechanistic understanding of rare-earth-metal-reinforced alkaline OER electrocatalysts.