Oxyphilic CeO_x mediated in situ reconstruction of amorphous/crystalline heterointerface with enhanced hydroxyl...

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_x)-mediated amorphous/crystalline heterointerface engineering to enhance ^⁎OH coverage and leaching resistance in CeO_x/Mo-NiS_x for high-performance OER. CeO_x with an oxyphilic surface facilitates OH^- adsorption, promoting in situ reconstruction of NiS_x into nickel hydroxyl oxide (NiOOH) with significantly enhanced ^⁎OH coverage and thereby accelerating OER kinetics. Meanwhile, CeO_x-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_x/Mo-NiS_x catalyst exhibits exceptional OER activity with an ultralow overpotential of 140 mV at 10 mA cm^-2. It also demonstrates efficient hydrogen evolution reaction (HER) performance, requiring only 56 mV overpotential at 10 mA cm^-2. When integrated in an anion exchange membrane (AEM) water electrolyzer, the CeO_x/Mo-NiS_x-based system requires just 1.71 V to deliver 500 mA cm^-2 and maintains stable operation for 550 h. This CeO_x-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.