High-valence Mo-doped spinel oxides with abundant oxygen vacancies for efficient overall water splitting

Spinel oxides have emerged as promising electrocatalysts for overall water splitting. However, achieving high activity and stability for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) remains a challenge. Herein, we designed high-valence Mo-doped spinel oxides through in situ transformation of a CoMo-metal-organic framework (MOF) on carbon cloth (CC). The high-valence Mo doping promotes the formation of oxygen vacancies. The derived Co₅MoO_x-CC exhibits excellent activity for both the OER (310 mV@50 mA cm^-2) and the HER (317 mV@50 mA cm^-2). In an anion exchange membrane water electrolyzer (AEMWE), the catalyst operates stably for over 270 h at 70 mA cm^-2 and demonstrates superior catalytic activity (1.83 V@500 mA cm^-2).