Mo/P Dual-Doped Co/Oxygen-Deficient Co₃O₄ Core–Shell Nanorods Supported on Ni Foam for Electrochemical Overall Water Splitting

The exploration for low-cost bifunctional materials for highly efficient overall water splitting has drawn profound research attention. Here, we present a facile preparation of Mo–P dual-doped Co/oxygen-deficient Co 3 O 4 core–shell nanorods as a highly efficient electrocatalyst. In this strategy, oxygen vacancies are first generated in Co 3 O 4 nanorods by lithium reduction at room temperature, which endows the materials with bifunctional characteristics of the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). A Co layer doped with Mo and P is further deposited on the surface of the Co 3 O 4– x nanorods to enhance the electrocatalytic hydrolysis performance. As a result, the overpotentials of HER and OER are only 281 and 418 mV at a high current density of 100 mA cm –2 in 1.0 M KOH, respectively. An overall water electrolytic cell using CoMoP@Co 3 O 4– x nanorods as both electrodes can reach 10 mA cm –2 at 1.614 V with outstanding durability. The improvement is realized by the synergistic effect of oxygen vacancies, Mo/P doping, and core–shell heterostructures for modulating the electronic structure and producing more active sites, which suggests a promising method for developing cost-effective and stable electrocatalysts.