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 Co3O4 core-shell nanorods as a highly efficient electrocatalyst. In this strategy, oxygen vacancies are first generated in Co3O4 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 Co3O4-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@Co3O4-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.