Ultrathin NiCo Bimetallic Molybdate Nanosheets Coated CuOx Nanotubes: Heterostructure and Bimetallic Synergistic Optimization of the Active Site for Highly Efficient Overall Water Splitting

Abstract Rational design and construction of bifunctional electrocatalysts with excellent activity and durability is imperative for water splitting. The regulation of the local electronic structure of the active metal sites in polymetallic composites provides a basic idea. Herein, the ultrathin bimetallic molybdate nanosheets are evenly deposited on the CuO x hollow nanotubes on the copper foam substrate to form a hierarchical heterostructure, which can be used as an efficient bifunctional electrocatalyst for overall water splitting. Experimental results prove that the introduction of Ni to form a double metal salt molybdate and CuO x heterostructure design can be optimized by Co cation as best electronic structure of electric catalytic activity center, and can effectively promote the generation of CoOOH active phase at the same time, so that can skillfully optimize the binding strength between the Co site and the oxygen‐containing intermediate, and enhancing catalytic activity. When it is used in the overall water splitting of a double‐electrode alkaline electrolytic cell, the cell voltage of CoNiMoO 4 ‐21/CuO x /CF is 1.532 V at 50 mA cm −2 , far exceeding most of the reported conventional bifunctional electrocatalyst. This work has contributed to understanding the central active sites of polymetallic composites and has provided a useful value for the design of efficient electrocatalysts.