Nano/Microscale Integrated Mushroom-Shaped Hydrophilic CoP@Ni-CoP with Optimized Gas Bubble Release for High-Performance Water Splitting Catalysis

Overall water splitting based on electrocatalysis is an easily constructed and cost-effective technology for achieving clean and renewable hydrogen energy on a large scale. Herein, we demonstrate the investigation of multiscale integrated mushroom-shaped cobalt phosphide@nickel-cobalt phosphide (denoted CPNCP) as a catalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions. The catalyst with a unique nano/microscale 3D “body” and “head” structure can be grown directly on a nickel substrate, promoting high conductivity, high hydrophilicity, and effective gas bubble release, bringing in a prospective candidate for practical water splitting devices. Furthermore, the practical relevance of CPNCP as a bifunctional catalyst for the overall water splitting reaction is revealed, with 10 mA·cm–2 to achieve current density at a low overpotential of 1.49 V and maintained at 10 and 200 mA·cm–2 for 40 h with little degradation. Also, the continuous reverse water splitting for over 6 h is capable, demonstrating CPNCP’s high endurance toward constant power interruption. The turnover frequencies are calculated to be 3.208 and 1.072 s–1 for HER and OER, respectively, describing an excellent performance of CPNCP. This work may inspire optimizing structures of transition-metal-based nanomaterials, promoting their applications in other renewable energy options.