Interface engineering of FeP@CoMnP heterostructured nanoarrays for efficient and stable overall water splitting.

Electrocatalytic water splitting to generate high-quality hydrogen is an attractive renewable energy storage technology; however, it is still far from becoming a real-world application. In this study, we developed an effective and stable nickel foam-supported FeP@CoMnP heterostructure electrocatalyst for overall water splitting. As expected, the as-obtained FeP@CoMnP/NF electrocatalyst exhibits superb bifunctional catalytic activity and only requires extremely low overpotentials of 53 and 249 mV to achieve a current density of 10 mA cm for the hydrogen and oxygen evolution reactions, respectively. Moreover, a two-electrode electrolyzer assembled using FeP@CoMnP/NF as electrodes operates at the low cell voltage of 1.54 V at 10 mA cm, showing excellent long-term stability for 140 h. Theoretical calculations indicate that the surface electronic structure is effectively adjusted by the generated heterointerfaces between the FeP and CoMnP in a two-phase matrix, resulting in a Gibbs free energy of hydrogen adsorption close to zero and high intrinsic activity. This innovative strategy is a valuable route for producing low-cost high-performance bifunctional electrocatalysts for water splitting.