Structural and electronic modulation of (Fe,Ni)2P@Ni2P heterostructure for efficient overall water splitting at high current density

• (Fe, Ni) 2 P@Ni 2 P was obtained with unique structural and electronic characteristics. • The fusion of (Fe, Ni) 2 P and Ni 2 P makes (Fe, Ni) 2 P@Ni 2 P have good structural stability . • (Fe, Ni) 2 P@Ni 2 P shown excellent performance both at low and high current densities . • Overpotentials of 331 and 255 mV were required to reach 1000 mA cm −2 in OER and HER . • Continuously stable current density of 1000 mA cm −2 for up to 120 h can be realized. To meet the demand of practical applications, it is pivotal to obtain electrocatalysts with high performance and cost-effective at high current density in water splitting. Herein, (Fe, Ni) 2 P@Ni 2 P was obtained through precise modulation of their morphological and electronic properties. The fusion of (Fe, Ni) 2 P and Ni 2 P makes (Fe, Ni) 2 P@Ni 2 P have good structural stability. The unique porous structure can expose more active sites. Meanwhile, electrons transfer from electron-rich Ni 2 P to electron-negative (Fe, Ni) 2 P resulting in a low schottky barriers that promotes charge transfer efficiency. The unique morphological and electronic characteristics as well as the synergistic effect of (Fe, Ni) 2 P and Ni 2 P endow (Fe, Ni) 2 P@Ni 2 P with excellent catalytical performance. Ultra-low overpotentials of 331 and 255 mV are required to reach current density of 1000 mA cm −2 in oxygen evolution reaction and hydrogen evolution reaction, respectively. In overall water splitting, potentials of 1.702, 1.838 and 1.933 V are needed to achieve current densities of 100, 500 and 1000 mA cm − 2 , respectively. It also owns excellent fast response ability and a splendid long-term stability, with a continuously stable current density of 1000 mA cm −2 for up to 120 h. This work provides a new idea for the design of dual-function electrocatalysts for large-scale industrial hydrogen production.