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

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)₂P@Ni₂P was obtained through precise modulation of their morphological and electronic properties. The fusion of (Fe, Ni)₂P and Ni₂P makes (Fe, Ni)₂P@Ni₂P have good structural stability. The unique porous structure can expose more active sites. Meanwhile, electrons transfer from electron-rich Ni₂P to electron-negative (Fe, Ni)₂P 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)₂P and Ni₂P endow (Fe, Ni)₂P@Ni₂P 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.