Engineering P-doped Ni3S2-NiS hybrid nanorod arrays for efficient overall water electrolysis

Highlights: • P-doped Ni₃S₂-NiS nanorod arrays are developed. • P-doping activates the intrinsic catalysis activity. • P-doping improves charge transfer and catalysis kinetics. • P-doping induces numerous active sites. • High bifunctionality of 1.51 V at 10 mA cm⁻² for overall water splitting. -- Abstract: Exploring efficient non-metal catalysts to simultaneously drive hydrogen evolution and oxygen evolution is significantly important but challenging for practical overall water electrolysis. Herein, anionic doping engineering is adopted to develop phosphorus-doped hybrid Ni₃S₂-NiS nanorod arrays as efficient dualfunctional catalysts in alkaline media. P-doping and hetero-interface engineering induce improved active sites in the catalysis. Nanorod arrays structure is beneficial for charge and mass transfer, and P-doping promotes the conductivity and intrinsic catalysis activity. Serving as bifunctional catalyst, the present sample exhibits outstanding activities, with low overpotentials of 141 mV and 178 mV at current density of 10 mA cm⁻² for cathodic hydrogen and anodic oxygen evolution, respectively. In a two-electrode cell with P-doped Ni₃S₂-NiS as bifunctional electrode, the active overall water splitting activity (cell voltage of 1.51 V at 10 mA cm⁻² and 1.67 V at 100 mA cm⁻²) and good stability are obtained.