Construction of hydrangea-like nanosheets with transition metal phosphide/phosphate heterostructure for boosting alkaline hydrogen evolution reaction activity

Alkaline water electrolysis represents a viable technological approach for producing green H 2 . However, the inherent low electrical conductivity and the hindrance in the hydrogen evolution reaction (HER) have led to slow kinetics of water splitting. Especially for the nickel‑iron layered double hydroxide (NiFe-LDH) catalyst loaded on nickel foam (NF), which is regarded as a potential alkaline HER catalyst. In this work, a phosphide/phosphate (NiP 2 /(CoHPO 4 ) 2 ·3H 2 O) heterostructure modified NiFe-LDH hydrogen evolution catalyst (NiP 2 -CHPO/NiFe-LDH/NF) is designed by the hydrothermal-electrodeposition method. Benefiting from enhanced electron dynamics and abundant active sites, the hydrangea-like biomimetic structure of the NiP 2 -CHPO/NiFe-LDH/NF catalyst exhibits outstanding HER catalytic activity. At 10 mA cm −2 , the HER overpotential is 74 mV, and the catalyst exhibits excellent stability for 35 h. In-situ infrared spectroscopy analysis reveals that the optimized interfacial water structure of NiP 2 -CHPO/NiFe-LDH/NF is the key factor for its enhanced performance. Theoretical calculations further confirm that the synergistic charge reconstruction effect of NiP 2 -CHPO and the rapid H ⁎ adsorption-desorption kinetics on the surface collectively contribute to the superior HER activity. This work demonstrates an efficient synthetic method for expanding the variety of phosphide/phosphate heterojunctions and provides new ideas for optimizing the hydrogen evolution efficiency of transition metal catalysts.