Solid-solution-tuned d-band center boosts alkaline hydrogen evolution

d-band center engineering in metal phosphide offers promising avenues to improve hydrogen evolution reaction (HER) activity through electronic modulation. However, precise d-band regulation via theoretically feasible double heteroatom modification remains challenging. This work demonstrates a ternary metal phosphide (Fe0.5V0.5NiP) engineered through Fe/V integration to optimize the d-band center of nickel phosphide (Ni2P). Combined experimental and theoretical analyses reveal that Fe and V synergistically shift the d-band center closer to the Fermi level, thereby balancing absorption/desorption of HER intermediates. Notably, V significantly reduces water dissociation energy barriers, while Fe-V cooperation optimizes hydrogen-adsorption Gibbs free energy. The Fe0.5V0.5NiP achieves exceptional alkaline HER performance, delivering overpotentials of 67.9 mV (10 mA/cm2) and 203.1 mV (100 mA/cm2) in 1 mol/L KOH, surpassing the benchmark Pt/C. Remarkably, it maintains stability for 100 consecutive hours without degradation. This work provides atomic-level insights on dual-heteroatom modified d-band tuning and establishes a rational design paradigm for high-performance metal phosphide electrocatalyst.