Dual‐Cationic Doping Promoted Multi‐Defect Engineering of Ni ₁₂ P ₅ for Robust Seawater Electrolysis

Abstract Electrocatalytic seawater splitting offers a promising approach to sustainable hydrogen generation, contributing to the advancement of green energy technologies. Herein, the nanoflower‐like VFe co‐doped Ni 12 P 5 (denoted as VFe‐Ni 12 P 5 @C) are directly synthesized by low‐temperature plasma. The introduction of V and Fe modulates the electronic environment of Ni centers and increases the number of exposed active sites. In situ Raman spectroscopy further confirms that V‐Fe doping synergistically promote the in situ reconstruction of catalytically active (oxy)hydroxide species in Ni 12 P 5 matrices. The electrochemically reconstructed structure exhibits significant lattice distortion and enhanced structural disorder. Density functional theory calculations demonstrate that the defect‐rich structures derived from VFe‐Ni 12 P 5 @C facilitate the adsorption of key oxygen evolution reaction intermediates, thereby lowering reaction energy barriers and enhancing catalytic activity. As a result of these synergistic effects, the VFe‐Ni 12 P 5 @C catalyst requires only 251 and 274 mV overpotentials to achieve 100 mA cm −2 in 1 m KOH and alkaline seawater, respectively. When integrated into a full electrolyzer, the VFe‐Ni 12 P 5 @C||Pt@C system achieves 100 mA cm −2 at only 1.556 V under alkaline natural seawater, while maintaining stable operation over 100 h. This work underscores the critical role of dual‐cationic doping in tuning the structural and electronic properties of transition metal phosphides, thereby enabling efficient and durable water‐splitting electrocatalysis.