The Ni,Cd Heteroatoms‐Initiated Synergistic Tuning of Electron Configuration in Fe 2 VO 4 Nanosheets Electrocatalysts to Profoundly Stabilize Alkaline Seawater Electrolysis

ABSTRACT The architecture of high‐efficiency and long‐term seawater‐splitting electrocatalysts capable of suppressing the undesirable chloride electrochemistry and corrosion is paramount for seawater electrolysis technology. Herein, a bifunctional electrocatalyst composed of Ni,Cd‐codoped iron vanadate supported on nickel foam (denoted as Ni,Cd‐Fe 2 VO 4 /NF) is rationally designed. The triggered synergistic effect of Ni,Cd co‐doping can modulate the electron configuration of Fe 2 VO 4 , which not only optimizes the adsorption energy of reactants and intermediates and simultaneously strengthens the electron transfer ability, but also stabilizes the Fe/V sites with high valence in Fe 2 VO 4 , which preferentially adsorbs H 2 O and OH − while electrostatically repelling Cl − during the seawater electrolysis. Consequently, the Ni,Cd‐Fe 2 VO 4 /NF electrocatalyst only requires extremely low overpotentials of 236 and 254 mV for OER and HER to reach a current density of 500 mA cm −2 in 1 m KOH + seawater, respectively. And it also maintains stable operation for 200 h with negligible performance attenuation. Notably, the zero‐gap electrolyzer assembled with Ni,Cd‐Fe 2 VO 4 /NF electrocatalysts exhibits an ultralow voltage of 1.74 V at a current density of 500 mA cm −2 in 1 m KOH + seawater, accompanying an ultra‐long lifespan of 3000 h without significant performance degradation, underscoring its great potential for large‐scale practical application.