Spin Modulation of Antiperovskite Nitride for Industrial-Current-Density Seawater Electrolysis

Exploring electrocatalysts that possess both high activity and long-term durability is essential for the practical implementation of seawater electrolysis; however, achieving this goal remains a major bottleneck. Herein, a spin engineering strategy is proposed for antiperovskite nitride (CuNNi 3– x Mo x ) to boost its inherent catalytic activity. The partial substitution of Ni sites with Mo atoms induces a transition from low-spin state Ni 2+ (e g 2 t 2g 6 ) to high-spin state Ni 3+ (e g 2 t 2g 5 ). The Mo-substituted catalyst exhibits superior electrocatalytic performance, yielding low overpotentials of 212 mV for the hydrogen evolution reaction (HER) and 453 mV for the oxygen evolution reaction (OER) at a current density of 500 mA cm –2 . The practical viability of the spin-engineered antiperovskite catalyst is further demonstrated in an overall seawater electrolysis setup, which maintains stable operation at 500 mA cm –2 for over 1000 h. The experiments and density functional theory calculations reveal that spin state modulation reduces the electron population in the σ* orbitals, thereby strengthening *OH adsorption at Ni sites. This optimizes the binding energy of *OH and promotes the transformation to the active NiOOH phase, ultimately enhancing the OER kinetics.