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-<i>x</i>Mo_<i>x</i>) to boost its inherent catalytic activity. The partial substitution of Ni sites with Mo atoms induces a transition from low-spin state Ni²⁺ (e_g² t_2g⁶) to high-spin state Ni³⁺(e_g² t_2g⁵). 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.