Asymmetric tacticity navigates the localized metal spin state for sustainable alkaline/sea water oxidation.

Liu, Yaoda; Li, Lei; Li, Xuning; Xu, Yifan; Wu, Dongshuang; Sakthivel, Thangavel; Guo, Zhixin; Zhao, Xiaoxu et al. · Sci Adv · 2025

basic_science · Level V

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Abstract

Anodic oxygen evolution reaction (OER) that involves a spin-dependent singlet-to-triplet oxygen changeover largely restrains the water electrolysis efficiency for hydrogen production. However, the modulation of spin state is still challengeable for most OER catalysts, and there remains a debate on deciphering the active spin state in OER. Here, we pioneered an asymmetric Fe-incorporated NiPS<sub>3</sub> tactic system to retune the metal localized spin for efficient OER electrocatalysis. It is unraveled that the synergistic effect of medium-spin Fe<sup>III</sup> site and P/S coordination can effectively boost OER activity and Cl resistance selectivity in alkaline/sea water. Resultantly, the Fe/NiPS<sub>3</sub>-based asymmetric electrodes exhibit low cell voltages of 1.50 volts/1.52 volts in alkaline/sea water at 10 milliamperes per square centimeter, together with a sustainable retention for 1000 hours. It also delivers the durable performance in anion exchange membrane water electrolyzers with a low operation voltage at 45°C. This research navigates the atomic localized spin state as the criterion in rationalizing efficient nonprecious alkaline/sea water oxidation electrocatalysts.