Stabilizing NiFe sites by high-dispersity of nanosized and anionic Cr species toward durable seawater oxidation.

Cai, Zhengwei; Liang, Jie; Li, Zixiao; Yan, Tingyu; Yang, Chaoxin; Sun, Shengjun; Yue, Meng; Liu, Xuwei et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Electrocatalytic H<sub>2</sub> production from seawater, recognized as a promising technology utilizing offshore renewables, faces challenges from chloride-induced reactions and corrosion. Here, We introduce a catalytic surface where OH<sup>-</sup> dominates over Cl<sup>-</sup> in adsorption and activation, which is crucial for O<sub>2</sub> production. Our NiFe-based anode, enhanced by nearby Cr sites, achieves low overpotentials and selective alkaline seawater oxidation. It outperforms the RuO<sub>2</sub> counterpart in terms of lifespan in scaled-up stacks, maintaining stability for over 2500 h in three-electrode tests. Ex situ/in situ analyses reveal that Cr(III) sites enrich OH<sup>-</sup>, while Cl<sup>-</sup> is repelled by Cr(VI) sites, both of which are well-dispersed and close to NiFe, enhancing charge transfer and overall electrode performance. Such multiple effects fundamentally boost the activity, selectively, and chemical stability of the NiFe-based electrode. This development marks a significant advance in creating durable, noble-metal-free electrodes for alkaline seawater electrolysis, highlighting the importance of well-distributed catalytic sites.