Phase-Reconstruction of S-Doped (NiCo)<sub>6</sub>W<sub>6</sub>C for Efficient and Stable Oxygen Evolution Reaction Electrocatalysis.

Liu, Yang; Yao, Rui-Qi; Chen, Li-Bo; Dai, Tian-Yi; Sun, Xin-Ying; Zeng, Shu-Pei; Zhou, Zhi-Lan; Wang, Ying et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Developing highly active and stable nonprecious electrocatalysts toward sluggish alkaline oxygen evolution reaction (OER) is essential for large-scale green hydrogen production via electrochemical water splitting. Here we report phase and surface co-reconstruction of S-doped (NiCo)<sub>6</sub>W<sub>6</sub>C nanoparticles into (NiCo)C<sub><i>x</i></sub> with amorphous electroactive NiCoOOH layer for highly efficient alkaline OER by W dissolution and NiCo surface oxidation. The W dissolution results in the formation of Brønsted base WO<sub>4</sub><sup>2-</sup> ions, which electrostatically accumulate around electrode to promote water dissociation into abundant OH* intermediates, in situ constructing a locally strong alkaline microenvironment to facilitate OH* adsorption on NiCoOOH sites and trigger lattice-oxygen oxidation path. As a result, the heterostructure electrode exhibits superior OER electrocatalysis with low Tafel slope of ∼35 mV dec<sup>-1</sup> in 1 M KOH. It delivers high ampere-level current density of ∼1 A cm<sup>-2</sup> at a low overpotential of 275 mV, and maintains extraordinary stability for over 1000 h.