Sulfur oxidation mediated controllable reconstruction on LiCo_1.9Fe_0.1O₄ for boosted electrochemical water oxidation

Appropriate contact between catalysts and reactants calls for optimized exposure of active sites in the near-surface region, which can be accomplished by tuning the surface reconstruction degree. Understanding and conducting the controllable surface reconstruction of oxygen evolution reaction (OER) catalysts lays the foundation to finetune their OER activity. Herein, we explore the construction of a tunable amorphous oxyhydroxide shell on LiCo_1.9Fe_0.1O₄<i>via</i> heat-sulfurization, followed by electrochemical treatment. The 8-electron sulfide oxidation reaction (SOR) transforms the sulfide shell to amorphous oxyhydroxide and generates surface-anchored SO₄^2-, which act together to boost the OER. The electrocatalyst with optimal sulfurization exhibits 2.57 times higher than the current density at 1.6 V <i>vs.</i> RHE compared to the original LCFO. This work is dedicated to understanding controllable reconstruction and designing efficient OER electrocatalysts.