Enriching surface oxygen vacancies of spinel Co3O4to boost H2O adsorption for HER in alkaline media

Abstract

Oxygen-defective Co3O2.64S0.33 (namely CoO0.88S0.11) particulate spheres (PS) were prepared via the solid-state sulfurization of spinel Co3O4 at 300 °C in an Ar atmosphere. The introduction of sulfur (S) atoms was found to enrich the surface oxygen vacancies (Vso) remarkably in the as-derived CoO0.88S0.11 PS relative to pristine Co3O4 and CoS2, thus offering more active sites for catalytic reactions. Theoretical calculations were also performed to justify that the enrichment of Vso is favorable to boost the adsorption of H2O molecules. As a result, these CoO0.88S0.11 PS with exposed (111) facets demonstrated enhanced electrocatalytic performance in H2 evolution reaction (HER) with a low overpotential (OP) of 83 mV to realize a current density of 10 mA cm-2, and a high turnover frequency (TOF) of 1.589 H2 s-1 was obtained in 1 M KOH aqueous electrolyte.