Single-atom vacancy defect to trigger high-efficiency hydrogen evolution of MoS2

Defect engineering is widely applied in transition metal dichalcogenides (TMDs) to achieve electrical, optical, magnetic and catalytic regulation. Vacancies, regarded as a type of extremely delicate defect, are acknowledged to be effective and flexible in general catalytic modulation. However, the influence of vacancy states in addition to concentration on catalysis still remains vague. Thus, via high throughput calculations, the optimized sulfur vacancy (S-vacancy) state in terms of both concentration and distribution is initially figured out among a series of MoS2 models for the hydrogen evolution reaction (HER). In order to realize it, a facile and mild H2O2 chemical etching strategy is implemented to introduce homogeneously distributed single S-vacancies onto MoS2 nanosheet surface. By systematic tuning of the etching duration, etching temperature and etching solution concentration, comprehensive modulation of the S-vacancy state is achieved. The optimized HER performance reaches a Tafel slope of 48 m...