Enhanced Photocatalytic H2 Generation of S-Scheme MoS2/CoMoO4 Heterojunction with Enriched Sulfur Vacancy

Abstract

To investigate the effect of varying concentrations of sulfur (S) vacancies in MoS₂ (MS) on photocatalytic hydrogen evolution reaction (HER), a series of MS photocatalysts with different S vacancy concentrations were synthesized via a hydrothermal method. The results indicate that the as-prepared MS/CMO composite catalyst exhibits optimal HER at a composite ratio of 10% and a sulfur vacancy concentration of 1:6, achieving a hydrogen evolution amount of 332 μmol within 5 h. The MS₆/CMO composite exhibits an apparent quantum efficiency of 12% at a wavelength of 450 nm. Electron paramagnetic resonance (EPR) analysis reveals that the sulfur vacancy concentration in the composite catalyst significantly influences the photocatalytic activity. Mott–Schottky measurements reveal that both CMO and MS display n-type semiconducting behavior, and are supported by XPS characterization, DFT simulations, and electronic band structure studies. These findings pave a novel pathway for designing vacancy-modulated catalysts, which hold significant implications for enhancing catalytic efficiency and material stability. Moreover, this work broadens the research perspectives in the field of HER by providing fundamental mechanistic insights and practical design strategies. These findings pave a novel pathway for designing vacancy-modulated catalysts, which hold significant implications for enhancing catalytic efficiency and material stability.