Synergistic photothermal effects for enhanced hydrogen evolution of an S-scheme CdS@H0.95MoO3 photocatalyst: mechanistic insights and theoretical calculations

Abstract

Herein, CdS@H_0.95MoO₃ (L-CMx) composites with a core–shell structure were obtained through a solvothermal method combined with photo-reduction. Experimental results indicate that the photoreduction treatment will generate a large number of Mo⁴⁺ ions inside the composite, and the appearance of Mo⁴⁺ greatly increases the concentration of free electrons in the composite. Moreover, DFT calculations show that abundant Mo⁴⁺ ions can enhance the metallic properties of the material, leading to the generation of oxygen vacancies. This effectively modulates the ability of the composite to capture electrons and the resistance of photogenerated carrier interface migration. The S-scheme heterojunction between CdS and H_0.95MoO₃ achieved effective spatial separation of photogenerated charges. Also, the LSPR effect extends the light response range to the near-infrared region of 1400 nm, which significantly improves light utilization, while the photothermal effect further increases the surface temperature of the composites. The above reasons promote the photocatalytic reaction to proceed rapidly. Notably, the optimized L-CMx has superior H₂ evolution ability, reaching 20.9 mmol g⁻¹ h⁻¹ under visible light, and the AQY was 14.8% at 450 nm. Our work offers a feasible idea for the development of highly efficient full solar spectrum-driven photocatalysts by combining the synergetic effects of the S-scheme heterojunction, LSPR effect, and photothermal effect.