Spatially separated catalytic sites supplied with the CdS–MoS2–In2O3 ternary dumbbell S-scheme heterojunction for enhanced photocatalytic hydrogen production

Abstract

Inspired by natural photosynthesis, the development of high-efficiency and low-energy hydrogen production catalysts is essential to alleviate environmental problems. Here, the CdS nanorods are the main body, and the CdS–MoS₂ dumbbell structure is synthesized by the solvothermal method to make the photogenerated electrons flow along the one-dimensional axis. The nanoconfinement effect of MOF-derived In₂O₃ hollow hexagonal prisms greatly expands the spectral absorption range of the composite photocatalysts. The CdS–In₂O₃ S-scheme heterojunction was constructed by a simple electrostatic-driven self-assembly method. In situ irradiation X-ray photoelectron spectroscopy analysis shows that the internal electric field drives the photogenerated electrons in In₂O₃ to move to CdS, forming a S-scheme heterojunction of CdS–In₂O₃, which greatly promotes the separation of electron–hole pairs. In₂O₃ is combined with the sidewalls of the CdS–MoS₂ dumbbell to weaken the surface oxidation kinetics, thereby inhibiting the surface photo-corrosion reaction. MoS₂ promotes the CdS–In₂O₃ S-scheme heterojunction photocatalyst to show significant photocatalytic hydrogen evolution performance. The hydrogen production rate under the irradiation of a 300 W simulated light source is 198.58 mmol h⁻¹ g⁻¹, and natural light can produce a large number of visible bubbles. The effective separation of reduction and oxidation functional sites in space, the directional transfer of photogenerated electrons–holes, and the construction of S-scheme heterojunctions are the main factors for the significant increase in the catalytic activity of semiconductor photocatalysts. This work provides an effective strategy for designing metal sulfide-based photocatalysts with high activity and high stability of water-splitting properties.