Photocatalytic hydrogen production using semiconductor materials is one of the ideal processes for direct solar energy conversion. Sulphide semiconductor photocatalysts have attracted much attention due to their excellent solar spectrum responses and high photocatalytic activities. This article presents recent research progress in the development of visible light driven sulphide photocatalysts, focusing on the expansion of solar spectrum response and enhancement of charge separation efficiency. As is known, the ultimate goal of photocatalytic hydrogen production is to meet the practical energy demand of human beings. Thus, design of highly efficient and low cost sulphide photocatalysts with excellent sunlight response is highly desired. So we also highlight the crucial issues in the development of highly efficient sulphide photocatalysts without noble metal cocatalysts. The present paper is expected to provide important scientific reference for future works. Finally, the challenges and perspectives in this area are also discussed.

Cd_1−xZn_xS solid solution with nano-twin structures are synthesized and exhibit superior photocatalytic activities for H₂ evolution from water under visible light irradiation (λ ≥ 430 nm) without noble metal co-catalysts. Such Cd_0.5Zn_0.5S nanocrystals show the highest activity for hydrogen evolution with an extremely high apparent quantum yield (AQY = 43%) at 425 nm, achieving a hydrogen evolution rate of 1.79 mmol h⁻¹ without noble metals. The hydrogen evolution rate of 1.70 mmol h⁻¹ was achieved under simulated sunlight conditions (without infrared light). The “back to back” potential formed by parallel nano-twins in the Cd_1−xZn_xS crystals can significantly improve the separation of the photo-generated electrons/holes (preventing their recombination) thus enhancing the photocatalytic activity. Photodeposition experiments of noble metals strongly support such a mechanism. It is found that noble metals were selectively photo-deposited at central regions between the twin boundaries. The concentration of free electrons at the central region of twins was markedly higher and the twins can effectively separate the H₂ evolution sites (electrons) from oxidation reaction sites (holes).

High-quality metal halide perovskite single crystals have low defect densities and excellent photophysical properties, yet thin films are the most sought after material geometry for optoelectronic devices. Perovskite single-crystal thin films (SCTFs) would be highly desirable for high-performance devices, but their growth remains challenging, particularly for inorganic metal halide perovskites. Herein, we report the facile vapor-phase epitaxial growth of cesium lead bromide perovskite (CsPbBr₃) continuous SCTFs with controllable micrometer thickness, as well as nanoplate arrays, on traditional oxide perovskite SrTiO₃(100) substrates. Heteroepitaxial single-crystal growth is enabled by the serendipitous incommensurate lattice match between these two perovskites, and overcoming the limitation of island-forming Volmer–Weber crystal growth is critical for growing large-area continuous thin films. Time-resolved photoluminescence, transient reflection spectroscopy, and electrical transport measurements show that the CsPbBr₃ epitaxial thin film has a slow charge carrier recombination rate, low surface recombination velocity (10⁴ cm s^–1), and low defect density of 10¹² cm^–3, which are comparable to those of CsPbBr₃ single crystals. This work suggests a general approach using oxide perovskites as substrates for heteroepitaxial growth of halide perovskites. The high-quality halide perovskite SCTFs epitaxially integrated with multifunctional oxide perovskites could open up opportunities for a variety of high-performance optoelectronics devices.

Two kinds of defects in g-C ₃ N ₄ caused by high temperature calcination limit the photocatalytic H ₂ evolution activity. These defects are identified as amino/imino groups and controlling them will be key to improving the performance of the material for solar energy conversion.