Facile Construction of Cu₃P/ZnIn₂S₄ Heterojunctions for Efficient Photocatalytic Hydrogen Evolution

The ZnIn2S4 (ZIS) powder that was synthesized by the hydrothermal method has excellent photocatalytic H2 evolution activity. Cu3P (CP) is a p-type semiconductor, often associated with an n-type catalyst to form a p–n junction by balancing the diffusion of the carrier with the electrical migration. Therefore, it is well suited as a photocatalytic cocatalyst. To further improve the hydrogen production activity of the semiconductor photocatalyst, the Cu3P/ZnIn2S4 (CP/ZIS) samples are obtained through simple mechanical mixing. X-ray photoelectron spectroscopy, X-ray diffraction, surface photovoltage, ultraviolet–visible diffuse reflection light, scanning electron microscopy, and transmission electron microscopy techniques were used to investigate the crystal morphologies, properties, and optical properties of a CP/ZIS photocatalyst. The optical properties, microstructures, and composition of surface elements of the composite have been fully characterized. Experiments found that the mixed sample absorbed a wider light range and had a better hydrogen production rate compared to the pure ZnIn2S4. When the doping content of the supported Cu3P cocatalyst is 0.5%, the optimal hydrogen production rate of the sample CP/ZIS is 5466 μmol·g–1·h–1, which is 1.7 times that of pure ZnIn2S4. A heterojunction was formed between ZnIn2S4 and Cu3P to favor the migration and separation of carriers, and thus photocatalytic activity on CP/ZIS, facilitating the rate of photocatalytic H2 production.