Facile Construction of a Hollow In₂S₃/Polymeric Carbon Nitride Heterojunction for Efficient Visible-Light-Driven CO₂ Reduction

The development of high-efficiency photocatalysts is of great importance to realize robust solar-driven CO₂ conversion; however, the low carrier separation efficiency and poor light absorption ability usually limit the performance of the photocatalysts. Herein, a hollow In₂S₃/polymeric carbon nitride (IS/CN) heterojunction was prepared via electrostatic self-assembly and in situ sulfidation under solvothermal conditions. The intimate interfacial contact between the IS and CN facilitates the construction of an effective heterojunction, as demonstrated by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The optimized IS/CN-5 sample exhibits a high CO evolution rate of 483.4 μmol g^–1 h^–1, which is 99 and 6 times as high as that of IS and CN, respectively. The improved charge separation and transfer efficiency, the hollow nanotube structure, and the enhanced CO₂ adsorption ability are the reasons for the excellent photocatalytic activity. Besides, a possible photocatalytic mechanism of CO₂ reduction by the IS/CN heterojunction was proposed on the basis of the band structures. This work provides an effective and facile strategy to construct hollow semiconductor heterojunctions for photocatalytic applications.