Coral Reef-like CdS/g-C3N5 Heterojunction with Enhanced CO2 Adsorption for Efficient Photocatalytic CO2 Reduction

As a promising member of the carbon nitride family, nitrogen-rich g-C3N5has attracted significant attention because of its excellent light absorption performance. Nevertheless, its practical application in photocatalytic CO2reduction is hindered by severe photogenerated charge recombination and limited CO2adsorption capacity. Constructing a heterojunction has emerged as an effective strategy to mitigate charge recombination, thereby enhancing the photocatalytic performance of the catalyst. Herein, a series of CdS/g-C3N5-X heterojunction catalysts were prepared via an in situ hydrothermal approach. The obtained heterojunction catalysts exhibited a novel coral reef-like morphology which facilitated the exposure of additional active sites, thereby enhancing the adsorption and activation of CO2. Moreover, studies have shown that CdS can be anchored to the surface of g-C3N5through C-S bonds, forming a built-in electric field at the interface, which accelerated the separation and transfer of photogenerated charges. Consequently, the resulting heterojunction materials demonstrated high efficiency in photocatalytic CO2reduction with H2O as a sacrificial agent. In particular, CdS/g-C3N5-0.2 exhibited the maximum photocatalytic performance up to 22.9 μmol·g−1·h−1, which was 6 times and 3 times that of unmodified g-C3N5and CdS, respectively. The results indicated that the increased active sites and enhanced charge separation of the Cd/g-C3N5-0.2 catalyst were the primary reasons for its improved photocatalytic CO2reduction performance. This work provides a novel heterojunction-based photocatalyst for efficient CO2photocatalytic reduction, offering insights into the preparation of high-performance photocatalysts for sustainable energy applications.