Self-assembled CdS/C₃N₅ heterostructure for photocatalytic CO₂ reduction

Quantum dots (QDs) are promising alternatives for CO₂ photoreduction catalysts due to their excellent photogenerated charge transfer capabilities and tunable band positions. However, their photocatalytic performance is often limited by rapid charge carrier recombination and a lack of sufficient CO₂ adsorption sites. Constructing heterostructures is a well-established strategy to address these challenges. Herein, a CdS/C₃N₅ heterojunction with CdS QDs dispersed on C₃N₅ nanosheets was successfully fabricated via a simple self-assembly method. The resulting composite exhibited significantly enhanced visible-light-driven CO₂ reduction performance with CO as the primary reduction product, alongside negligible amounts of CH₄ and H₂. The CO evolution rate reached 4.9 mmol g⁻¹ h⁻¹, which is approximately 80 times and 4 times higher than that of C₃N₅ and CdS QDs, respectively. The outstanding performance and stability of the CdS/C₃N₅ heterojunction can be attributed to the uniform dispersion and intimate interfacial contact between the components, which facilitate efficient charge separation and rapid carrier transfer. This work provides a viable strategy for the fabrication of highly efficient heterostructure photocatalysts for CO₂ reduction.