Synergistically Enhanced Photocatalytic Degradation by Coupling Slow-Photon Effect with Z-Scheme Charge Transfer in CdS QDs/IO-TiO2 Heterojunction

Lower light absorption and faster carrier recombination are significant challenges in photocatalysis. This study introduces a novel approach to address these challenges by anchoring cadmium sulfide quantum dots (CdS QDs) on inverse opal (IO)-TiO2, which increases light absorption and promotes carriers' separation by coupling slow-photon effect with Z-scheme charge transfer. Specifically, the IO-TiO2 was created by etching a polystyrene opal template, which resulted in a periodic structure that enhances light absorption by reflecting light in the stop band. The size of CdS quantum dots (QDs) was regulated to achieve appropriate alignment of energy bands between CdS QDs and IO-TiO2, promoting carrier transfer through alterations in charge transfer modes and resulting in synergistic-amplified photocatalysis. Theoretical simulations and electrochemical investigations demonstrated the coexistence of slow-photon effects and Z-scheme transfer. The system's photodegradation performance was tested using rhodamine B as a model. This novel hierarchical structure of the Z-scheme heterojunction exhibits degradability 7.82 and 4.34 times greater than pristine CdS QDs and IO-TiO2, respectively. This study serves as a source of inspiration for enhancing the photocatalytic capabilities of IO-TiO2 and broadening its scope of potential applications.