Novel CdIn2S4 nano-octahedra/TiO2 hollow hybrid heterostructure: In-situ synthesis, synergistic effect and enhanced dual-functional photocatalytic activities

The development of highly efficient and multifunctional composite photocatalysts for both energy conversion and environmental governance has obtained great concerns. Here, a novel CdIn2S4/TiO2 (CIS/THS) hollow composite photocatalyst was firstly designed and synthesized via a facile in-situ growth process, where the CdIn2S4 nano-octahedra densely attached on the surface of TiO2 hollow spheres to form the unique hybrid heterostructure. The as-synthesized CIS/THS heterojunctions exhibit much superior photocatalytic activities for hydrogen evolution and Methyl Orange (MO) decomposition in comparison to pure CdIn2S4 and TiO2 hollow spheres. The experimental results display that the CIS/THS-3 sample with the 30 wt% of TiO2 presents the optimal photocatalytic H-2 production efficiency and its generation rate is 3.38 and 2.56 times as high as those of pure TiO2 and CdIn2S4. Besides, the as-synthesized CIS/THS-3 hybrid also possesses the best MO photodegradation performance and its rate constant is 11.43 and 8.34 times higher than those of pure TiO2 and CdIn2S4. The enhanced photocatalytic activities can be assigned to the synergistic effect, optimized light-harvesting capacity and the formation of hybrid heterostructure for boosting interfacial charge transfer and separation. Furthermore, based on the trapping experiments and ESR analysis, the possible type-II interface charge transport mechanism was also proposed. Our study may provide the direct guidance for constructing other hollow TiO2-based composite photocatalysts with superior photocatalytic water splitting and degradation performances.