Structure-Property Correlation in TiO2-CdS/Zeolite Hybrid Composites: Influence of Natural and Synthetic Supports on Lattice Strain and Photocatalytic Behavior

Background: The development of advanced materials catalyzing solar-driven degradation is essential for sustainable water remediation strategies. This study sheds light on how zeolitic supports influence the microstructural and charge-transfer properties of ternary photocatalysts. Methods: Hybrid Titanium dioxide (TiO2)-cadmium sulfide (CdS) composites supported on natural (clinoptilolite) and synthetic (NaA) zeolites were synthesized via an in situ sol–gel method. The structural and optical properties of these composites were characterized using instrumental techniques, and their photocatalytic performance was evaluated through the degradation of methylene blue (MB) under simulated solar light. Results: X-ray diffraction identified anatase as the dominant phase. Williamson-Hall analysis revealed a reduction in TiO2 crystal size (from 7.2 nm for bare TiO2 to 5.6 nm for the optimal composite) and support-dependent compressive lattice deformation. Specific surface area increased (from 65.88 to 78.91 m2/g) with the emergence of hierarchical porosity. The TiO2-CdS/clinoptilolite composite with a moderate zeolite content (TiO2-CdS/CLI0.5) exhibited the most balanced performance, featuring an optimal crystallite size, a moderate compressive lattice strain, a low recombination rate, and an absolute photocatalytic MB degradation of 53% (as well as 16% dark adsorption), outperforming synthetic NaA counterparts. Conclusions: The zeolitic support strongly influences structure–property relationships in TiO2-CdS/zeolite composites. By acting as rigid nanoreactors, the matrices induce microstrain and facilitate charge separation via a direct Z-scheme mechanism, thereby enhancing visible-light photocatalysis.