Achieving Synergy with a Potential Photocatalytic Z-Scheme: Synthesis and Evaluation of Nitrogen-Doped TiO₂/SnO₂ Composites

Nitrogen-doped titania (N-TiO 2 )/tin oxide (SnO 2 ) composites were synthesized and evaluated as photocatalysts for the first time. These composites represent a potential new class of Z-scheme photocatalysts wherein the enhanced light absorption properties of N-TiO 2 are anticipated to couple with the observed benefits of composite TiO 2 /SnO 2 systems. The N-TiO 2 /SnO 2 composites were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 -adsorption, diffuse reflectance spectroscopy (DRS), electron paramagnetic resonance (EPR) spectroscopy, and scanning electron microscopy (SEM). It was found that composites with low SnO 2 content display enhanced photocatalytic properties under visible light irradiation when compared to standards: TiO 2, N-TiO 2, SnO 2, and TiO 2 /SnO 2 composites. This enhancement is attributed to a synergistic effect between the two composite components and changes in the textural properties of the materials upon composite formation. Significantly, the enhanced performance demonstrates the importance of evaluating new composite photocatalysts.