| Summary: | The natural sunlight driven photocatalytic degradation of organic pollutants is a sustainable solution for water purification. The use of heterojunction nanocomposites in this process shows promise for improved photodegradation efficiency. In this work, nanocrystalline Zn<sub>2</sub>SnO<sub>4</sub>/SnO<sub>2</sub> obtained by the solid-state synthesis method was tested as a heterojunction photocatalyst material for the degradation of methylene blue (MB) and Rhodamine B (RhB) dyes as single and multicomponent systems in natural sunlight. Characterization of the structure and morphology of the synthesized nanocomposite using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS), and photoluminescence (PL) spectroscopy confirmed the formation of Zn<sub>2</sub>SnO<sub>4</sub>/SnO<sub>2</sub> and heterojunctions between Zn<sub>2</sub>SnO<sub>4</sub> and the SnO<sub>2</sub> nanoparticles. A photodegradation efficiency of 99.1% was achieved in 120 min with 50 mg of the photocatalyst for the degradation of MB and 70.6% for the degradation of RhB under the same conditions. In the multicomponent system, the degradation efficiency of 97.9% for MB and 53.2% for RhB was obtained with only 15 mg of the photocatalyst. The degradation of MB occurred through N-demethylation and the formation of azure intermediates and degradation of RhB occurred through sequential deethylation and fragmentation of the xanthene ring, both in single and multicomponent systems.
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