Natural Sunlight Driven Photocatalytic Degradation of Methylene Blue and Rhodamine B over Nanocrystalline Zn2SnO4/SnO2

Natural sunlight driven photocatalytic degradation of organic pollutants is a sustainable solution for water purification. Use of heterojunction nanocomposites in this process shows promise for improved photodegradation efficiency. In this work nanocrystalline Zn2SnO4/SnO2 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) confirmed formation of Zn2SnO4/SnO2 and heterojunctions between Zn2SnO4 and SnO2 nanoparticles. Photodegradation efficiency of 99.1% was achieved in 120 minutes with 50 mg of the photocatalyst for degradation of MB and 70.58% for degradation of RhB in the same conditions. In the multicomponent system the degradation efficiency of 97.87% for MB and 53.19% for RhB was obtained with only 15 mg of the photocatalyst. 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.