Assessment of the superior photocatalytic properties of Sn2+-containing SnO2 microrods on the photodegradation of methyl orange

A Sn 2+ -containing SnO 2 material was synthesized via a simple hydrothermal route, and its characterization demonstrated that it presented a microrod morphology with rutile SnO 2 crystalline structure. Sn 2+ ions were detected in the interior of the material and no other impurities, such as Sn 2+ -containing tin oxide phases (Sn 2 O 3 , Sn 3 O 4 , SnO) were detected. The material’s optical properties have shown the absorption of a considerable fraction of visible light up to wavelengths of 671 cm -1 , contrastingly to ordinary SnO 2 . The analysis of the internal crystalline structure of a single microrod was carried out with a Focused Ion beam microscope, confirming that the material was highly defective with strong polycrystalline nature down to the nanoscale. The results indicated that the constituent Sn 2+ ions occupy intergranular sites in a rutile SnO 2 mesocrystalline structure, and that Sn 2+ states were responsible for the material’s superior photoactivity. The photocatalytic performance of the material was much higher than those of commercial TiO 2 and SnO 2 materials, and it decomposed nearly all methyl orange dye content in water (10 mg L ‑1 ) in 6 min under UV irradiation for a photocatalyst dose of 5.33 g L ‑1 . The photodegradation of methyl orange was also verified under visible light.