Ultrasmall SnO2 Nanoparticles: Influence of O-Vacancies on the Photocatalytic Degradation of Dyes

Synthetic dyes are widely used in various industries, which inevitably leads to increased water pollution. One of the recognized and waste-free techniques for water treatment is photocatalytic purification using semiconductor nanoparticles. However, the debate on how photocatalytic properties can be tuned through structural and morphological parameters using nanoparticle synthesis procedures remains open. In the present work, an approach to regulate UV-light-driven photocatalytic activity of spherical SnO2 nanoparticles using different structural parameters is demonstrated for the first time. Complex characterization of nanoparticles was provided using physicochemical methods with the help of computational methods. Special attention was paid to the development of a protocol of oxygen vacancy accounting within computer calculations for more realistic modeling of the interaction energy between nanoparticle surfaces and organic dye molecules of different natures. The photocatalysis mechanism was investigated according to the developed protocol, including the study of dye mixture kinetic degradation, dye-photocatalyst complex formation, and the ratio of oxygen vacancies and defects. It was shown that 93% of single dye decomposed in 7 min, and degradation of the dye mixture in a real water sample from Neva River achieved 60% after 40 min. It was possible to establish that this proof-of-concept study based on the combination of experimental and computational approaches can help develop the strategy of the rational design of photocatalysts promising for purification of real water samples.