Highly efficient photocatalytic methylene blue degradation over Sn(O,S)/TiO₂ photocatalyst fabricated via powder atomic layer deposition of SnO and subsequent sulfurization

In this work, tin oxysulfide coated TiO₂ nanoparticles for photocatalytic pollutant degradation were fabricated via a two-step vacuum process which involves powder atomic layer deposition (PALD) of SnO on TiO₂ nanoparticles followed by sulfurization annealing. The physical and chemical properties of the Sn(O,S)/TiO₂ nanoparticles were characterized and compared with TiO₂ and SnO/TiO₂. From the methylene blue (MB) degradation test, the photocatalytic activities of Sn(O,S)/TiO₂ were examined. The Sn(O,S)/TiO₂ showed ~ 6.7 and 16-fold improved MB degradation rate constants of 0.002 and 0.114 min⁻¹ compared to the pristine TiO₂ under visible light and Xe lamp irradiations, respectively. This may be attributed to the synergetic effects of enhancing the electron-hole charge separation and light absorption characteristics.