Highly crystalline Ti-doped SnO2 hollow structured photocatalyst with enhanced photocatalytic activity for degradation of organic dyes

Abstract

We developed a facile infiltration route for synthesizing hollow-structured SnO₂ with an adjustable Ti doping content using SiO₂ microspheres as hard templates via an improved Stober method. The microstructures of as-prepared Ti-doped SnO₂ samples were characterized using XRD, SEM, TEM, XPS, and N₂ adsorption and desorption techniques. The photocatalytic activity of hollow-structured Ti-doped SnO₂ photocatalysts was investigated via the decomposition of methylene blue (MB) under UV and visible-light illumination in a photochemical reactor. It was revealed that hollow-structured Ti-doped SnO₂ spherical specimens display enhanced photocatalytic activity for decomposing MB compared with a pure SnO₂ sample. In comparison with pure SnO₂ hollow spherical sample, Ti-doped SnO₂ with a doping content of 20 mol% displays the highest photocatalytic activity, with 92% MB photocatalytically decomposed under UV light irradiation, with 54% MB photocatalytically decomposed under visible light irradiation, within a degradation time of 135 min, respectively. The relation between microstructure, optical response, and photocatalytic performance is discussed and analyzed. The enhancement in photocatalytic performance of Ti-doped SnO₂ can be attributed to the following reasons. Homogeneous doping of Ti into the lattice of SnO₂ prevents the recombination of electron–hole pairs and expands the range of usable excitation light to the visible-light region. In addition, the highly crystalline state, large surface area, and large pore size of Ti-doped SnO₂ also contribute to the improved photocatalytic activity of the Ti-doped SnO₂ samples.