Glucose-tailored SnO2/TiO2/RGO ternary composite for degradation of organic pollutants

Abstract

A glucose-tailored SnO2/TiO2/reduced graphene oxide ternary composite is developed for a high-performance photocatalyst. First, SnO2 nanoparticles are deposited on graphene oxide nanosheets through a hydrolysis method. In the presence of glucose, TiO2 nanoparticles are synthesized on SnO2/graphene oxide via a hydrothermal reaction. The influence of glucose dose and Sn/Ti ratio on the photocatalytic performance is studied. When used for degradation of rhodamine B and methylene blue, the optimized composite exhibits much greater photocatalytic activity than commercial P25, and degrades 97.6% of rhodamine B and 99.5% of methylene blue in 40 min. The superior performance is attributed to the tailored microstructure and SnO2/TiO2 heterojunction. Glucose prevents the stacking of graphene nanosheets, adjusts the pore structure, and results in the formation of a composite with a large specific surface area and hydrophilicity, which facilitates dispersion of the catalyst powder in water and improves the physical adsorption to dye molecules. Furthermore, the SnO2/TiO2 heterojunction formed on conductive reduced graphene oxide reduces the band gap and broadens the light absorption range, reduces the charge transfer resistance, and promotes the separation and transfer of carriers. Moreover, ·O2− and ·OH radicals are both generated for degradation of organic pollutants through a redox reaction. Finally, a possible photodegradation mechanism is proposed as a Z-scheme transfer mode.