Enhanced Photocatalytic Properties of SnO2 Nanocrystals with Decreased Size for ppb-level Acetaldehyde Decomposition

Ultrafine SnO2 nanocrystals are synthesized through a surfactant-assisted solvothermal route in water-ethanol mixed media. SnO2 photocatalysts with sizes of about 4, 8, and 12 nm are prepared through controllable annealing of the as-synthesized nanocrystals. Brunauer-Emmett-Teller (BET) specific surface areas of calcined SnO2 samples increase dramatically as their sizes decrease. Photocatalytic performances of the as-obtained catalysts for decomposing ppb-level (parts per billion) acetaldehyde are tested in a continuous glass-plate reactor. Result shows that SnO2 photocatalysts of about 4 nm with a large BET surface area of 130 m(2)g(-1) exhibit the best photocatalytic oxidation properties, which is comparable to that of Degussa P25 TiO2. Analysis by using the unimolecular Langmuir-Hinshelwood reaction model indicates that the abilities of adsorption have well synergized with the photocatalytic reaction activities in the as-obtained SnO2 samples. This synergism finally enhances the photocatalytic performance of the as-prepared SnO2 photocatalysts.