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

Ultrafine SnO 2 nanocrystals are synthesized through a surfactant‐assisted solvothermal route in water–ethanol mixed media. SnO 2 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 SnO 2 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 SnO 2 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 TiO 2 . 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 SnO 2 samples. This synergism finally enhances the photocatalytic performance of the as‐prepared SnO 2 photocatalysts.