Photochemical growth of nanoporous SnO2 at the air–water interface and its high photocatalytic activity

Nanoporous SnO2 containing two types of porous structures has been prepared at the air–water interface by a new photochemical route. This room temperature method is surfactant- and template-free, low-cost, and high-yield. Only SnSO4 and diluted H2SO4 aqueous solution were used as precursors. Under ultraviolet (UV) light irradiation, Sn2+ absorbs photons to produce metallic tin and stannic ions. The metallic tin reacts immediately with oxygen in the air to form SnO2. Meanwhile, a small amount of tin can also react with H2SO4 and is dissolved in the solution to form one type of nanoporous structure. The stannic ions are converted to insoluble H2SnO3 which dehydrates to form the other type of porous SnO2 structure during the subsequent drying process. The as-prepared porous SnO2 has higher photocatalytic activity than Degussa P25 for degrading methyl orange (MO) solution under the irradation of a xenon lamp.