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

Abstract

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.