In situ Ba2+ exchange in amorphous TiO2 hollow sphere for derived photoelectrochemical sensing of sulfur dioxide

The development of cost-effective and highly sensitive SO 2 sensors is an urgent task since SO 2 causes worldwide serious environmental security and human diseases. Herein, a first photoelectrochemical (PEC) sensing platform for SO 2 was constructed based on Ba 2+ doped amorphous TiO 2 hollow spheres. They were successfully prepared by SiO 2 template method before in situ Ba 2+ ions exchanging and doping. Before assay, SO 2 was oxidized by hydrogen peroxide and generated H 2 SO 4 , which was further neutralized by NaOH resulting in the generation of Na 2 SO 4 . When it reacted with Ba 2+ -doped TiO 2 hollow spheres, the produced BaSO 4 nanoparticles leaded to the photocurrent remarkably decreased due to the photo-induced electron pathways shut down. The fabricated PEC sensor was linear with the concentration of SO 4 2− in the range from 1 to 4000 pmol L −1 with a detection limit of 0.4 pmol L −1 . The other conventional species did not interfere in the detection of SO 4 2− in aqueous system and the fabricated PEC sensor was successfully applied in monitoring of SO 2 in industry waste gas. It demonstrated good performance including wide dynamic linear range, high selectivity, ultrasensitivity, excellent stability and low cost. This strategy paves a new way for other similar air pollutants.