Enhanced photocatalytic activity of p (BaSnO3)-n (anatase/rutile/brookite TiO2) heterojunction composites by efficient interfacial charge transfer

In the present work, new BaSnO3/TiO2 p-n heterojunction composite photocatalysts based on p-type BaSnO3 and n-type TiO2 with anatase/rutile/brookite three-phase coexisting were constructed. The microstructure and photocatalytic performance of the prepared composites were investigated. The results show that pure TiO2 (PT) consists of three phases including anatase, rutile and brookite. Mott-Schottky curves prove that BaSnO3 and TiO2 are coupled to form p-n heterojunctions, and the built-in electric field generated at heterogeneous interfaces promotes the separation of photogenerated charges and enhances the photocatalytic performance. When the Ba/ Ti molar ratio is 5%, 5%BaSnO3/TiO2 (5%BT) exhibits the highest photocatalytic activity. The first-order reaction rate constant of 5%BT is 0.157 min-1, which is 1.8 and 2.2 times higher than that of commercial P25 (0.089 min-1) and PT (0.071 min-1), respectively. Furthermore, a mechanism of p-n heterojunctions improving the photocatalytic performance is proposed based on band potentials analysis and ESR results.