Nanoflower-like BiOBr/TiO2 p-n heterojunction composites for enhanced photodegradation of formaldehyde and dyes

Abstract

A nanoflower-like BiOBr/TiO 2 p-n heterojunction photocatalyst was constructed and the possible photocatalytic mechanism was proposed. The construction of BiOBr/TiO 2 p-n heterojunction can significantly enhance the degradation of methyl orange (MO) and gaseous formaldehyde (HCHO) by photocatalysts. • A efficient nanoflower-like p-n heterojunction photocatalyst BiOBr/TiO 2 was prepared by simple solution coprecipitation. • This catalyst has enhanced photocatalytic degradation of dyes and formaldehyde. • P-n heterojunction effectively separates photogenerated carriers of BiOBr, hindering recombination of electrons and holes. The fabrication of p-n heterojunction is a smart strategy to improve the photocatalytic activity, because p-n junction can effectively promote the separation of photogenerated charges and improve the photocatalytic performance. Herein, a low cost nanoflower-like p-n heterojunction photocatalyst BiOBr/TiO 2 (abbreviated as BT-x) was prepared by simple solution coprecipitation method. Under visible light, BiOBr/TiO 2 p-n heterojunction photocatalyst showed enhanced photocatalytic activity in the degradation of Methyl Orange (MO) and gaseous formaldehyde (HCHO). The degradation rates of MO and HCHO by optimized composite BT-0.6 were 97% and 60% respectively. The p-type BiOBr with narrow band gap can effectively improve the visible light absorption, and its p-n heterojunction with TiO 2 can significantly improve the separation efficiency and transfer rate of photogenerated electron hole pairs. Meanwhile, multi-dimensional nanoflower structure is not only conducive to light reflection and improve light utilization, but also can expose more catalytic active sites. This p-n heterojunction composite material can be used as a new and promising catalyst for environmental applications.