A photocatalytic superhydrophobic coating with p–n type BiOBr/α-Fe2O3 heterojunctions applied in NO degradation

Abstract

Coal combustion generates soot-type air pollution, and NO, as a typical pollutant, is the main haze-causing pollutant. The degradation of NO by means of photocatalytic superhydrophobic multifunctional coatings is both durable and economical. The precipitation method was employed to create a p–n type BiOBr/α-Fe₂O₃ photocatalytic binary system. BiOBr/α-Fe₂O₃ nanoparticles were combined with polydimethylsiloxane (PDMS) in a butyl acetate solution to produce a BiOBr/α-Fe₂O₃/PDMS/butyl acetate emulsion, and photocatalytic superhydrophobic coatings were then prepared using a one-step cold-spraying method. Photocatalytic oxidation experiments were conducted using a low concentration of NO as the targeted degradant. The results indicate that BiOBr/α-Fe₂O₃ photocatalytic heterojunctions were successfully prepared with NO removal up to 65%, indicating that the formation of p–n type heterojunctions enhances the light absorption range and improves the separation of photogenerated charge carriers. Furthermore, when the mass ratio of photocatalytic material to PDMS is 30 : 1, the photocatalytic superhydrophobic coating exhibits optimal performance, attaining a contact angle of 159.55° and NO degradation rate of 70.9%. The study also found that the photocatalytic superhydrophobic coating remained stable after undergoing cyclic degradation, acid and alkali resistance tests, and self-cleaning tests. The mechanism of photocatalytic superhydrophobic coatings was further explored, which provided new insights and a theoretical foundation for the development of self-cleaning urban environments.