Defect-engineering of Pt/Bi4NbO8Br heterostructures for synergetic promotional photocatalytic removal of versatile organic contaminants

Abstract

A strategy to improve its photocatalytic performance is still a challenge for the novel Sillen–Aurivillius perovskite type Bi₄NbO₈Br. Herein, novel Pt modified Bi₄NbO₈Br composites (Pt/BNB) with sufficient oxygen vacancies were successfully fabricated via a facile in situ chemical reduction method. For one thing, the deposition of Pt nanoparticles brings about a Mott–Schottky effect at the interface to accept photo-induced electrons, leading to an efficient charge separation. For another thing, the electronic metal–support interaction of Pt and Bi₄NbO₈Br decreases the formation energy of oxygen defects, which could serve as active sites for O₂ activation. On account of the synergetic effect of Pt and oxygen vacancies, the dominant active species-photogenerated holes are accumulated on the surface of the photocatalysts, while the additional superoxide radicals are also involved. Hence, Pt/BNB performed with excellent photocatalytic activities in the degradation of wastewater contaminants, and the kinetic rate was 4.64, 10.21, 5.53, 9.80, 1.71 and 4.05 times, respectively, those of pristine Bi₄NbO₈Br towards methyl orange, rhodamine B, 2,4-dichlorophenol, p-nitrophenol, ciprofloxacin and tetracycline hydrochloride.