Accelerated Photodegradation of Organic Pollutants over BiOBr/Protonated g-C3N4

Abstract

Interfacial engineering has emerged as an effective strategy to optimize the photocatalytic activity of heterojunctions. Herein, the interface between graphitic carbon nitride (g-C3N4) and BiOBr was readily regulated by a protonation treatment. The synthesized BiOBr/g-C3N4 heterojunctions were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results show that pretreating g-C3N4 in diluted HCl solution led to a partial protonation of g-C3N4, which ensured intimate contact and high dispersion of supported BiOBr without changing the surface area, bulk g-C3N4 structure, or visible light absorption. The abundant BiOBr/g-C3N4 interfaces remarkably improved the separation and transfer of photogenerated carriers, which produced more h+ and O2●− to accelerate the photocatalytic degradation of organic pollutants. The photocatalytic activities of the BiOBr/g-C3N4 heterojunctions were evaluated by the degradation of RhB under visible-light irradiation (λ ≥ 420 nm). The apparent reaction (pseudo-first-order) rate constant of BiOBr supported on partially protonated g-C3N4 (Bpg-C3N4-0.75) is ca. 3-fold higher than that of BiOBr supported on pristine g-C3N4 (Bg-C3N4), verifying interfacial engineering as an effective strategy to optimize the catalytic activity of heterojunctions.