Hierarchical BiOX (X=Cl, Br, I) microrods derived from Bismuth-MOFs: In situ synthesis, photocatalytic activity and mechanism

Abstract

As an important kind of visible-light driven photocatalysts for wastewater treatment without secondary pollution, bismuth oxyhalides (BiOX, X = Cl, Br, I) are typically synthesized by the solvothermal method in sealed autoclaves, which presents many limitations for practical application. In this work, a series of hierarchical BiOX (X = Cl, Br, I) microsheets were first prepared by the facile halogenation process of a new bismuth metal–organic frameworks (Bi-BTC), and the Bi-BTC acts as the bismuth source and the frame of the hierarchical structure. Morphological analysis shows that three BiOX samples are constructed by many BiOX microsheets and exhibit a rod-like overall morphology. In addition to X-ray diffraction and photoelectron spectroscopy, other characterizations, including systematic optical and electrochemical measurements, were carried out for a better understanding of the three BiOX photocatalysts. Rhodamine B degradation experiments driven by visible light reveal the good photocatalytic activities and mineralization performance of BiOX, and BiOCl exhibits the best removal performance. In subsequent pH condition and reuse tests, BiOX shows good adaptability at a wide pH range and high reuse efficiency in four reuse cycles. The energy band structure and radical analysis prove that superoxide and photo-induced holes are the main functional radicals in the three photocatalytic systems.