Efficient photocatalytic degradation of bisphenol A and dye pollutants over BiOI/Zn2SnO4 heterojunction photocatalyst

Abstract

BiOI/Zn₂SnO₄ composites with a heterostructure have been synthesized via a chemical deposition method under mild conditions by tuning the BiOI mass ratios. The physicochemical characteristics were investigated by X-ray diffraction (XRD), diffuse reflectance ultraviolet-visible light spectroscopy (DRS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The XRD results show that two phases of BiOI and Zn₂SnO₄ co-existed in the composites. The HRTEM image showing clear lattice fringes proves the formation of a heterojunction at the interfaces of BiOI and Zn₂SnO₄. The photocatalytic degradation of the endocrine disruptor bisphenol A and dyes (MB and RhB) indicated that the BiOI/Zn₂SnO₄ composites were more photoactive than pure BiOI and Zn₂SnO₄. The activity enhancement was mainly ascribed to the formation of a heterojunction between BiOI and Zn₂SnO₄, which facilitated the transfer and separation of photogenerated electron–hole pairs. The photoelectrochemical measurement has also confirmed the enhancement of the separation efficiency of electron–hole pairs.