Preparation,Modification And Its Photocatalytic Properties Of BiOX(X=Cl、Br、I) Photocatalyst

As a new and environmentally friendly water treatment technology, photocatalysis has attracted world attention of many researchers due to its low energy consumption, the process is simple and easy to operate, and the entire reaction process does not generate new pollutants properties. However, the most commonly used TiO₂ photocatalyst has a wide energy gap, and cannot make most use of the sunlight because of the low quantum efficiency, which limits its application. Therefore, scholars tend to study how to improve the TiO₂ photocatalyst or to develop a new type of catalyst which can make use of the visible light. The study focuses on a new photocatalyst whose morphology is uniform and who can have the response to visible light.Bismuth oxyhalides（BiOX, X=Cl, Br, I） captures great interest as a kind of semiconductor-based photocatalyst due to their effective, high stability, cheap, good optical and some other environmental properties. In fact, only BiOI photocatalyst is response to visible light among BiOX（X=Cl、Br、I） according to λ= 1240/â–³Eg can calculate the light response of the excitation wavelength of 365 nm, respectively 425 nm and 670 nm. In the face of these defects, we have to seek feasible method to modify BiOX（X=Cl, Br） for enhancing light quantum efficiency, and photocatalytic activity under visible light.In this paper, BiOX photocatalyst was synthesized using hydrothermal synthesis method in the presence of ethylene glycol（EG） with Bismuth nitrate pentahydrate as bismuth source and KCl, CTAB, KI as the emission of Cl, Br, I source. BiOCl and BiOBr with visible light photocatalytic properties were synthesized through modified by different methods.The samples were characterized by UV-VIS, TEM, XRD, PL and XPS.The results showed it is a good way to reduce the band gap of BiOCl, and increase light absorption of BiOCl through Br doped.Results showed that BiOCl_xBr_1-x exhibited higher photocatalytic activity under visible light when synthesized under the optimal ratio of n（Cl）:n（Br）=1:3.BiOBr photocatalytic activity were improved by construting a new heterojunction photocatalysts BiOBr-Bi₂MoO₆. The catalyst synthesized under the conditions of n（Br）: n（Mo） = 1: 2 ratio exhibited good photocatalytic activity.What’s more,the effect of water fluid temperature,the amount of surfactant additive PVP on structure and performance of BiOI are discussed to find the optimal conditions prepareing BiOI hierarchical microspheres.The catalyst prepared when temperature is at 140 ℃, the amount of PVP is 0.15 g in the reactive liquid,molar ratio of I and Bi is 1:1 showed the best photocatalytic activity for the degradation of rhodamine B（RhB） under visible light.