Synthesis And Photocatalytic Performances Of BiOCl With Controlled Crystal Facets

Environment and energy problem are two difficult problems facing society today, semiconductor photocatalytic technology shows excellent application prospect in environmental pollution control and new energy development field. It’s the research focus in photocatalytic field to develop semiconductor photocatalysts with high efficiency and high stability. The effective control of exposed facets of semiconductor photocatalysts is an important strategy for enhancing their photocatalytic activity. In this paper, we study the synthesis and photocatalytic performances of BiOCl with controlled crystal facets. The main contents are as following:1. Thin BiOCl nanosheets with exposed(001) facets were synthesized via hydrothermal method by controlling the concentration of hydrochloric acid(HCl). The thickness of Bi OCl nanosheet with exposed(001) facets changes from 7-200 nm with the concentration of HCl increase, the thinnest Bi OCl nanosheet with thickness of 7-15 nm is obtained when the concentration of HCl added is 8 mmol/L. The photocatalytic activity of these thin nanosheets with exposed(001) facets enhances gradually with the thickness of nanosheets decrease, which is ascribed to the thinner Bi OCl nanosheets which have a relatively shorter distance for photoinduced electron-hole pairs to be fast separated along[001] orientation under the self-induced internal static electric fields.Moreover, the thin BiOCl nanosheets have large surface area, which leads to good adsorptive ability for dye RhB, and then enhance the photosensitization activity of BiOCl.2. One-dimensional BiOCl nanomaterials were synthesized via hydrothermal method using glucose as the structure-directing agent. The thin Bi OCl nanosheets with exposed(001) facets assemble along the [001]direction, which lead to the formation of one-dimensional BiOCl nanomaterials with exposed(110) crystal facets. One-dimensional BiOCl nanomaterials show obvious facets-dependent photocatalytic activity,Bi OCl nanosheets with exposed(001) crystal facets exhibit much higher photocatalytic activity than one-dimensional BiOCl nanomaterials with exposed(110) crystal facets. This work will offer a simple and effective method to design and synthesize semiconductor photocatalysts with controlled crystal facets.3. One-dimensional Bi OCl/Bi4O5Cl2 heterostructures was synthesized by calcining one-dimensional BiOCl nanomaterials with exposed(110) facets. The composition, structure, morphology and optical property of the products were characterized by XRD, SEM, TEM, TG,XPS and UV-Vis. Experimental results show that exposed cryatal facets and the formation of junctions play the key roles in the photocatalysis.When the loaded-Bi4O5Cl2 content in the BiOCl/Bi4O5Cl2 heterostructures is too few or many, the exposed crytal facets play the main role in the photocatalytic degradation for Rh B dye; When the loaded-Bi4O5Cl2 content in the BiOCl/Bi4O5Cl2 heterostructures is moderate, the heterojunctions play more important role than exposed cryatal facets in the photocatalysis. Photogenerated carriers trapping experiment of BiOCl/Bi4O5Cl2 heterostructures shows that h+ and ·O2-are the main active species in the degradation process.