Synthesis,Characterization And Photocatalytic Performance Of BiOCl-based Photocatalysts

BiOCl has attracted considerable attention because of its unique layered-structure,fascinating physicochemical properties as well as chemical and optical stability.However,the wide band-gap energy and low utilization efficiency of solar energy limits its wide application.Thus,the improvement of the visible-light harvest and photocatalytic performance under visible-light irradiation is essential for the wide application of BiOCl.In this paper,the photocatalytic performance of BiOCl under visible-light irradiation was enhanced through crystal facet control,in-situ heterojunction construction and dehalogenation method.Meanwhile,the photocatalytic mechanism was comprehensively investigated.BiOCl with exposed（001）facet was synthesized via a facile hydrothermal route,and the（001）facet exposure percentage control was realized by adjusting the amount of solution water.The microstructures of samples were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,UV-Vis diffuse reflectance spectroscopy（UV-Vis）,etc.The results indicated that the thickness of BiOCl nanoplates decreased and the facet exposure percentage increased with an increase of the amount of solvent.The RhB and CIP were chosen as a model reaction to evaluate the photocatalytic performances of various samples.As a result,BiOCI with higher facet exposure percentage showed superior photocatalytic activity than the counterpart with lower facet exposure percentage,which is attributed to that the more the（001）facet expose,the higher the photogenerated electrons and holes separate.Using BiOCl as precursor,the Bi₂₄O₃₁Cl₁₀/BiOCl heterojuction was constructed through a simple thermal annealing method.The compositions and morphologies of samples were characterized by XRD,TEM,UV-vis,X-ray photoelectron spectroscopy（XPS）,etc.The results indicated that BiOCl microspheres gradually transformed to square sheets Bi₂₄O₃₁Cl₁₀ with increasing the annealing temperature.The obtained Bi₂₄O₃₁Cl₁₀/BiOCl heterojunction displayed excellent photocatalytic efficiency and selectivity toward the conversion of benzyl alcohol to benzaldehyde under visible light irradiation,which could reach 40.3%and>99%,respectively.The in-situ generation of heterojunction photocataly may provide superior interfacial contact,which is advantageous for enhancing the photocatalytic performance.Non-stoichiometric bismuth oxyhalide Bi₁₂O₁₇Cl₂ was successfully synthesized by hydrothermal method through controlling the pH value in the presence of various surfactants.The structures and morphologies of samples were characterized by XRD,SEM,UV-Vis,etc.The results indicated that the participation of surfactants not only enhanced the BET value,but also induced the morphology transformation and band-gap energy regulation.The photocatalytic activities of products were evaluated by decomposing RhB and O-Chlorophenel under visible light irradiation.The results indicated that the photocatalytic activity of product in the presence of surfactant was higher than the counterpart in the absence of surfactant.This phenomenon is possibly related to that the presence of surfactant could induce higher specific surface area and more active sites,which are beneficial for the enhancement of photocatalytic performance.