Synthesis And Visible-Light Photocatalytic Performance Of Bismuth Oxyhalides Materials

A large amount of organic dyes in textile and other industrial effluents are produced annually around the world.Environmental experts point out that increasing pollution not only cause serious problems such as global warming but also could threaten to end human life on our planet.In order to eliminate the pollution,considerable efforts have been made to develop photocatalysts.As a traditional photocatalyst,TiO₂ has been the most popular and gained much progress because of its numerous applications,such as in H2 production through water splitting,depuration of waste water or air,and decomposition of organic pollutant.However,TiO₂ with its wide band gap energy of 3.2 eV that can only be excited by ultraviolet radiation?accounting for just 4% of the sunlight?,which limited the practical application.The modification of TiO₂ or exploitation of novel effective photocatalysts that can be excited by visible light is a matter of great urgency in current photocatalysis research.As a group of V–VI–VII semiconductors,bismuth oxyhalides?BiOX,X = Cl,Br,I?with tetragonal matlockite structure have been drawn much attention,it can be used as remarkable photocatalysts due to their unique excellent electrical and optical properties.So we need to develop a simple method to synthesis BiOX?X=Cl,Br,I?nanomaterials which exhibit a high degradation rate,high stability and easy separation for recycling use.In this paper,we constructed a series of BiOX nanomaterials through a solvothermal method.The influence of reaction condition on morphology and photocatalysis efficiency will be investigated in detail.The idiographic work is as follows:?1?Well-crystallized square-like bismuth oxychloride?BiOCl?nanosheets with tunable thickness were successfully prepared by a simple hydrothermal method without adding any additives.The as-obtained products were characterized by X-ray powder diffraction?XRD?,scanning electron microscopy?SEM?,selected area electron diffraction?SAED?,high resolution transmission electron microscopy?HRTEM?,N2adsorption–desorption and UV–Vis diffuse reflectance spectroscopy?DRS?techniques.RhB can be mineralized under either UV light or visible light.Notably,the BiOCl nanosheets photocatalysts not only had good reusable property but also retained high photocatalytic stability after several cycles.?2?Hierarchical BiOBr microspheres were successfully synthesized via a solvothermal method byusing the diethylene glycol?DEG?as the solvent and soft-template.The formation mechanism for the growth of hierarchical BiOBr microspheres has been studied.The possible mechanism of photocatalysis has been discussed systematacially.Remarkably,the as-prepared BiOBr microspheres have a large specific surface area,which can reach a maximum surface area of 55.93 m 2 /g.In addition,the superior enhanced photocatalytic activities of BiOBr microspheres were evaluated by the photodegradation of methyl orange?MO?and Rhodamine B?RhB?under visible-light illumination,which presented the efficiency up to98.10% just within 50 min and 98.64% within 30 min,respectively.BiOBr microspheres can be a promising candidate as highly efficient photocatalyst for decompositing of organic contaminants for environmental remediation.?3?The boll-like sphere BiOI were fabricated via a facile solvothermal approach with the assistance of polyvinylpyrrolidone?PVP?.The effect of the quality of PVP and different molar ratios of I to Bi on phase,morphology and degradation rate of the as-prepared products were discussed in detail.The possible photocatalytic mechanism has been investigated based on the quenching experiment.The photocatalytic activities of the boll-like sphere BiOI are evaluated on the degradation of MO,MB and RhB.The results further demonstrated that the boll-like sphere BiOI possessed high photocatalytic activity,can open new possibilities for the treatment organics and pollutants in water by solar irradiation.