BiOAc BiOX(X=Cl,Br)复合材料的制备及其对混合染料的去除

Synthesis of BiOAc BiOX(X=Cl,Br)Composites for Removal of Mixed Dyes

铋系半导体光催化剂虽然光响应范围广、催化性能稳定,但光生电子和空穴复合率高、光催化效率低,形成二元异质结是解决该问题的有效途径.该研究在室温下,采用化学沉淀法制备花球状BiOAc,然后通过离子交换法与BiOX(X=Cl, Br)复合形成BiOAc/BiOX二元异质结光催化材料.利用XRD、SEM、TEM、N_(2)吸附解吸等温线、UV-vis DRS、EIS等技术表征材料的晶体结构、光学性质及光生载流子复合情况.以阳离子混合染料[罗丹明B(RhB)、亚甲基蓝(MB)]和阴离子混合染料[靛红(Isatin)、达旦黄(Titan yellow)]作为目标污染物评定样品的光催化性能及重复使用性;通过捕获试验对BiOAc/BiOX光催化体系中的反应活性物种进行检测,并对光催化机理进行了推测.结果表明:(1)通过离子交换过程,BiOAc和BiOX成功地复合在一起形成异质结结构.(2)BiOAc与BiOX的摩尔比为6∶1时,复合材料具有最佳的光催化性能.(3)BiOAc/BiOBr比BiOAc/BiOCl对阳离子染料的吸附能力更强,有利于染料的光催化降解.(4)重复试验表明该方法合成的BiOAc/BiOX复合材料具有较好的稳定性.(5)光催化反应过程中起主要作用的活性物种是·O_(2)^(-)和h^(+),光生电子在BiOAc和BiOX导带间的传输抑制了电子空穴对的复合,提高了光催化效率.以上研究结果表明,该BiOAc/BiOX复合材料在染料废水的深度处理方面具有潜在的应用前景.

Bi-based materials have attracted much attention due to their broad light response and stable photocatalytic properties.However,their high recombination rate of photoinduced electron-hole pairs and low photocatalytic efficiency remain common drawbacks.The fabrication of heterojunction materials has proven to be an efficient strategy for the resolution of these issues.Herein,flower-shaped BiOAc was synthesized by chemical precipitation at room temperature.Subsequently,BiOAc BiOX(X=Cl,Br)composite materials were synthesized through ion exchange between BiOAc and BiOX.The crystalline structures and optical properties of the materials,as well as the recombination of photoinduced carriers were characterized by XRD,SEM,TEM,N_(2) adsorption and desorption isotherm,UV-vis DRS,and EIS.Mixed cationic dyes(rhodamine B(RhB)and methylene blue(MB))and anionic dyes(Isatin and Titan yellow)were selected as target pollutants to evaluate the photocatalytic performance and stability of the samples.In addition,trapping experiments were conducted to detect the reactive species in the BiOAc BiOX photocatalytic system,and the possible functional mechanism was proposed.Conclusions were obtained as the following:(1)A BiOAc BiOX heterojunction was formed through the ion-exchange process.(2)When the molar ratio of BiOAc to BiOX was 6∶1,the best photocatalytic performance was obtained.(3)The BiOAc BiOBr exhibited a stronger adsorption capacity for cationic dyes than BiOAc BiOCl,which facilitated the photocatalytic degradation of the pollutants.(4)Cycling experiments revealed that the prepared BiOAc BiOX composites had excellent photocatalytic stability.(5)The main species in the photocatalytic reaction were·O_(2)^(-)and h^(+).The transfer of photoinduced electrons between the BiOAc and BiOX conduction bands inhibited the recombination of electron-hole pairs,thus improving the photocatalytic activities.The research results suggested that the prepared materials had strong potential for advanced treatment of dye wastewater.