多级结构形貌β-Bi2O3/BiOCOOH复合光催化剂的制备及其光催化性能

Preparation and Photocatalytic Properties of Composite Photocatalyst β-Bi2O3/BiOCOOH with Hierarchical Structure

用水热法合成具有多级结构形貌的甲酸氧铋,将其作为自牺牲前驱体调节热处理温度制备出不同的产物,其中一种是具有可见光响应的新型β-Bi2O3/BiOCOOH复合光催化材料。使用X射线衍射(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)、扫描电子显微镜(SEM)和光电化学响应等手段表征不同温度热处理后产物的晶型结构、光吸收性能、形貌、光电流等物理化学性质。以罗丹明B作为光催化活性评价的探针分子,研究了在不同温度热处理产物的可见光光催化性能。结果表明,热处理温度从250℃提高到330℃、400℃、450℃,甲酸氧铋发生以下转变:BiOCOOH→β-Bi2O3/BiOCOOH→β-Bi2O3→α-Bi2O3。在330℃和350℃热处理后的β-Bi2O3/BiOCOOH复合光催化剂可见光催化性能最优,其降解速率比β-Bi2O3、α-Bi2O3分别高6.7倍和100倍。对罗丹明B表现出最佳脱色率的样品,光照90 min的矿化率可达88%。与纯相物质(β-Bi2O3、BiOCOOH)相比β-Bi2O3/BiOCOOH复合材料具有更大的光电流响应和更小的阻抗。结合UV-vis DRS和莫特-肖特基曲线可推测,β-Bi2O3与BiOCOOH可紧密结合形成Z-型光催化结构,具有更高的光生载流子分离效率并实现光生电荷的分离。

The BiOCOOH with multi-layered structure was synthesized by hydrothermal method,and then was used as sacrificial precursor to prepare several different products through adjusting heat treatment temperatures, including a new type of composite photocatalytic material β-Bi2 O3/BiOCOOH with visible light response. The crystal structure, optical absorption performance, morphology, photocurrent and other physical and chemical properties of the products were characterized by means of X-ray diffraction(XRD), UV-Vis DRS, scanning electron microscope(SEM), photoelectric chemical response and other characterization methods. Their photocatalytic activity was assessed via degradation test of Rhodamine B solution. The results show that when the heat treatment temperature gradually increased from250℃ to 330℃, 400℃ and 450℃, the following transformation occurred: BiOCOOH→β-Bi2 O3/BiOCOOH→β-Bi2 O3→α-Bi2 O3. The visible light catalytic performance of the composite photocatalyst β-Bi2 O3/BiOCOOH is the best. The degradation rate of Rhodamine B in the presence of β-Bi2 O3/BiOCOOH composite photocatalyst was 6.7 times and 100 times higher than those in the presence of β-Bi2 O3 and α-Bi2 O3, respectively. The samples that showed the best decolorization rate for rhodamine B had a mineralization rate of 88% within 90 minutes of illumination. Electrochemical test results show that the composite β-Bi2 O3/BiOCOOH has a larger photocurrent response and a smaller impedance than the plain materials β-Bi2 O3 and BiOCOOH. In addition, by considering both of UV-Vis DRS and Mott-Shottky curves comprehensively, the positions of conduction and valence bands of β-Bi2 O3 and BiOCOOH can be estimated respectively, and it is speculated that β-Bi2 O3 and BiOCOOH can be closely combined to form z-type photocatalytic structure, thus having higher separation efficiency of photogenerated carriers and effective separation of photogenerated charges.