A novel step-scheme BiVO4/Ag3VO4 photocatalyst for enhanced photocatalytic degradation activity under visible light irradiation  

梯型BiVO4/Ag3VO4光催化剂的构建及其可见光光催化性能

作　　者：Lizhong Liu Taiping Hu Kai Dai Jinfeng Zhang Changhao Liang 刘丽忠;胡太平;代凯;张金锋;梁长浩(淮北师范大学绿色和精准合成化学及应用教育部重点实验室,物理与电子信息学院,安徽淮北235000;中国科学院固体物理研究所,材料物理重点实验室和安徽纳米材料和纳米技术重点实验室,安徽合肥230031)

机构地区：[1]Key Laboratory of Green and Precise Synthetic Chemistry and Applications,Ministry of Education,College of Physics and Electronic Information,Huaibei Normal University,Huaibei 235000,Anhui,China [2]Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology,Institute of Solid State Physics,Hefei Institute of Physical Science,Chinese Academy of Sciences,Hefei 230031,Anhui,China

出　　处：《Chinese Journal of Catalysis》2021年第1期46-55,共10页催化学报（英文）

基　　金：国家自然科学基金(51572103,51973078);安徽省杰出青年基金(1808085J14);安徽省教育厅重点项目(KJ2019A0595).

摘　　要：Over the past few years,the emission of organic pollutants into the environment has increased tremendously.Therefore,various photocatalysts have been developed for the degradation of organic pollutants.In this study,a step-scheme BiVO4/Ag3VO4 composite was synthesized via a hydrothermal and chemical deposition process for the degradation of methylene blue.The composite showed strong redox ability under visible light.The 40%BiVO4/Ag3VO4 composite showed excellent photocatalytic degradation properties with a Kapp of 0.05588 min^–1,which is 22.76 and 1.76 times higher than those of BiVO4(0.00247 min^–1)and Ag3VO4(0.03167 min^–1),respectively.The composite showed a stable performance and could retain 90%of its photocatalytic activity even after four cycles.The improved catalytic performance of the composite as compared to BiVO4 and Ag3VO4 can be attributed to its novel step-scheme mechanism,which facilitated the separation of the photogenerated charges and increased their lifetime.The photoluminescence measurement results and transient photocurrent response revealed that the composite showed efficient extraction of charge carriers.近年来,有机污染物的问题变得越来越严重.为了解决该问题,人们研究和开发了许多有效的光催化剂.本工作采用水热法和化学沉积法合成了BiVO4/Ag3VO4梯型半导体材料,该复合材料在可见光下具有很强的氧化还原能力.其中40%BiVO4/Ag3VO4具有最佳的光催化降解性能,其降解速率为0.05588 min^-1,分别是BiVO4和Ag3VO4的22.76和1.76倍.并且其性能稳定,经过四次循环后其降解率仍可保持90%以上.BiVO4和Ag3VO4复合后,其催化性能得到增强,归因于形成了新型的梯型光催化机制,该方法促进了光生电荷的分离并延长了电荷的寿命,且通过PL测试和瞬态光电流响应证明了电荷的有效转移.X射线衍射(XRD)可以观察到Ag3VO4和BiVO4物相,没有其他成分.用扫描电子显微镜(SEM)和透射电子显微镜(TEM)进一步观察了该催化剂的结构和形貌,从SEM可以看出,Ag3VO4生长在BiVO4的上面,能谱分析也证明该催化剂仅包含Ag3VO4和BiVO4的各种元素,而不含其他杂质,TEM进一步证明了两种物质复合在一起,而不是机械混合.通过紫外-可见光漫反射光谱(UV-vis)测试可以得到BiVO4和Ag3VO4的吸收带边,进一步计算BiVO4的带隙和导带分别为2.41和0.455 eV,Ag3VO4的带隙和导带分别为2.20和0.04 eV,二者组成的异质结的带隙满足降解的条件.用荧光光谱(PL)和光电流研究了样品的光电特征,结果表明BiVO4/Ag3VO4光催化剂具有很高的载流子分离效率和很低的光电流电阻,这有助于光生载流子的运输.光催化降解甲基蓝实验表明,BiVO4/Ag3VO4具有很强的光催化降解速率(0.05588 min^-1),是BiVO4的22.6倍,Ag3VO4的1.76倍,而且经过四次循环后仍能保持很高的活性.通过XRD发现使用后的催化剂并没有发生变化,说明该催化剂具有良好的稳定性.高分辨X射线光电子能谱(XPS)不仅进一步说明了该催化剂成功复合后没有其他杂质元素,而且从各元素的结合能变化可以看出构成异质�

关 键 词：Step-scheme photocatalyst BIVO4 Ag3VO4 Photocatalytic activity Methylene blue 

分 类 号：X703[环境科学与工程—环境工程] O643.36[理学—物理化学] O644.1[理学—化学]