蕨草状氧化铋/碳纸柔性复合物的原位制备及其增强的光催化活性

In-situ Preparation of Flexible Fern-Like Bi_(2)O_(3)/Carbon Paper Composite with Enhanced Photocatalytic Activity

氧化铋(Bi_(2)O_(3))是一种重要的可见光光催化剂,在光催化降解有机污染物、污水处理方面有较大的应用潜力。然而,Bi_(2)O_(3)比表面积较低、其光生电子与空穴复合快等缺点都导致其光催化性能较差,严重制约了其应用。同时,Bi_(2)O_(3)的粉末形态不利于回收利用,也使其应用受到较大的限制。为此,以柔性导电碳纸作基底,采用电化学沉积和后续原位氧化的方法,制备了柔性Bi_(2)O_(3)/碳纸复合光催化剂,以提高其光催化性能和操作便利性。制备的复合物中,具有蕨草状分级结构的β-Bi_(2)O_(3)牢固地长在碳纸基底上。在可见光光催化分解水中苯酚的反应中,Bi_(2)O_(3)/碳纸复合物的光催化性能不仅明显优于无分级结构的α-Bi_(2)O_(3)粉体,还优于有一定分级结构的β-Bi_(2)O_(3)。结合N2吸附、紫外可见漫反射光谱、荧光和自由基测试等测试分析,发现Bi_(2)O_(3)/碳纸复合光催化剂的性能提升源于Bi_(2)O_(3)的分级结构和导电碳纸的电子捕获作用。分级结构有利于Bi_(2)O_(3)的光吸收和与反应物的接触,而碳纸的电荷捕获作用能有效分离Bi_(2)O_(3)的光生电子和空穴,从而共同促进光生载流子的有效利用。此外,复合光催化剂所具有的宏观尺度、柔性和二维形貌等特征也使其使用和回收变得更为方便。本研究为柔性分级结构光催化剂的设计提供了一个新的思路。

Bismuth oxide(Bi_(2)O_(3)) is an important visible-light-driven photocatalyst, which possesses an application potential in photocatalytic degradation of organic pollutants and treatment of wastewater. However, low specific surface area and rapid recombination of carriers lead to a poor photocatalytic performance of Bi_(2)O_(3), seriously restricting its application. Besides, the particle morphology of Bi_(2)O_(3)is also not conducive to recycling and application. In this work, a flexible Bi_(2)O_(3)/carbon paper composite photocatalyst was prepared via electrochemical deposition and subsequent in-situ oxidation to improve its photocatalytic performance and operation convenience. In the as-prepared composite photocatalysts, fern-like β-Bi_(2)O_(3)with a hierarchical structure is grown on the carbon paper substrate. In the visible-light-driven photocatalytic degradation of phenol in water, the photocatalytic performance of Bi_(2)O_(3)/carbon paper composite can surpasses α-Bi_(2)O_(3)powder without a hierarchical structure and precedes the β-Bi_(2)O_(3)with a hierarchical structure. Based on the analysis of N_(2) adsorption, diffuse reflection spectra,photoluminescence and reactive radical, the improved activity of Bi_(2)O_(3)/carbon paper composite is ascribed to the fern-like hierarchical structure of Bi_(2)O_(3)and the electron capturing role of conductive carbon paper. The hierarchical structure favors the light absorption of Bi_(2)O_(3)and its contact with reactants, while the electron capturing role of carbon paper can effectively separate the photogenerated electrons and holes in Bi_(2)O_(3), thus promoting the utilization of carriers. In addition, the macro-size, flexibility and two-dimensional morphology of the composite also make the operation and recycling more convenient. This study provides an effective strategy for the design of flexible photocatalysts with a hierarchical structure.