| Photocatalytic technique as a promising and green technology, has great potential in theenvironmental remediation field by using the solar energy. A prerequisite for the development ofphotocatalysis application is to obtain excellent photocatalysts. However, there are manydisadvantages as follows: firstly, TiO2is undoubtedly one of the most excellent and widely usedphotocatalyst due to its abundance, chemical stability, low cost, and nontoxicity. But a majordrawback of TiO2is its large bandgap (~3.2eV) and thus only UV light (typically λ<400nm; asmall fraction of solar spectrum,~4%) can be absorbed, which significantly limits the utilizationof solar light in the visible region. Secondly, the rapid recombination of photogeneratedelectron-hole pairs severely hinders the photocatalytic activity of the photocatalyst. Thirdly, thenano-photocatalysts are difficult to recycle, which will cause waste and secondary pollution.Hence, the development of photocatalysts with a broad range of visible-light response, excellentphotocatalytic activity, high photostability, and easily recycling is the key to the photocatalyticapplication. Given these, by using electrospinning-calcination method, we report the design andpreparation of Fe2O3-AgBr nonwoven cloth photocatalyst. Besides, the photocatalyticperformance of the photocatalyst for the degradation of rhodamine B (RhB) andparachlorophenol (4-CP) has also been studied. The major findings are as follows:(1) Fe2O3-AgBr nonwoven cloth was prepared by an electrospinning-calcination method. Byoptimizing conditions of electrospinnin technique, concentrations and viscosity of the solution, theFe2O3-AgBr nonwoven cloth with best photocatalytic performance was chosen. Such macroscalecloth is free-standing and it consists of hierarchical pores with diameters of600-750nm andnanofibers with diameters of150-350nm. Furthermore, these nanofibers are constructed fromFe2O3and AgBr nanoparticles with diameters of~60nm. In addition, Fe2O3-AgBr nonwovencloth has great photoabsorption from UV region to visible-light region and magnetic property. (2) When the rhodamine B (RhB) as the target pollutant, the Fe2O3-AgBr nonwoven clothcould phtodegrade91.8%RhB after60min visible light irradiation. Fe2O3-AgBr nonwoven clothexhibits higher photocatalytic activity than Fe2O3nonwoven cloth and AgBr nonwoven clothcontaining the same weight of visible-light-active component. Besides, the photocatalyst showsthe highest photocatalytic activity when the pH of RhB is neutral. The photocatalytic activitybecomes lower with the increasing of the RhB concentration. Therefore, the reasons of the highphotocatalytic activity of Fe2O3-AgBr nonwoven cloth have been analyzed. One reason is thebroadening of photoabsorption of the photocatalyst. The other reason is the energy level matchingbetween Fe2O3semiconductor and AgBr semiconductor. Fe2O3-AgBr nonwoven cloth can beeasily transferred and/or recycled by diping/pulling method and/or external magnetic field, and ithas excellent photocatalytic stability during four times recycling tests.(3) When the parachlorophenol (4-CP) as the target pollutant, the Fe2O3-AgBr nonwovencloth could phtodegrade74.2%4-CP after120min visible light irradiation. Fe2O3-AgBrnonwoven cloth exhibits higher photocatalytic activity than Fe2O3nonwoven cloth and AgBrnonwoven cloth containing the same weight of visible-light-active component. Besides, thephotocatalyst shows the highest photocatalytic activity when the pH of RhB is neutral.4-CP notonly can be degraded, but only can be mineralized. After4h visible light irradiation,70.7%4-CPcan be mineralized. The intermediate products could be detected via gas chromatography-massspectrography (GC-MS) method. Hence, Fe2O3-AgBr nonwoven cloth are proved to be a excellentvisible-light photocatalyst. |
PDF Full Text Request