甲苯是一种最常见的室内有毒挥发性有机物(VOCs),目前消除方法主要有吸附、催化燃烧和光催化氧化,其中光催化是一种最高效和经济可行的方法,能在较温和条件下将甲苯完全矿化为 CO2.作为研究最广泛的光催化剂, TiO2在应用中通常有锐钛矿(ATiO2)和金红石(RTiO2)两种物相,但单物相 TiO2的低量子产率和光生电子-空穴对的快速复合严重限制了它的应用.本文选择兼具锐钛矿和金红石两种物相的 P25为催化剂载体,通过负载少量 ZnO和构建多组分并具备多通道载流子分离功能的异质结以提高 TiO2基光催化剂的性能.
利用一步浸渍法制备了一系列 ZnO/P25复合光催化剂,考察了其光催化降解气相甲苯性能. X射线粉末衍射结果表明, ZnO/P25异质光催化剂是由 ATiO2, RTiO2和红锌矿三种物相结构组成.高分辨透射电镜结果表明, ZnO/P25具备三相异质结 ZnO(002)/ATiO2(101)/RTiO2(110).紫外可见光谱、荧光光谱和光电流表征结果表明, ZnO/P25所形成的三相异质结不但增强了光吸收能力,还实现了多通道电子/空穴分离.催化降解实验表明, ZnO/P25异质光催化剂能在室温紫外光辐射下将甲苯完全矿化为 CO2和 H2O.基于三相异质结和多通道光生电子-空穴对分离的形成及促进作用, ZnO/P25光催化活性和速率均明显高于 P25.本文报道的多通道载流子分离理念可为高效光催化剂设计和应用提供一种新思路.
The fabrication of multicomponent heterojunctions is an effective strategy to improve the perfor‐mance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic performance of ZnO/TiO2 composites by the formation of multichannel charge separated heterojunctions. ZnO/P25 composites were prepared by an incipient wetness impregna‐tion method, and applied for the photocatalytic destruction of gaseous toluene. The ZnO/P25 com‐posites consist of anatase TiO2 (ATiO2), rutile TiO2 (RTiO2) and hexagonal zincite structures. The parasitic phase of ZnO in P25 leads to the formation of ZnO(002)/ATiO2(101)/RTiO2(110) hetero‐junctions that exhibit enhanced light absorption and improved multichannel electron/hole separa‐tion. ZnO/P25 heterojunctions can completely oxidize toluene into CO2 and H2O under ultraviolet light irradiation at room temperature, and show enhanced photocatalytic activity in comparison with P25 owing to the efficient electron‐hole separation. Such a multichannel charge separated design strategy may provide new insight into the design of highly effective photocatalysts and their potential technological applications.
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