采用简易水热法在聚乙二醇-6000 (PEG-6000)辅助下合成了Ag3PO4多面体.系统考察了水热反应温度、时间及PEG-6000用量对产物形貌和结构的影响.通过X射线衍射(XRD),扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-Vis DRS)和荧光(PL)光谱等测试手段对光催化剂进行了表征.结果表明,适宜的水热温度及PEG-6000用量是制备具有{110}活性晶面取向Ag3PO4多面体的必要条件,该多面体通过纳米颗粒的Ostwald熟化效应生长而成.可见光催化降解罗丹明B (RhB)的实验表明,该Ag3PO4多面体活性明显优于其它水热条件下所制备的非{110}取向晶面样品和离子交换法所得纳米颗粒,其降解反应速率常数(k)为离子交换法所得Ag3PO4纳米颗粒的8.3倍.总有机碳含量(TOC)及循环实验证明,该Ag3PO4多面体可以有效地矿化RhB并保持较好的循环稳定性.活性自由基捕获实验表明,空穴(h+)和羟基自由基(·OH)是光催化氧化的主要活性物种.结合活性物种的氧化还原电位以及Ag3PO4的能带结构分析,提出了催化反应界面光生电子-空穴(e--h+)对的分离及转移机制. Ag3PO4 polyhedrons were synthesized by a facile hydrothermal route using polyethylene glycol-6000 (PEG-6000). The effects of hydrothermal temperature, reaction time, and PEG-6000 dosage on the morphologies and structures of the products were systematically investigated. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), and photoluminescence (PL) spectra. The hydrothermal temperature and the PEG dosage are key factors in the production of Ag3PO4 polyhedrons with oriented {110} facets. The Ag3PO4 polyhedrons evolve via Ostwald ripening, and exhibit superior visible-light photocatalytic degradation of Rhodamine B (RhB) relative to Ag3PO4 samples without oriented {110} facets and Ag3PO4 nanoparticles prepared by anion-exchange. The reaction rate constant of the Ag3PO4 polyhedrons was 8.3 times that of the Ag3PO4 nanoparticles. Total organic carbon (TOC) analysis and cycling experiments revealed that the polyhedrons have better mineralization efficiency and exhibit good circulation runs. Holes (h+) and hydroxyl radicals (·OH) are confirmed to be the dominant active species in the presence of radical scavengers and in N2-saturated solution. Given the redox potential of the active species and the band structure of Ag3PO4 polyhedron, the separation and migration mechanism of photogenerated electron-hole (e--h+) pairs at the photocatalytic interface was proposed
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