煅烧温度对花朵状钨酸铋光催化活性的影响

钨酸铋在水相体系中能光催化降解有机污染物,而对于钨酸铋光催化活性影响因素的研究非常少.本文研究了煅烧温度对花朵状钨酸铋光催化活性的影响.以钨酸钠和硝酸铋为原料,在160°C下水热反应20 h,合成催化剂,并经不同温度煅烧3 h.用X射线衍射(XRD)、拉曼(Raman)光谱、紫外-可见漫反射吸收光谱(UVVis DRS)和荧光(PL)光谱表征样品.结果表明,这些样品具有十分相似的相组成和电子结构.然而,对于水中苯酚的降解,钨酸铋的光催化活性显示出了很大的差异.钨酸铋的光催化活性随着煅烧温度的升高,先上升后下降,最优煅烧温度为350°C,并且不受样品比表面积大小的影响.这些样品的活性差异主要归结于钨酸铋的结晶度、吸光性和表面缺陷对其光生载流子分离效率的综合影响.

Effect of Sintering Temperature on the Photocatalytic Activity of Flower-Like Bi2WO6

Bi₂WO₆ is reportedly active for the photocatalytic degradation of organic compounds in aerated aqueous solution, but factors influencing the photocatalytic activity of pristine Bi₂WO₆ have received little attention. In this study, the effect of sintering temperature on the physical properties of flower-like Bi₂WO₆ was investigated. The catalyst was synthesized through the hydrothermal reaction of Na₂WO₄ and Bi(NO₃)₃ at 160 ℃ for 20 h, followed by sintering in air at different temperatures for 3 h. Bi₂WO₆ samples were characterized with X-ray diffraction, scanning electron microscopy, and Raman, ultraviolet-visible diffuse reflectance, and photoluminescence spectroscopies. All samples had similar phase compositions and electronic structures. Samples exhibited different activities for the photocatalytic degradation of phenol in aerated aqueous solution, under ultraviolet light. With increasing Bi₂WO₆ sintering temperature, the rate of phenol degradation first increased and then decreased. The maximum rate of phenol degradation was observed from the catalyst sintered at 350 ℃. Similar results were obtained when the rate of phenol degradation was normalized with the specific surface area of the catalyst, as determined by N2 adsorption. The observed sintering temperature-dependent photoactivity of Bi₂WO₆ was attributed to a combination of its crystallinity, light absorption, and surface defects.