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Bi OBr为受热不稳定的半导体。研究了煅烧温度、时间和气氛对Bi OBr结晶度、表面羟基和相变影响。然后考察了催化剂结构变化对可见光催化降解染料酸性橙Ⅱ的活性影响。利用X射线衍射、扫描电镜、紫外可见漫反射光谱、红外光谱等对不同煅烧条件处理后的Bi OBr样品进行了结构、形貌等分析。结果表明,空气气氛下,500℃以下的煅烧处理,可以明显提高Bi OBr的结晶度和光催化活性;在煅烧温度高于520℃时,Bi OBr发生Bi OBr→Bi24O31Br10的转变,在600~650℃煅烧,可产生Bi OBr/Bi24O31Br10混合相,大幅度提高可见光催化活性;在750℃煅烧生成的α-Bi2O3虽然具有较好的可光吸收性能,但是颗粒发生烧结,可见光活性很低。真空气氛煅烧虽然可以提高结晶度,但易导致表面脱羟基,不利于光催化活性的大幅度提高。
Bi OBr is a thermally unstable semiconductor. The effects of calcination temperature, time and atmosphere on the crystallinity, surface hydroxyl groups and phase transition of Bi OBr were investigated. Then, the effect of the structure of the catalyst on the activity of visible light photocatalytic degradation of acid orange Ⅱ was investigated. The structure and morphology of Bi OBr samples after different calcination conditions were analyzed by X-ray diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy and infrared spectroscopy. The results show that the crystallinity and photocatalytic activity of Bi OBr can be obviously improved under calcination temperature below 500 ℃ in air atmosphere. When the calcination temperature is above 520 ℃, the transformation of Bi OBr → Bi 24 O 31 Br 10 occurs at 600 ~ 650 ℃ Calcined to produce Bi OBr / Bi24O31Br10 mixed phase, which can greatly increase the visible light catalytic activity. Although the α-Bi2O3 calcined at 750 ℃ has good absorbability, the particles are sintered and the visible light activity is very low. Vacuum atmosphere calcination can improve the crystallinity, but easily lead to the surface of hydroxyl, is not conducive to a substantial increase in photocatalytic activity.