王磊,韩浩,朱凌甫,彭猛,康健,王德生,许嘉钰.BiOCl/TiO2的氯化改性及其新式光生自由基催化反应[J].环境科学学报,2021,41(7):2758-2765
BiOCl/TiO2的氯化改性及其新式光生自由基催化反应
- The new free radical reaction of chlorinated BiOCl/TiO2
- 基金项目：国家大气攻关项目（No.DQGG0302-04）
- 王磊
- 1. 清华大学, 环境学院, 北京 100084;2. 防化研究院, 国民核生化灾害防护国家重点实验室, 北京 102205
- 韩浩
- 防化研究院, 国民核生化灾害防护国家重点实验室, 北京 102205
- 朱凌甫
- 北京化工大学, 化学工程学院, 北京 100029
- 康健
- 防化研究院, 国民核生化灾害防护国家重点实验室, 北京 102205
- 王德生
- 防化研究院, 国民核生化灾害防护国家重点实验室, 北京 102205
- 摘要：采用溶胶凝胶法制备了BiOCl/TiO2复合催化剂，透射电镜（TEM）照片显示，两种半导体分布均匀、相互连接，形成的异质结可以为电子传导提供有效通道.经过氯化处理的复合材料具备更强的光催化能力，在紫外光条件下对苯的降解率达到90%，是原BiOCl/TiO2的2倍、纯TiO2的10倍.本文利用X射线光电子能谱、红外光谱和电子顺磁共振，对表面氯化的机理进行研究.结果表明，氯元素以Ti—Cl的方式吸附在催化剂表面，在光照条件下光生空穴夺取一个电子，使其生成氯自由基，进而配合超氧、羟基，构成一种新型的三自由基光催化体系，使催化降解能力大幅提升.最后，利用实验方法得到了光生氯自由基的直接证据，并构建了该体系的光催化反应机理.
- Abstract：In this article, the BiOCl/TiO2 composite has been successfully prepared via a sol-gel method and then modified by surface chlorination. According to the TEM images, two components were uniformly dispersed and connected to each other, which facilitated the transfer of photo-generated carriers. Under the UV light irradiation, the BiOCl/TiO2 exhibited good photocatalytic activity and stability for gas-phase benzene oxidation and the surface chlorination would further enhance its performance. About 90% degradation was achieved over chlorinated BiOCl/TiO2, which was twice as original BiOCl/TiO2 and ten times compared to bare TiO2. The prepared composites have been characterized by electronic chemistry station, Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) to explore the outstanding photocatalytic activity. As confirmed by XPS and FT-IR, the Cl was chemically adsorbed on the surface of catalyst (Ti-Cl), which would lead to a new mechanism for photocatalysis. Under the UV light irradiation, besides ·OH and ·O2- radicals, the photocatalytic reaction was also driven by photo-generated ·Cl radicals, which was confirmed by EPR analysis. Hence, the photocatalytic activity was significantly enhanced by synergistic effects of three radicals.
