摘要
通过一步水热法分别合成了(BiO)_2CO_3和N掺杂(BiO)_2CO_3分级微球光催化剂,并将制备的催化剂应用于低浓度NO的净化.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和紫外可见漫反射光谱仪(UV-vis DRS)等表征手段对催化剂微结构进行表征分析.利用原位红外技术对样品可见光催化氧化NO的反应过程进行实时动态检测分析,结合电子自旋共振(ESR)对自由基的捕获结果,提出了其反应机理.结果表明,相较于纯(BiO)_2CO_3,N掺杂(BiO)_2CO_3的反应过程中生成了中间产物NO+,使得其反应路径与机理与纯(BiO)_2CO_3不同,且中间产物的存在提高了反应速率与效率.同时N原子原位取代(BiO)_2CO_3表面的O原子,改变了其表面结构,产生了更多氧缺陷作为活化NO的反应位点,提高了反应效率.本文对于光催化反应过程研究和光催化剂结构优化提供了新思路.
With the rapid development of industry, air pollution has become a focused issue worldwide. As one of the major air pollutants, nitric oxide （NO） would lead to serious atmospheric problems such as acid rain, haze, and photochemical smog. Photocatalysis, as a green and effective technology, has become one of the most promising technologies for solving air pollution problems. As one of the typical photocatalyst, （BiO）2CO3 consists of alternating layers of [Bi202]2＋ and CO23- groups and has good optical absorption property, emerging as an attractive photocatalyst. In this work, （BiO）2CO3 and in situ N-doped （BiO）2CO3 hierarchical microspheres were fabricated by a one-pot hydrothermal method and applied to photocatalytic NO removal. The as-prepared samples were characterized by XRD, SEM, TEM, XPS, UV-vis DRS, PL and ESR. The photocatalytic NO oxidation process was monitored by in situ DRIFTS. The results indicated that the addition of urea has significant impact on （BiO）2CO3. The changed exposed facet influenced the morphological structure, band gap has narrowed and electronic-hole recombination rate of the as-prepared N doped （BiO）2CO3 has decreased. There are a lot of reports on photocatalytic NO oxidation, and the photocatalytic reaction mechanism for NO purification has been proposed for some photocatalysts with .02 and .OH radicals as the main reactive species and nitrates as the final products. However, little is known about the reaction intermediates during photocatalysis. To reveal the reaction mechanism of photocatalytic NO oxidation, in situ DRIFTS investigation was applied to probe the reaction process. The photocatalytic NO oxidation mechanism was revealed based on the in situ DRIFTS and ESR results. With N doping, the reaction process and the free radicals which participated during the photocatalystic reaction process become different from the pure （BiO）2CO3 sample. For BOC, .02 is main active radical, but for NBOC, the active radical changed to .OH. A new intermediate of NO＋ was discovered during photocatalysis, which increased the efficiency of the reaction. Because of the N doping, the electronic structure of （BiO）2CO3 has been broken, which leads to the formation of more oxygen vacancy. The present work could provide new perspectives for advancing the photocatalysis efficiency, offer a new insight into the photocatalytic NO oxidation process and promote large-scale environmental applications of high-performance photocatalysts.
作者
董兴安
何文杰
王红
孙艳娟
董帆
吴忠标
DONG XingAn HE WenJie WANG Hong SUN YanJuan DONG Fan WU ZhongBiao(Chongqing Key Laboratory of Catalysis and New Functional Materials, College of Environment and Resources, Chongqing Business University, Chongqing 400067, China Key Laboratory of Polluted Environment Remediation and Ecological Health Zhejiang University, Hangzhou 310027, China Technology and of Ministry of Education, Department of Environmental Engineering)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2017年第22期2534-2543,共10页
Chinese Science Bulletin
基金
国家自然科学基金(51478070
21501016
51108487)
国家重点研发计划(2016YFC0204702)
重庆市高校环境与能源催化创新团队建设计划(CXTDG201602014)
重庆市青年拔尖人才项目和重庆市基础与前沿研究计划(cstc2016jcyj A0481)资助
关键词
N掺杂
碳酸氧铋
光催化
原位红外
反应机理
N doping, （BiO）2CO3, photocatalysis, in situ FT-IR, reaction mechanism
