催化学报 ›› 2020, Vol. 41 ›› Issue (4): 710-718.DOI: 10.1016/S1872-2067(19)63472-8

• 论文 • 上一篇    下一篇

SrTiO3/BiOI异质结构:界面电荷分离、增强光催化活性和反应机理

陈瑞敏a, 王红a, 武慧中a, 盛建平b, 李解元b,c, 崔雯b,d, 董帆a,b   

  1. a 重庆工商大学环境与资源学院, 重庆市催化与新环境材料重点实验室, 重庆 400067;
    b 电子科技大学基础与前沿科学研究院环境科学研究中心, 四川成都 611731;
    c 四川大学建筑与环境学院, 四川成都 610065;
    d 西南石油大学材料科学与工程学院, 新能源材料与技术中心, 四川成都 610500
  • 收稿日期:2019-09-10 修回日期:2019-10-12 出版日期:2020-04-18 发布日期:2019-12-12
  • 通讯作者: 武慧中, 董帆
  • 基金资助:
    国家自然科学基金(21822601,21501016,21777011);国家重点研发计划(2016YFC02047);重庆市创新团队项目(CXTDG201602014);重庆市自然科学基金(cstc2017jcyjBX0052).

SrTiO3/BiOI heterostructure: Interfacial charge separation, enhanced photocatalytic activity, and reaction mechanism

Ruimin Chena, Hong Wanga, Huizhong Wua, Jianping Shengb, Jieyuan Lib,c, Wen Cuib,d, Fan Donga,b   

  1. a Chongqing Key Laboratory of Catalysis and New Environmental Materials, College of Environment and Resources, Chongqing Technology and Business University, Chongqing 400067, China;
    b Research Center for Environmental Science & Technology, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, China;
    c College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan, China;
    d The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500, Sichuan, China
  • Received:2019-09-10 Revised:2019-10-12 Online:2020-04-18 Published:2019-12-12
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21822601, 21501016, 21777011), the National R&D Program of China (2016YFC02047), the Innovative Research Team of Chongqing (CXTDG201602014), the Natural Science Foundation of Chongqing (cstc2017jcyjBX0052). The authors also acknowledge AM-HPC in Suzhou, China for computational support.

摘要: 异质结构光催化剂为实现高效的电荷分离,提高光催化性能提供了一种有效的途径.虽然宽禁带和窄禁带光催化剂已经得到了广泛的研究,但它们在接触界面上的电荷分离和转移规律尚未完全揭示.本文采用简便的方法成功地制备了一种新型SrTiO3/BiOI (STB)异质结构光催化剂.该光催化剂中的异质结构可以将光吸收扩展到可见光范围,从而在可见光照射下获得较高的光催化NO去除性能.实验和理论证据表明,BiOI光生电子可以通过预成型的电子传递通道直接转移到SrTiO3表面.
XRD和XPS结果表明,SrTO3/BiOI复合材料已成功制备.SEM和TEM图像显示了SrTiO3,BiOI和STB样品的形貌.能量色散X射线(EDX)元素图清楚地表明SrTiO3均匀分布在BiOI纳米片表面,证实BiOI与SrTiO3形成了界面.高分辨率XPS表明,电子从BiOI中Bi和I原子转移到STB化合物中SrTO3的Sr和Ti原子.采用DFT进一步确定了BiOI与SrTiO相互作用的机制.电子局域函数(ELF)表明,STB的接触界面存在共价相互作用.SrTiO3和BiOI之间生成的共价键导致局域化超额电子(e-ex)的积累.在可见光照射下,界面内的电子交换增强,从而提高反应物活化和ROS生成的效率.
采用自制的连续流反应体系,研究了在可见光照射下制备的样品对NO去除的光催化性能.与SrTiO3和BiOI相比,STB具有显著增强的可见光光催化活性,去除率为59.0%.UV-vis DRS显示,STB异质结的光吸收扩展到可见光范围.SrTiO3具有可见光活性,这归因于EPR所描述的氧空位的存在.随后计算态密度(DOS),发现氧空位可以形成缺陷能级,降低激发电子所需的光能.利用ESR光谱发现,STB上的ESR信号强度都要强得多,说明STB异质结具有较好的氧化能力,也说明光生载流子可以通过电子传递通道被有效地分离.原位红外光谱表明,在SrTiO3上,NO主要转化为NO2.STB的加速电荷分离和转移特性,促进活性氧的生成,从而进一步有效地将有毒中间体NO2转化为目标产物.
设计并制备的SrTiO3/BiOI异质结光催化剂在可见光辐照下净化空气中NO的效率提高,同时抑制了有毒中间体的生成.通过实验和理论相结合的方法揭示了在两种材料的接触界面上建立的电子传递通道.来自BiOI的光生电子可以通过预先形成的电子传递通道直接转移到SrTiO3表面,从而促进了ROS的生成,所以整体的NO纯化效率和对有毒中间体的抑制作用提高.综上,本文提出了一种简单、新颖的促进空气污染物高效安全净化的策略.

 

关键词: 异质结构, SrTiO3/BiOI, 电荷分离, 光催化, 反应机理

Abstract: Heterostructured photocatalysts provide an effective way to achieve enhanced photocatalytic performances through efficient charge separation. Although both wide- and narrow-band-gap photocatalysts have been widely investigated, the charge separation and transfer mechanism at the contacting interface of the two has not been fully revealed. Here, a novel SrTiO3/BiOI (STB) heterostructured photocatalyst was successfully fabricated by using a facile method. The heterostructure in the photocatalyst extends the photoabsorption to the visible light range, and thus, high photocatalytic NO removal performance can be achieved under visible light irradiation. A combination of experimental and theoretical evidences indicated that the photogenerated electrons from the BiOI semiconductor can directly transfer to the SrTiO3 surface through a preformed electron delivery channel. Enhanced electron transfer was expected between the SrTiO3 and BiOI surfaces under light irradiation, and leads to efficient ROS generation and thus a high NO conversion rate. Moreover, in situ diffused reflectance infrared Fourier transform spectroscopy revealed that STB can better inhibit the accumulation of the toxic intermediate NO2 and catalyze the NO oxidation more effectively. This work presents a new insight into the mechanism of the interfacial charge separation in heterostructures and provides a simple strategy to promote the photocatalytic technology for efficient and safe air purification.

Key words: Heterostructure, SrTiO3/BiOI, Charge separation, Photocatalysis, Reaction mechanism

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