催化学报

催化学报 ›› 2017, Vol. 38 ›› Issue (12): 2120-2131.DOI: 10.1016/S1872-2067(17)62959-0

• 论文 • 上一篇    下一篇

基于CuxO电子转移助剂及TiO2价带边调控的协同效应驱动可见光催化

孔丽娜a, 张昕彤b, 王长华b, 万方旭b, 李岚a   

  1. a 天津理工大学材料科学与工程学院, 材料物理研究所, 显示材料与光电器件教育部重点实验室, 天津市光电显示材料与器件重点实验室, 天津 300191;
    b 东北师范大学物理学院, 先进光电子功能材料研究中心, 紫外光发射材料与技术教育部重点实验室, 吉林长春 130024
  • 收稿日期:2017-10-10 修回日期:2017-10-31 出版日期:2017-12-18 发布日期:2017-12-29
  • 通讯作者: 张昕彤, 李岚
  • 基金资助:

    国家自然科学基金（51072032，51372036，51702235）.

Synergic effects of CuxO electron transfer co-catalyst and valence band edge control over TiO2 for efficient visible-light photocatalysis

Lina Konga, Xintong Zhangb, Changhua Wangb, Fangxu Wanb, Lan Lia   

  1. a Institute of Material Physics, Key Laboratory for Optoelectronic Materials and Devices of Tianjin, Key Laboratory of Display Materials and Photoelectric Devices of Ministry of Education, College of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300191, China;
    b Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, China
  • Received:2017-10-10 Revised:2017-10-31 Online:2017-12-18 Published:2017-12-29
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (51072032, 51372036, 51702235).

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摘要：

TiO2基光催化剂迈向实际应用的关键在于更加有效地分离电荷和拓宽光吸收范围至可见光区域.通过担载助剂促进光生电荷分离以及掺杂调控能带、提高可见光吸收是实现高性能光催化剂的两个重要途径.在众多助剂中，廉价、无毒且催化性能优异的过渡金属氧化物（如Co-，Ni-，Cu-和Fe-氧化物）助剂在光催化降解污染物、水分解、CO2还原等领域尤其引人关注.而氧缺陷作为氧化物的固有缺陷，可实现TiO2的能带调控，提升可见光吸收性能.其中，常见的缺氧缺陷是通过导带边调控来拓宽可见光吸收范围，但其光生电子还原能力降低.因TiO2价带空穴具有足够强的氧化能力，本文拟通过在TiO2中引入富氧缺陷调控价带边及担载电子转移助催化剂的途径研制高效可见响应型光催化剂.
本文利用超声喷雾热解过氧钛酸和湿化学浸渍法制备了CuxO负载富氧型TiO2微球.采用扫描电子显微镜（SEM），透射电子显微镜（TEM），N2吸附-脱附等温曲线，X射线衍射（XRD），X射线光电子能谱（XPS），紫外可见漫反射光谱（UV-Vis-DRS）等手段对CuxO负载富氧型TiO2微球的结构特征和光谱吸收性质进行系统研究.SEM，TEM和N2吸附/脱附等温曲线结果表明，CuxO负载富氧型TiO2微球是纳米颗粒紧凑堆叠的介孔微球，直径为200-2000 nm，Cu元素高度均匀分散于微球上.XRD和XPS分析表明，富氧缺陷TiO2微球相比参照TiO2微球具有更大的晶格参数，同时晶体中具有大量的过氧物种（Ti-O-O），证明了过氧缺陷的存在.UV-Vis-DRS和XPS的价带谱验证，富氧缺陷使得TiO2价带顶上移，提高了可见光吸收性能.鲁米诺化学发光（CL）探针实验进一步证明，表面负载的CuxO助剂将表面吸附氧高效还原为活性氧物种（O2·-和H2O2），提高了光生电子利用率.因此，CuxO负载富氧型TiO2微球表现出更快的可见光催化降解乙醛速率，分别为富氧型TiO2、非富氧型TiO2和CuxO-TiO2的8.6、13.0和11.0倍.并且，CuxO负载富氧型TiO2微球在可见光催化降解乙醛的五次循环实验中，活性基本保持不变.CuxO负载富氧型TiO2微球在模拟太阳光和UV光辐照下光催化降解乙醛速率相比富氧型TiO2微球也大幅提升，分别提升4.6和2.7倍.CuxO负载富氧型TiO2微球光催化性能增强归因于富氧缺陷和CuxO电子转移助催化剂的协同作用.其中，富氧缺陷使得TiO2价带边上移，拓宽可见光吸收范围，CuxO电子转移助剂引入界面电荷转移和多电子氧还原过程，加速光生电子利用率，促进光生电荷分离.该策略也为开发其他高效异质结光催化剂提供参考.

关键词: 可见光催化, TiO2, CuxO助催化剂, 富氧缺陷, 介孔微球

Abstract:

Bandgap engineering by doping and co-catalyst loading are two primary approaches to designing efficient photocatalysts by promoting visible-light absorption and charge separation, respectively. Shifting of the TiO2 conduction band edge is frequently applied to increase visible-light absorption but also lowers the reductive properties of photo-excited electrons. Herein, we report a visible-light-driven photocatalyst based on valance band edge control induced by oxygen excess defects and modification with a CuxO electron transfer co-catalyst. The CuxO grafted oxygen-rich TiO2 microspheres were prepared by ultrasonic spray pyrolysis of the peroxotitanate precursor followed by a wet chemical impregnated treatment. We found that oxygen excess defects in TiO2 shifted the valence band maximum upward and improved the visible-light absorption. The CuxO grafted onto the surface acted as a co-catalyst that efficiently reduced oxygen molecules to active intermediates (i.e., O2·-radial and H2O2), thus consuming the photo-generated electrons. Consequently, the CuxO grafted oxygen-rich TiO2 microspheres achieved a photocatalytic activity respectively 8.6, 13.0 and 11.0 as times high as those of oxygen-rich TiO2, normal TiO2 and CuxO grafted TiO2, for degradation of gaseous acetaldehyde under visible-light irradiation. Our results suggest that high visible-light photocatalytic efficiency can be achieved by combining oxygen excess defects to improve visible-light absorption together with a CuxO electron transfer co-catalyst. These findings provide a new approach to developing efficient heterojunction photocatalysts.

Key words: Visible light photocatalysis, TiO2, CuxO cocatalyst, Oxygen-excess defect, Porous microsphere