催化学报 ›› 2025, Vol. 74: 130-143.DOI: 10.1016/S1872-2067(25)64649-3

• 论文 • 上一篇    下一篇

溴氧铋表面氧空位调控压电性质用于提升光催化CO2还原反应效率与产物选择性

李存军a, 何杰b, 蔡天乐b, 陈贤雷a,*(), 陶亨聪c, 周英棠c,*(), 朱明山b,*()   

  1. a浙江海洋大学海洋科技学院国家海洋水产养殖工程技术研究中心浙江省石油化工环境污染控制重点实验室, 浙江舟山 316004
    b暨南大学环境与气候学院, 广东广州 511443
    c浙江海洋大学海洋科学与技术学院, 浙江舟山 316004

Surface oxygen vacancies of BiOBr regulating piezoelectricity for enhancing efficiency and selectivity of photocatalytic CO2 reduction

Cunjun Lia, Jie Heb, Tianle Caib, Xianlei Chena,*(), Hengcong Taoc, Yingtang Zhouc,*(), Mingshan Zhub,*()   

  1. aZhejiang Key Laboratory of Petrochemical Environmental Pollution Control, National Engineering Research Center for Marine Aquaculture, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan 316004, Zhejiang, China
    bGuangdong Key Laboratory of Environmental Pollution and Health, College of Environment and Climate, Jinan University, Guangzhou 511443, Guangdong, China
    cMarine Science and Technology College, Zhejiang Ocean University, Zhoushan 316004, Zhejiang, China
  • Received:2025-01-07 Accepted:2025-02-24 Online:2025-07-18 Published:2025-07-20
  • Contact: *E-mail: zschenxl@163.com (X. Chen), zhouyingtang@zjou.edu.cn (Y. Zhou), zhumingshan@jnu.edu.cn (M. Zhu).
  • Supported by:
    National Natural Science Foundation of China(22322604)

摘要:

光催化CO2还原作为一种先进的CO2转化技术, 能够利用取之不尽的太阳能将CO2转化为高附加值的化学燃料, 不仅可以降低大气中CO2的整体浓度, 还可以缓解全球能源危机问题. 目前, 许多半导体光催化剂已被开发并应用于光催化CO2还原领域. 其中, 溴氧化铋(BiOBr)作为一种层状三元氧卤化物半导体, 因其出色的光催化活性而广受关注. BiOBr的层状结构可以为催化反应提供丰富的活性位点, 也很容易制造缺陷来改变分子结构并增强光吸收. 然而, 目前关于缺陷工程的研究大多集中在BiOBr材料的晶面调控、提高光吸收性能和捕获载流子等领域, 对于与缺陷状态改变晶体结构相关的压电特性经常被忽视. 在非中心对称的晶体结构中, 往往具有由偶极矩产生的压电极化效应, 这为提高光催化反应活性提供了另一种可靠的策略.

基于此, 本文报道了一种富含氧空位(OVs)的溴氧铋(BOB-OV)材料, 其压电性能可受OVs含量调控. 与不含OVs的BOB相比, 这种含有OVs的BOB-OV可以在超声振动应力的作用下提升光催化CO2还原的效率, 实现稳定高效的CO2光还原过程, 并可高选择性地生成CO. 首先通过调控煅烧时间合成了一批具有不同OVs含量的BOB-OV材料, 电镜表征结果表明, BOB-OV呈现不规则堆叠纳米片状结构, 而通过不同刻蚀深度的X射线光电子能谱得知, OVs主要存在于BOB-OV的表面. 拉曼光谱显示不同的OVs浓度会改变BOB-OV中Bi-Br键的拉伸程度, 从而产生强的偶极矩, 加上氧原子的缺失改变了BOB-OV层状结构的对称性, 这表明OVs的引入赋予了BOB-OV强的压电极化性质. 压电力显微镜(PFM)结果表明, OVs的浓度并非越高越好, 具有适中OVs浓度的BOB-OV-2的压电响应最强. 在光催化CO2还原性能测试中发现, OVs的引入对于BOB材料进行单纯光催化CO2还原的性能提升并不显著, 但在外加超声应力的作用下进行压电协同光催化CO2还原, CO的产率提升能达到2倍以上. 其中, 压电响应最强的BOB-OV-2在外加应力的作用下也展现出最好的CO2光还原性能, CO的产率能够达到108.7 µmol g−1, 选择性高达92%. 原位开尔文探针力显微镜结果显示, BOB-OV-2在光照和暗条件下的接触电位差值能高达50 mV, 远高于BOB的10 mV, 这证明BOB-OV-2的强压电性质可在光催化反应过程中产生内建极化电场促进载流子迁移与分离. 而密度泛函理论计算也表明, BOB-OV材料中Bi原子是局域电子富集中心, 其与CO2分子的相互作用决定了整个催化CO2还原转化的过程. 适中的OVs浓度可以有效地吸附CO2并解吸产物CO, 证明BOB-OV-2具有最优的光催化CO2还原活性, 而施加2 GPa的压力比起无压力状态下更容易降低CO2吸附能垒和生成决速步骤产物*COOH的能垒, 表明外加应力可以提升光催化CO2还原活性和产物CO的选择性. 此外, 超声应力的引入还可以提供交变力场以屏蔽去极化场, 从而维持高效的光生电荷分离.

综上所述, 本文通过调控OVs含量赋予了BOB材料强的压电性质, 并将其应用在压电增强光催化CO2还原反应, 实现了高效的CO2还原和高CO产物选择性. 本工作为缺陷工程调控光催化剂的压电性质从而提升CO2光还原的效率和选择性提供了新的思路与见解.

关键词: 溴氧铋, 氧空位, 压电性质, 高选择性, 光催化CO2还原

Abstract:

Although defect engineering has been widely used to boost catalytic CO2 photoreduction, the piezoelectric polarized properties induced by structure changes through introducing defects are always ignored. Here we report a new kind of bismuth oxybromide (BiOBr, BOB) with piezoelectric property regulated by oxygen vacancies (OVs). Compared with pure BOB, BOB with OVs (BOB-OV) could enhance photocatalytic CO2 reduction efficiency under the ultrasonic force, achieving durable CO2 reduction process to superior production rates of CO (54.4 µmol g-1 h-1) with a high selectivity (92%). Moderate OVs concentration changed the degree of Bi-Br stretching in the BOB-OV to produce strong dipole moments, which endowed BOB-OV with strong spontaneous piezoelectric polarization ability under external force. Ultrasonic piezoelectric effects were innovatively integrated into the photocatalytic reaction, which not only provided an alternating force field to modulate the spontaneous polarization of BOB-OV, thereby maintaining efficient photogenerated charge separation, but also lowered the reaction energy barrier of CO2 by high stress, ultimately improving CO product selectivity. This study is the first to leverage OVs-induced piezoelectric polarization effects to enhance the performance and product selectivity of photocatalytic CO2 reduction, providing new directions and insights for defect engineering to contribute to photocatalysis.

Key words: BiOBr, Oxygen vacancy, Piezoelectricity, High selectivity, Photocatlytic CO2 reduction