Li Xinwei, Li Haiwei, Huang Yu, Cao Junji, Huang Tingting, Li Rong, Zhang Qian, Lee Shun-Cheng, Ho Wingkei
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China; The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, China.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China; The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, China; Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CIC-AEET), School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China.
J Hazard Mater. 2022 Feb 15;424(Pt A):127217. doi: 10.1016/j.jhazmat.2021.127217. Epub 2021 Sep 14.
To understand the conversion mechanism of photocatalytic gaseous formaldehyde (HCHO) degradation, strontium (Sr)-doped TiO-OV catalysts was designed and synthesized in this study, with comparable HCHO removal performance. Our results proved that foreign-element doping reduced Ti to the lower oxidation state Ti, and that the internal charge kinetics was largely facilitated by the unbalanced electron distribution. Oxygen vacancies (OVs) were developed spontaneously to realize an electron-localized phenomenon in TiO-OV, thereby boosting O adsorption and activation for the enhanced generation of reactive oxygen species (ROS). At the chemisorption stage, in-situ DRIFTS spectra and density functional theory calculation results revealed that surface adsorbed O (O) and lattice O (O) engaged in the isomerisation of HCHO to dioxymethylene (DOM) on TiO-OV and TiO, respectively. Time-resolved DRIFTS spectra under light irradiation revealed that the DOM was then converted to formate and thoroughly oxidized to CO and HO in TiO-OV. While bicarbonate byproducts were detected from DOM hydroxylation or possible side conversion of CO in TiO, owing to insufficient consumption of surface hydroxyl. Our study enhances the understanding on the photocatalytic oxidation of HCHO, thereby promoting the practical application in indoor air purification.
为了解光催化气态甲醛（HCHO）降解的转化机制，本研究设计并合成了具有可比HCHO去除性能的掺锶（Sr）TiO-OV催化剂。我们的结果证明，外来元素掺杂将Ti还原为较低氧化态的Ti，并且内部电荷动力学在很大程度上由不平衡的电子分布促进。氧空位（OVs）自发形成，在TiO-OV中实现电子局域化现象，从而促进O的吸附和活化，以增强活性氧物种（ROS）的产生。在化学吸附阶段，原位漫反射红外傅里叶变换光谱（DRIFTS）和密度泛函理论计算结果表明，表面吸附的O（O）和晶格O（O）分别在TiO-OV和TiO上参与HCHO异构化为二氧亚甲基（DOM）。光照下的时间分辨DRIFTS光谱表明，DOM随后在TiO-OV中转化为甲酸盐并完全氧化为CO和HO。而在TiO中，由于表面羟基消耗不足，从DOM羟基化或CO可能的副反应中检测到碳酸氢盐副产物。我们的研究增进了对HCHO光催化氧化的理解，从而推动其在室内空气净化中的实际应用。
