Oxygen vacancies promote sulfur species accumulation on TiO2 mineral particles

作者：Shang, Huan; Wang, Xiao; Li, Hao; Li, Meiqi; Mao, Chengliang; Xing, Pan; Zhao, Shengxi; Chen, Ziyue; Sun, Jing; Ai, Zhihui^*; Zhang, Lizhi^*

来源：Applied Catalysis B: Environmental , 2021, 290: 120024.

DOI：10.1016/j.apcatb.2021.120024

• Heterogeneous reaction of SO2
• Sulfate aerosol
• TiO2 mineral
• Photochemistry
• Oxygen vacancy

In this study, we investigated the heterogeneous SO2 oxidation catalyzed by defective TiO2 mineral particles at molecular scale. Theoretical DFT calculations revealed that O-2 favorably attached to oxygen vacancies, while SO2 adsorption more likely took place over the unsaturated Ti-5c and O-2c or hydroxyl sites of TiO2 bearing surface oxygen vacancies (TiO2-OV). In the dark, the amount of sulfite species formed on TiO2-OV surface via the SO2 adsorption was 8 times that on pristine TiO2 due to the increased charges of the undercoordinated Ti and O sites around OVs. Although solar light irradiation could promote the sulfate accumulation on both pristine TiO2 and TiO2-OV, OVs facilitated molecular oxygen activation to generate center dot O-2(-) capable of photochemically converting interfacial SO2, accounting for higher sulfate accumulation of TiO2-OV than that of pristine TiO2. These findings provide in-depth understanding of sulfur species identification and sulfate aerosol formation on defective metal oxide minerals in atmosphere.

• 单位
  中国科学院