Photocatalytic Oxidation of NO2 on TiO2: Evidence of a New Source of N2O5

作者：Biwu Chu, Yuan Liu, Hao Li, Yongcheng Jia, Jun Liu, Qing Cao, Tianzeng Chen, Peng Zhang, Qingxin Ma, Xiao Cheng Zeng, Joseph S. Francisco, Hong He · 发表于：Angewandte Chemie International Edition · 年份：2023 · DOI：10.1002/anie.202304017 · 被引用次数：16 · 研究领域：Air Quality Monitoring and Forecasting、Atmospheric chemistry and aerosols、Catalytic Processes in Materials Science

Abstract N 2 O 5 is an important intermediate in the atmospheric nitrogen cycle. Using a flow tube reactor, N 2 O 5 was found to be released from the TiO 2 surface during the photocatalytic oxidation of NO 2 , revealing a previously unreported source of N 2 O 5 . The rate of N 2 O 5 release from TiO 2 was dependent on the initial NO 2 concentration, relative humidity, O 2 /N 2 ratio, and irradiation intensity. Experimental evidence and quantum chemical calculations showed that NO 2 can react with the surface hydroxyl groups and the generated electron holes on the TiO 2 , followed by combining with another NO 2 molecule to form N 2 O 5 . The latter was physisorbed on TiO 2 and had a low adsorption energy of −0.13 eV. Box model simulations indicated that the new source of N 2 O 5 released from TiO 2 can increase the daytime N 2 O 5 concentration by up to 20 % in urban areas if abundant TiO 2 ‐containing materials and high NOx concentrations were present. This joint experimental/theoretical study not only demonstrates a new chemical mechanism for N 2 O 5 formation but also has important implications for air quality in urban areas.