Diesel soot photooxidation enhances the heterogeneous formation of H2SO4

• Published in: Nature communications Vol. 13; no. 1; p. 5364
• Main Authors: Zhang, Peng, Chen, Tianzeng, Ma, Qingxin, Chu, Biwu, Wang, Yonghong, Mu, Yujing, Yu, Yunbo, He, Hong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 12.09.2022; Nature Publishing Group UK; Nature Portfolio
• Subjects: Black carbon; Carbon; Catalytic oxidation; Conversion; Diesel; Free radicals; Irradiation; Light irradiation; Oxidation; Photochemicals; Photooxidation; Radiation; Soot; Sulfur dioxide; Sulfuric acid
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-33120-3

Abstract Both field observation and experimental simulation have implied that black carbon or soot plays a remarkable role in the catalytic oxidation of SO 2 for the formation of atmospheric sulfate. However, the catalytic mechanism remains ambiguous, especially that under light irradiation. Here we systematically investigate the heterogeneous conversion of SO 2 on diesel soot or black carbon (DBC) under light irradiation. The experimental results show that the presence of DBC under light irradiation can significantly promote the heterogeneous conversion of SO 2 to H 2 SO 4 , mainly through the heterogeneous reaction between SO 2 and photo-induced OH radicals. The detected photo-chemical behaviors on DBC suggest that OH radical formation is closely related to the abstraction and transfer of electrons in DBC and the formation of reactive superoxide radical (•O 2 − ) as an intermediate. Our results extend the known sources of atmospheric H 2 SO 4 and provide insight into the internal photochemical oxidation mechanism of SO 2 on DBC.