Unexpected SO<sub>2</sub> Photooxidation on Quantum-Sized Carbon
Peng Zhang, Liang Wang, Huazhang Guo, Hao Li, Shuying Wang, Yulong Shan, Tianzeng Chen, Biwu Chu, Qingxin Ma, Yonghong Wang, Yunbo Yu, Minghong Wu, Joseph S. Francisco, Hong He
Abstract
Surface photochemistry of carbon quantum dots (CQD) under atmospheric conditions remains poorly understood. Here, we systematically investigate the photoreactivity of CQD in the presence of SO 2 and reveal that CQD photoageing and its interaction with SO 2 occur independently of O 2 . Through a combined experimental and theoretical approach, we demonstrate that these unexpected surface reactions are driven by unique energy transfer and photocatalytic processes induced by photoexcited CQD. Key reactive intermediates─photogenerated hole, hydroxyl radical, sulfite radical, and carbon-centered radical─are identified as critical drivers of CQD surface photooxidation. This discovery provides new insights into the unresolved atmospheric photochemistry of flame-formed fresh soot, advances our understanding of photocatalytic processes on synthetic nanosized carbon materials, and offers clues to the origins of sulfated carbonaceous chondrites in interstellar media.