文献类型：期刊文献

英文题名：Persistent Free Radicals on Carbon Nanotubes and Their Catalytic Effect on Benzoyl Peroxide Decomposition

作者：Xu, Xiang[1]; Yang, You[1]; Guan, Yong[1]; Wei, Dafu[1]; Zheng, Anna[1]

机构：[1] Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, 200237, China

年份：2022

外文期刊名：SSRN

收录：EI(收录号：20220121795)

语种：英文

外文关键词：Benzoic acid - Catalysis - Catalytic oxidation - Computational chemistry - Electron transitions - Electronic structure - Ethanol - Free radical reactions - Free radicals - Graphene - Nanotubes - Organic solvents - Oxygen - Paramagnetic resonance - Quantum chemistry - Ultraviolet spectroscopy

摘要：Carbon nanotubes (CNTs) are attracting considerable attention as environmental catalysts and antioxidants owing to their dual properties of generating and scavenging reactive oxygen species. However, the electron-transfer mechanism of CNTs remains unclear. In this study, CNTs were found to exhibit a remarkable catalytic effect on the decomposition of benzoyl peroxide (BPO) in ethanol at room temperature. The catalytic mechanism was investigated through a combination of experiments and quantum chemical calculations. The catalytic effects of five carbonaceous materials—single-walled CNTs (SWCNTs), multi-walled CNTs (MWCNTs), graphene, graphite, and graphene oxide (GO)—were investigated by UV spectroscopy. BPO was found to rapidly decompose into benzoic acid in SWCNT– and MWCNT–ethanol systems but remain stable in the graphite– and GO–ethanol systems. The catalytic performance of the MWCNTs was significantly affected by the polarity and pH of the solvent. In particular, BPO hardly decomposed in the MWCNT–hexane and MWCNT–ethanol/HCl systems. Electron paramagnetic resonance spectroscopy was employed to characterize the persistent free radicals (PFRs) on the CNTs, which helped establish the free-radical pathway as the route for the catalytic decomposition of BPO. Quantum chemistry calculations, including spin-density distributions and computational electrochemistry, indicated that the PFRs were essentially aryloxy radicals dispersed on the aromatic ring. Polycyclic aromatic hydrocarbons with larger π-conjugated structures and more aryloxy radicals exhibited a stronger electron-transfer ability. Finally, the mechanism of CNTs operating as electron acceptors and donors was elucidated, and a pathway for electron transfer between CNTs, BPO, and ethanol was proposed. ? 2022, The Authors. All rights reserved.