Potential Difference Driving Electron Transfer via Defective Carbon Nanotubes toward Selective Oxidation of Organic Micropollutants

Abstract

Nanocarbon-based persulfate oxidation emerges as a promising technology for the elimination of organic micropollutants (OMPs). However, the nature of the active site and its working mechanism remain elusive, impeding developments of high-performance oxidative technology for water treatment practice. Here, we report that defect-rich carbon nanotubes (CNTs) exhibit a superior activity in the activation of peroxymonosulfate (PMS) for OMP oxidation. Quantitative structure-activity relationship studies combined with theoretical calculations unveil that the double-vacancy defect on CNTs may be the intrinsic active site, which works as a conductive bridge to facilitate the potential difference-dominated electron transfer from the highest occupied molecular orbital of OMPs to the lowest unoccupied molecular orbital of PMS. Based on this unique mechanism, the established CNTs@PMS oxidative system achieves outstanding selectivity and realizes the target-oriented elimination of specific OMPs in a complicated aquatic environment. This work sheds new light on the mechanism of carbocatalysis for selective oxidation and develops an innovative technology toward remediation of practical wastewater.