Tip engineering of carbon nanotubes to navigate the activation pathway of peroxymonosulfate for adaptive pollutant removal

The customization of radical and nonradical species in advanced oxidation processes (AOPs) is recognized for its potential to selectively eliminate micropollutants with varying redox potentials from complex wastewater matrices. However, the precise and facile design of catalytic centers featuring optimal electronic configurations poses a significant challenge. Herein, we introduce a tip engineering approach to produce cleaved carbon nanotubes (CNTs) with modulated chain lengths via an eco-friendly and straightforward ball milling process. The resultant CNTs, featuring C,O-enriched tips, demonstrate a substantial enhancement in phenol (PhOH) degradation efficiency upon peroxymonosulfate (PMS) activation, achieving approximately a 2.4-fold increase. Notably, the proportion of radical species (i.e., •OH and SO 4 •− ) generated is tunable across a broad spectrum from 41 % to 84 % by regulating the abundance of high-spin edge C sites through altering the ball milling time. Additionally, the nonradical oxidation of PhOH is facilitated by surface-adsorbed PMS (*PMS) on the basal carbon sites. The practical applicability of this hybrid radical/nonradical reaction system has been further substantiated through its successful deployment in the removal of pollutants with diverse redox potentials within a pressure-driven membrane filtration setup. Our findings proffer a promising avenue for active site engineering to modulate catalytic performance, offering valuable insights for the development of carbonaceous Fenton-like catalysts.