Innovative asymmetric Co_SA-N-Ti₃C₂T_x catalysis: unleashing superoxide radicals for rapid self-coupling removal of...

The polymerization pathway of contaminants rivals the traditional mineralization pathway in water purification technologies. However, designing suitable oxidative environments to steer contaminants toward polymerization remains challenging. This study introduces a nitrogen-oxygen double coordination strategy to create an asymmetrical microenvironment for Co atoms on Ti₃C₂T_x MXenes, resulting in a novel Co-N₂O₃ microcellular structure that efficiently activates peroxymonosulfate. This unique activation capability led to the complete removal of various phenolic pollutants within 3 min, outperforming the representative Co single-atom catalysts reported in the past three years. Identifying and recognizing reactive oxygen species highlight the crucial role of ⋅O₂ ^-. The efficient pollutant removal occurs through a ⋅O₂ ^--mediated radical pathway, functioning as a self-coupling reaction rather than deep oxidation. Theoretical calculations demonstrate that the electron-rich pollutants transfer more electrons to the catalyst surface, inducing the reduction of dissolved oxygen to ⋅O₂ ^- in the Co-N₂O₃ microregion. In a practical continuous flow-through application, the system achieved 100 % acetaminophen removal efficiency in 6.5 h, with a hydraulic retention time of just 0.98 s. This study provides new insights into the previously underappreciated role of ⋅O₂ ^- in pollutant purification, offering a simple strategy for advancing aggregation removal technology in the field of wastewater treatment.