Optimization of Fenton-like reaction pathways using Ov-containing ZnO@nitrogen-rich porous carbon: the electron transfer and 1O2triggered non-radical processElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4en00749b

With the development of persulfate-based Fenton-like catalysis, how to control the PDS reaction pathway is a great challenge. Herein, we prepared catalysts with nitrogen-rich porous carbon (NPC) layers and oxygen vacancy (Ov) sites for PDS activation to degrade sulfamethazine (SMZ). Results revealed that the ZnO@NPC/PDS system exhibited only non-radical pathways, which comprised the singlet oxygen (1O2) and electron transfer process. The intrinsic mechanism underlying the production of active species was further verified by comparing the results of the ZnO@NPC/PDS and ZnO@NPC-Etch/PDS systems, Raman analysis and DFT calculations. Adsorption of PDS by carbon layers resulted in the formation of a catalyst–PDS complex, which not only elongated the S–O bond and accelerated the decomposition of PDS to generate 1O2but also provided access for electron transfer. Meanwhile, Ovsites increased electron density and electron migration strength, which promoted more electron transfer from Ovs to PDS molecules through nitrogen-rich porous carbon layers. Moreover, the ZnO@NPC/PDS system could maintain a degradation rate of >90% for SMZ in real water matrixes. T. E. S. T software prediction and toxicity tests were used to investigate environmental implications of degradation intermediates, which showed reduced ecological toxicity compared with SMZ. This work fabricated the ZnO@NPC/PDS system and explored the interaction between nitrogen-rich porous carbon layers and Ovto regulate the occurrence of non-radical pathways, which could provide a strategy to control the PDS reaction pathway.