Optimization of Fenton-like reaction pathways using Ov-containing ZnO@nitrogen-rich porous carbon: the electron transfer and 1O2 triggered non-radical process†

Abstract

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 (O_v) 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 ¹O₂ but also provided access for electron transfer. Meanwhile, O_v sites increased electron density and electron migration strength, which promoted more electron transfer from O_vs 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 O_v to regulate the occurrence of non-radical pathways, which could provide a strategy to control the PDS reaction pathway.