Oxygen vacancy-induced nonradical degradation of nitroso-containing organics in Fe3O4@NC electro-Fenton reaction at a wide pH range

In this work, Fe 3 O 4 -anchored nitrogen-doped carbon catalyst (Fe 3 O 4 @N–C) with abundant oxygen vacancies (V o ) and mesoporous structure was successfully synthesized for electro-Fenton (EF) catalytic process. The catalyst demonstrated impressive degradation efficiency towards nitroso-containing organics due to the superior electronic transfer of N–C skeleton and V o , making it easier for the electron-deficient –NO 2 groups to adsorb on the catalyst surface and oxidize rapidly. Typically, the degradation efficiency of p-nitrophenol (PNP) reached 95.6 % in natural pH. Notably, the catalyst exhibited excellent performance over a wide pH range (3 ∼ 11), and has strong anti-interference performance against anions and natural organic matter in water matrix. Mechanism analysis indicated that V o could promote the formation of highly active electron-rich Fe(II) species, and promote the activation of H 2 O 2 and O 2 as additional active sites, thus, a large amount of ·OH and O 2 ·- would be produced and then quickly converted into 1 O 2 . As a result, 1 O 2 is the main reactive species for PNP degradation in Fe 3 O 4 @N–C electro-Fenton reaction. The results will provide insights into the design of high-performance catalysts for the selective oxidation of organic pollutants in wastewater.