Enhanced Fenton-like process via interfacial electron donating of pollutants over in situ Cobalt-doped graphitic carbon nitride

The heterogeneous Fenton process suffers from low efficiency because of the low electron transfer cycle rate of Fe3+/Fe2+, which often consumes enormous amounts of hydrogen peroxide (H2O2) or other energy. Herein, we report a novel Co-based Fenton-like catalyst (in-situ-Co-g-C3N4) synthesized via the surface complexation method, in which Co species were modified in situ into the framework of the graphitic carbon nitride (g-C3N4) substrate through C-O-Co chemical bonding. The catalyst exhibited higher Fenton-like catalytic activity than pure g-C3N4 in the degradation of various pollutants under neutral conditions, as evidenced by the approximately 150-fold higher Fenton-like reaction rate constant of in-situ-Co-g-C3N4 than that of g-C3N4. Density functional theory (DFT) calculations and a series of experimental and characterization analyses revealed the interfacial reaction mechanism between H2O2, pollutants and in-situ-Co-g-C3N4. During the Fenton-like reaction, the electron-poor C center on the aromatic ring of g-C3N4 could capture the electrons deprived from pollutants, and subsequently deliver them to around the electron-rich Co center to efficiently reduce H2O2 to hydroxyl radicals (•OH), enabling H2O2 to be used efficiently for the degradation of pollutants. This study provides a strategy for improving Fenton-like degradation efficiency by effectively utilizing the energy of organic pollutants.