Enhanced Fenton-like efficiency by the synergistic effect of oxygen vacancies and organics adsorption on FeO-d-g-CN with Fe‒N complexation.

d-g-CN-Fe composites was prepared via a self-assembly and calcination process. According to measurements and density functional theory (DFT) computations, the complexation of iron and pyridinic N of g-CN (Fe‒N) occurred with Fe(III)-π interaction, causing more oxygen vacancies (OVs) with more electrons in iron oxides. In the catalyst air-saturated suspension, the adsorbed pollutants complexed surface Fe(III) through their hydroxyl group donated electrons to around OVs, reducing the surface Fe(III) to Fe(II) and were destructed by Fe(III)-π interaction of the complexation. The addition of HO mainly acted as acceptor being reduced OH at the OV centers, causing higher degradation rate of pollutants due to both OH and the surface reaction. However, for the adsorbed hydrophobic pollutants onto the sites of peripheral structure in g-CN, HO was mainly decomposed into O by the synergistic effect of iron species and OVs. Therefore, the catalyst exhibited high Fenton-like efficiency for the degradation of hydroxyl-containing pollutants and hydrophobic pollutants mixing with the former. Our results demonstrate that the Fe(III)-π interaction could carry out the oxidation of pollutants on the catalyst surface, decreasing the consumption of HO, and the role of OVs depends on pollutant adsorption patterns.