Carbon pre-protected iron strategy to construct Fe, C-codoped g-C3N4 for effective photodegradation of organic pollutants via hole oxidation mechanism

Improving photocatalytic activity in graphitic carbon nitride (g-C3N4) by enhancing charge transfer and light absorption remains a challenge. Herein, iron-loaded carbon (FeC) was first prepared at low temperature, and then the Fe, C-codoped g-C3N4 (FeC–CN) was synthesized by high temperature thermal copolymerization of FeC with melamine. The carbon shell of FeC prevented the formation of iron oxide during high temperature thermal copolymerization, and Fe as electron channels existed in the interlayer, meanwhile, C atoms of FeC replaced part of the N atoms in the triazine ring. This designed structure facilitates in-plane and interlayer transfer of photogenerated carriers, as well as the separation of photogenerated carriers. Additionally, the UV–visible absorption spectra have demonstrated that the substitution of C atoms can greatly enhance visible light absorption. The catalyst exhibits significantly increased photocatalytic activity and excellent stability compared to g-C3N4. Interestingly, different from the reactive oxygen species-based g-C3N4 catalysis reaction, the degradation of organic pollutants was found to initiate from a hole-involved non-radical pathway. The increased electron transfer facilitates the reduction of O2 via a one-step two-electron pathway to generate hydrogen peroxide.