Construction of g-C3N4/Fe-MOFs Type-Ⅱ heterojunction promotes photo-Fenton degradation of doxycycline

A type-II heterojunction photo-Fenton catalyst g-C3N4/Fe-MOFs was synthesized with the utilization of waste PET by dielectric barrier discharge (DBD) plasma. The coupling of Fe-MOFs enhanced the visible-light absorption regions of g-C3N4, and induced the formation of type-II heterojunction, which inhibited the recombination of photo-generated electrons and holes. g-C3N4/Fe-MOFs exhibited a much higher photo-Fenton catalytic performance, which was 4.42 and 3.30 times higher than that of g-C3N4 and Fe-MOFs for the degradation of doxycycline (DOX), respectively. The enhanced photo-Fenton catalytic performance could be attributed to the synergistic electron transfer interface between g-C3N4 and Fe-MOFs, thus inhibiting the recombination of photo-generated electrons and holes. The possible mechanism of photo-Fenton degradation of DOX with g-C3N4/Fe-MOFs was proposed based on the radical trapping experiments, as well as the characterization of EPR and Mott-Schottky. This research could provide an efficient and green method for the utilization of waste PET and the treatment of antibiotic wastewater.