Incorporating Fe, Co co-doped graphene with PDI supermolecular for promoted photocatalytic activity: A story of electron transfer

Iron-cobalt dual single-atom anchoring on nitrogen-doped graphene (FexCoy-NG) improves the efficiency of migration and separation of photo-generated carriers. In this work, the perylene diimide (PDI) is self-assembled on the FexCoy-NG to form the FexCoy-NG/PDI composites by π-π interaction, which is reported for the first time. The bisphenol A (BPA) degradation of optimized 20% Fe0.2Co0.8-NG/PDI are nearly 100%, and the degradation rate is 1.5 and 12.7 times that of the self-assembled PDI and commercial-grade PDI. The high degradation performance by FexCoy-NG/PDI are mainly due to: (i) regulating the proportion of Fe-Co dual active sites content, so that it can achieve the synergistic interaction to facilitate the transfer of electrons in the catalytic reaction. (ii) PDI is uniformly dispersed by adding the FexCoy-NG, which increases the specific surface area of composites to adsorb more pollutants. Free radical trapping experiments and electron spin-resonance spectroscopy characterization confirmed that the O2-, OH, 1O2 and h+ are the main reactive species (RSs) for BPA degradation. Under the attack of RSs, BPA completes the processes of hydroxylation, demethylation, aromatization, ring-opening, and finally complete mineralization into CO2 and H2O. These results revealed that Fe0.2Co0.8-NG/PDI photocatalysts may be efficiently applied for the remediation of phenol contaminated natural waters.