Eco-Friendly Transition-Metal-Ion-Doped rGO Nanocomposites with Enhanced Photocatalytic Activities

Improving the photocatalytic properties of various types of metal oxides is becoming increasingly important in terms of environmental factors. Carbon allotropes are eco-friendly materials, and improving their photocatalytic properties via doping-induced modifications is one of the most attractive research areas. In this context, various first-row transition-metal-ion-doped reduced graphene oxide samples are synthesized and characterized using high-resolution transmission electron microscopy along with X-ray absorption spectroscopy to investigate their morphological and electronic structures at the molecular level. Transition metal-ion doping produces several defect structures at the oxygen functionalities of reduced graphene oxide nanocomposites (rGO). Such defect structures are well correlated with their photocatalytic activity; Cr@rGO and Fe@rGO exhibit decent activities among the four tested rGO samples in the photocatalytic degradation of organic pollutants and selective oxidation of 2,5-hydroxymethylfurfural. To test the environmental factors, cytotoxicity tests are performed by incubating the modified rGO with human skin cells; Fe@rGO is found to be the least toxic. Therefore, Fe@rGO displayed both enhanced photocatalytic activity and environment-friendly character as compared to the bare rGO, indicating that it is a plausible candidate for application in the petrochemical transformation of biomass without environmental concerns.