Hydroxyl-/Carboxyl-Rich Graphitic Carbon Nitride/Graphene Oxide Composites for Efficient Photodegradation of Reactive...

In this work, a protonated graphitic carbon nitride (P-g-C₃N₄)-coated graphene oxide (GO) composite (GO/P-g-C₃N₄) was prepared via wet-chemistry exfoliation, followed by a freeze-drying process. The GO/P-g-C₃N₄ composite was found to have an outstanding photodegradation performance effect on the reactive red 195 (RR195) dye and very strong antibacterial properties. Both the GO structure and the dispersed state of P-g-C₃N₄ were found to play a significant role in enhancing the photocatalytic activity of GO/P-g-C₃N₄. The GO/P-g-C₃N₄ obtained via freeze-drying retained a large number of oxygen-containing groups and showed higher catalytic activity and reusability than the reduced GO (rGO)/g-C₃N₄ obtained via thermal reduction. Characterization of the samples indicates that GO/P-g-C₃N₄ has a higher specific surface area and photocurrent density than rGO/g-C₃N₄; it is likely that these properties lead to the superior photocatalytic activity observed in GO/P-g-C₃N₄. Adsorption energy calculations indicate that O₂ can be readily adsorbed onto the GO surface, which results in stronger oxidizing superoxide anion radicals (^•O₂^-) and holes (h⁺); these active radicals can rapidly degrade RR195 dyes. Moreover, broad-spectrum antibacterial activity (demonstrated against Staphylococcus aureus and Escherichia coli) was observed in the case of the GO/P-g-C₃N₄ composite irradiated with visible light. This work offers new insights into the design of cost-effective g-C₃N₄-based photocatalysts for environmental remediation.