Facile and Ultrafast Green Approach to Synthesize Biobased Luminescent Reduced Carbon Nanodot: An Efficient Photocatalyst

Rising awareness pertaining to global waste management and environmental issues challenges the development of an efficient metal-free photocatalytic system for visible light-assisted degradation of organic contaminants. We herein report the synthesis of biobased luminescent reduced carbon nanodots (RCDs) (3 nm average size) by green reduction of starch-based carbon nanodots (CDs) using aqueous extracts of Calocasia esculenta leaf, Mesua ferrea Linn leaf, tea leaf, and flower bud of Syzygium aromaticum. The reduction was found to be ultrafast (3 min) under sonication using Calocasia esculenta leaf extract in the presence of Fe3+ ions at room temperature. The synthesized RCD is an efficient photocatalyst for the degradation of model dirt like methylene blue, methyl orange, and their mixture as well as toxic chemicals like bisphenol A under normal sunlight. These degradations followed the pseudo-first-order kinetics model. The catalytic efficiency of RCD was significantly higher than that of CD. The structure of RCD was characterized by UV-visible, Fourier transform infrared, energy-dispersive X-ray, and Raman spectroscopic analyses as well as X-ray diffraction and transmission electron microscopic studies. The photoluminescence characteristic of RCD was analyzed by fluorescence spectroscopy. The results showed that exploration of sustainable resource-based RCD may offer a novel scope in resolving environmental and ecological problems.