Green Synthesis of Value-Added Fluorescent Carbon Dots from Sugarcane Bagasse and Their Antioxidant, Reducing and Catalytic Activities

Development of value-added nanomaterials from agrowaste biomass is a promising strategy to overcome environmental issues caused by them as are mostly discarded or incinerated. Sugarcane bagasse (SCB) is a major residue of agro-industries and possesses the abundant resource of carbon. Herein, different types of highly photoluminescent carbon-dots sc-CDs (1-3) were synthesized from agrowaste biomass SCB by ecofriendly one-pot hydrothermal method. The as-synthesized sc-CDs showed green fluorescence around 457 nm with the excitation wavelength (lambda(ex)) in the range of 340-420 nm with absolute quantum yield of 12.31%. Fourier transform infrared spectroscopy exhibited characteristics absorption bands for C-H, O-H, and COOH. Scanning electron microscope showed sc-CDs morphologically spherical and mono-dispersed. Energydispersive X-ray spectra showed the presence of carbon (51.58%) and oxygen (34.15%) in sc-CDs. X-ray diffractions analysis demonstrated two intense peaks centered at 28.35 degrees and 40.55 degrees, which confirmed the crystallinity along with average size of 32 nm. Moreover, obtained sc-CDs exhibited significant scavenging activity using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay with EC50 values of 2.8, 2.7 and 3.9 mu g/ml for sc-CDs (1-3), respectively. The maximum total reducing capability was calculated to be 4.9 mg gallic acid equivalents (GAE/g) for sc-CDs-2 using Folin-Ciocalteu assay. Additionally, sc-CDs-2 enhanced the catalytic performances of sodium borohydride (NaBH4) for complete degradation of methylene-blue dye within 12 min and rate constant was also determined. In conclusion, sc-CDs (1-3) could be used as value-added nanomaterials, antioxidants and as probing agents in biomedical sciences as well as for removal of organic pollutants.