Green synthesis of highly fluorescent carbon quantum dots from Citrus limetta juice

Abstract Green synthesis of Carbon Quantum Dots (CQDs) has gained a lot of interest due to their wide applications in various fields such as biomedical and optoelectronic devices. In the present study, highly fluorescent CQDs are synthesized using a natural precursor sweet lemon through a simple one-pot hydrothermal method. The resulting CQDs exhibited green fluorescence under a UV source and a high quantum yield of 9.28% at the excitation wavelength 370 nm. The synthesized CQDs showed good solubility and stability because of the oxygenated groups present on the surface confirmed by X-ray photoelectron Spectroscopy and zeta potential. The X-ray diffraction, Scanning Electron Microscopy and Dynamic light scattering indicated that the CQDs are spherical in shape, possess amorphous or poor crystalline nature and the particle size varies between 5–22 nm with an average diameter of 10 nm.