Synthesis of N-Doped Carbon Quantum Dots by Hydrothermal Synthesis Method and Investigation of Optical Properties

Abstract

Carbon quantum dots (CQDs); It is a carbon-based nanomaterial that has become popular in recent years due to its advantages such as biocompatibility, tunable fluorescent properties, simple and economical synthesis methods. In this study, synthesis of N-doped carbon quantum dots by hydrothermal synthesis method using tangerine juice, onion shell and ethylenediamine was investigated. The structures and optical properties of the synthesized carbon quantum dots were illuminated by photoluminescence (PL), X-ray Diffractometer (XRD), Infrared (IR) and UV-vis spectrometer. Electrochemical properties were examined by the cyclic voltammetry (CV) technique. The stability of N-doped carbon quantum dots (at 1st, 10th, 15th and 26th days) and pH-dependent emission properties were investigated. Peaks are seen at 285 nm and 347 nm in the UV-vis spectrum proved the presence of C=O and C=N bonds. It has been observed that there is a redshift in the absorption peak due to the amine groups in the structure of the N-doped carbon quantum dots. As a result of the XRD analysis, it was seen that the N-doped carbon quantum dots were in an amorphous structure. The FTIR spectrum of N-doped carbon quantum dots characteristic absorption bands of shows N-H vibration stretching and C-H bending peaks at 3240 and 2923 cm-1, respectively. These functional groups seen in the structure showed that N-CQD is bonded by hydrogen bond. In 1574 cm-1 and 1336 cm-1 C=O vibration stretching peaks and C-N vibration stretching peaks are observed. In the next step, the electrochemical properties of the carbon dots were examined by cyclic voltammetry technique. Different scanning rates (10-1000 mV/s) were used to understand and clarify the substance (mass) transport to the electrode surface.