Synthesis and characterization of carbon dots from coconut shell by optimizing the hydrothermal carbonization process

Abstract

Coconut shell is one of the major agro-by products vis-a-vis agro-waste generated by coconut processing units. At present, Coconut shells are largely utilized as feed material for thermal power conversion by various allied industrial sectors, which is a highly energy inefficient and ecologically unfriendly process. The present study aimed to generate activated carbon dots/ carbon nanomaterials with a wide range of potential applications through a relatively less energy dependant hydrothermal carbonization process. Hydrothermal carbonization is a one-step, simple, low cost and environmental friendly approach to obtain carbon dots. The findings demonstrate that coconut shells when subjected to hydrothermal carbonization process at 250^ᵒC for 6 h produced uniform-sized, stable, negatively charged and amorphous forms of carbon dots. Characterization of carbon dots using High-Resolution Transmission Electron Microscopy (HR-TEM), Scanning Electron Microscopy (SEM), Selected Area Electron Diffraction (SAED), X- ray Diffractometer (XRD), UV- Visible Spectroscopy, Particle Size Analyzer (PSA), Brunauer–Emmett-Teller (BET) Analyzer, Elemental Dispersive X-ray (EDX) analyzer and Fourier Transform Infrared Spectroscopy (FTIR) had conclusively confirmed the versatility of the carbon dots generation process and were able to achieve stable 2 nm-sized, spherical shaped carbon dots with numerous downstream applications. The study will help the conversion of agro-waste coconut shells into useful bio-based fluorescent carbon dots.