Doped Graphene and Curcumin@graphene Composites for Supercapacitance and Electrochemical Sensing Applications

Abstract

In this work, reduced graphene oxide (RG), sulphur-doped graphene (SG), and their respective composites with curcumin were synthesized and characterized for super capacitance and electrochemical H2O2 sensing applications. RG and SG were synthesized by a green one-pot hydrothermal method at a low temperature of 180º C. These samples were further used in oil bath heat treatment to synthesize the Curcumin@graphene composites. The morphological, and structural analysis of synthesized samples was done using Scanning Electron Microscopy, X-ray Diffraction, and Fourier Transform Infrared spectroscopy. Additionally, FTIR spectra offered valuable insights into the chemical functional groups and bonding characteristics of the materials. The SG electrode displayed a remarkable specific capacitance (Csp) of 139.32 F/g at a scan rate of 3 mV/s, outperforming both RG and GO electrodes. The notable enhancement in capacitance can be attributed to the introduction of sulfur doping, which created abundant open-edge sites and defects within the graphitic frameworks. These structural modifications led to increased spin densities and the creation of more active sites for charge storage. Therefore, it was confirmed that sulfur doping of graphene-based electrode materials is an effective approach to improve their electrochemical performances. Curcumin@graphene composites were found to have enhanced the electrochemical performance. The SG-Cur composite showed excellent enhanced capacitance of 214.18 F/g at 3 mV/s and also had a higher ECSA value = 2021 as compared with SG (215.62) The strong interlinking between sulphur and curcumin within the composite enables efficient charge migration, resulting in higher electrochemical performance. Excellent hydrogen peroxide sensing performance was shown by the RG sample with 0.0069 μM limit of detection (LOD) in a 2-12 mM range. This excellent performance can be attributed to the high ESCA (1045.5) of the RG sample. The highly porous structure, chemical stability, and high specific surface area of the curcumin@graphene composite electrode are believed to be the reasons behind their excellent supercapacitance. Reduced sensing performance of Curcumin@graphene samples for H2O2 detection can be attributed to interlinking between curcumin and graphene-based samples resulting in decrease ECSA.