Shorea robusta derived activated carbon decorated with manganese dioxide hybrid composite for improved capacitive behaviors

Shorea robusta derived activated carbon decorated with MnO2 was successfully prepared. Thus prepared activated carbon was characterized by Thermogravimetric Analysis (TGA)/Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Raman spectra, Fourier Transform Infrared Spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), and X-ray Photoelectron Spectroscopy (XPS). Results revealed that prepared material was found to be amorphous having oxygenated surface functional groups with the specific surface area 1270 m2 g−1 (±0.57%). Electrochemical characterization was also performed by three-electrode system where carbon electrode was used as working electrode, platinum plate was used as counter electrode and Ag/AgCl electrode was used as a reference electrode. The experiments were performed in 6 M aqueous KOH using Cyclic Voltammetry (CV), Galvanostatic Charge–Discharge (GCD) and Impendance Spectroscopy (EIS). The specific capacitance acquired from GCD at 1 Ag−1 was found to be 136.3 Fg−1 (±0.15%) with 0.44 Ω (±0.02%) ESR. The 97% capacitance retention was observed after 1000 cycles. The energy density of carbon electrode was found to be 3.0 (±0.25%) W h kg−1 at 100.5 (±0.20%) W kg−1 power density. The working carbon electrode was replaced by “hybrid composite electrode” which showed the ideal capacitive behaviors having 480.4 (±0.20%) F g−1 capacitance, 24 (±0.26%) W h kg−1 specific energy density and low ESR value of 0.41 (±0.02%) Ω. The results showed that the desirable electrochemical capacitive performances enable the hybrid composite to act as a new bio material for high-performance supercapacitors and energy storage devices.