Functional biochar derived from Desmostachya bipinnata for the application in energy storage/conversion devices

Biochar amalgamated from grass Desmostachya bipinnata was used for supercapacitors and microbial fuel cell applications. Herein, the nitrogen driven simple carbonization method at 800 C was used without activating agent for preparation of biochar material. The crystalline state, morphology, structural porosity, thermal properties, and vibrational surface area of the biochar were examined using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), Raman, Brunauer–Emmett–Teller (BET), thermogravimetric analysis/derivative thermogravimetry (TGA/DTG), and X-ray photoelectron spectroscopy (XPS), and the surface functional groups containing oxygen are assessed. The electrodes in supercapacitor and microbial fuel cells are developed from the functionalized biochar material. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies with 1 M H2 SO4 electrolytes and 1-ethyl-3-methylimidazoliu thiocyanate (EMImSCN) ionic liquid were conducted to compare the electrochemical properties of the fabricated supercapacitor. The primed electrodes unveiled augmented capacitance in1M H2 SO4 electrolyte as ~ 26 F/g in comparison to EMImSCN ionic liquid as ~ 22 F/g. The microbial fuel cell (MFC) emboding the primed electrode as cathode material exhibited a maximum open circuit voltage (OCV) about 819 ± 25 mV and a power density maximum of 0.78 ± 0.09 mW/m3. Significant removal of 77.14% was achieved in chemical oxygen demand (COD) of the effluent with an average effluent concentration of 1423 ± 25 mg/l. On the basis of the obtained results, we can predict that Desmostachya bipinnata can be a very suitable precursor for preparing carbon material for its use as electrode material for electrochemical energy system (energy conversion and energy storage) devices.