Single-route synthesis of binary metal oxide loaded coconut shell and watermelon rind biochar: Characterizations and cyclic voltammetry analysis

Abstract

Generally, the type of biomass precursors is one of the key factors affecting the properties of synthesized biochar. This novel study therefore examined the single-route preparation of coconut shell and watermelon rind biochar with the combination of two types of binary metal oxide, iron nickel oxide (Fe2NiO4), and cobalt iron oxide (CoFe2O4) by employing a novel vacuum condition in an electric muffle furnace. The samples were characterized by several methods such as Fourier transform infrared (FTIR), field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) Surface Area. The optimum pyrolysis temperature for producing a high surface area of 322.142 m2/g and 441.021 m2/g for coconut shell biochar and watermelon rind biochar, respectively, was recorded at 600 °C. FTIR analysis revealed lesser adsorption bands found in FTIR spectrum of the samples with higher pyrolysis temperature (500–700 °C). In addition, FESEM results also revealed the surface changes of the samples with the impregnation of CoFe2O44 and Fe2NiO4. Furthermore, the value added application of biochar in electrochemical energy storage has been explored in the present work. In typical three-electrode configuration, WR-BMO 600 exhibits about 152.09 Fg−1 with energy density about 19.01 Wh kg−1.