Porous Carbon Derived From Food Waste for Asymmetric Supercapacitor

Globally, by 2030, it is estimated that about 2 billion tons of food waste will be generated. This will not only cause economic losses but will also lead to serious environmental issues such as the emission of greenhouse gases (GHGs), bad odor, and land pollution due to the decomposition of food waste in an open environment and landfills. It is imperative to develop novel solutions to reduce food waste and perhaps valorize it into a valuable product, thereby reducing its environmental and economic impacts. Food waste can be considered a renewable and sustainable feedstock that can be used for chemical and biological processing for its valorization. In this investigation, hydrochar is derived from the hydrothermal carbonization (HTC) of food waste and subjected to chemical activation with potassium hydroxide (KOH), followed by thermal treatment at 800°C to produce porous carbon (POC). As-prepared POC is thoroughly characterized by Brunauer–Emmett–Teller (BET) surface area analyzer, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), and transmission electron microscopy (TEM). A specific capacitance of 112 F/g at 0.5 A/g current density is observed for POC in the three-cell standard electrochemical setup while asymmetric supercapacitor (ASC) fabricated with POC and Cu-ferrite electrodes exhibited energy and power densities of 29 Wh/kg and 1.36 kW/kg, respectively. Preliminary cost analysis shows a significantly lower cost for the POC derived from food waste than for a few other biomass feedstocks.