Hydrothermal Carbonization of Walnut Shell Biomass to Biochar for Supercapacitor Application

Hydrothermal carbonization is now emerging to address society's global sustainability problems by reprocessing several industrial and agricultural wastes to derive promising carbonaceous materials such as graphene, biochar, and activated carbon. This approach will further resolve the difficulties related to the safe recycling of waste materials and also the consumption of fossil fuels. This work focuses on synthesizing biochar via hydrothermal carbonization at temperatures 220 °C and residence time (6, 12, 18, and 24 h) and their effects on product yield and other parameters studied. Characterizations of biochar produced at different times were carried out using techniques like X-ray diffraction, UV-Visible Spectroscopy, and N2 adsorption/desorption isotherm. The biochar yield reduced from 56.4-40.2 wt-% with a rise in dwelling time. BET surface area was found to increase as we increased the reaction time. On the base of the maximum surface area, electrochemical analysis was performed to check the role of biochar as a supercapacitor electrode.