Synthesis of Biochar from Microwave Assisted Co-Pyrolysis of Tea Waste and Coal for Supercapacitor Application

Abstract

Rechargeable energy sources are becoming more important due to the current trend toward smaller portable electronic devices. The most promising option for extracting energy among the different non-conventional energy devices is the supercapacitor. In this work, biochar is produced from the co-pyrolysis of the tea waste, coal, and their blends (75:25, 50:50, and 25:75) utilizing the microwave-assisted pyrolysis at 450W, 2.45GHz. The obtained biochar was activated using the double crucible method, taking biochar and KOH in the ratio 1:1, to improve its surface area and porosity. The activated carbon was subsequently combined with TiO2 to enhance electrochemical conductivity and stability. A biochar-based activated carbon–titanium dioxide (AC–TiO2) composite is synthesized for use in supercapacitors. A two-electrode system device is fabricated containing biochar, conductive carbon, and Nafion in the ratio 8:1:1. Structural and morphological analysis validated the effective integration of TiO2 into the porous activated carbon matrix, yielding synergistic interactions between the activated carbon's high surface area and the pseudocapacitive properties of TiO2. Electrochemical investigations indicated that the AC–TiO2 composite had enhanced specific capacitance and cyclic stability, relative to pure activated carbon, indicating its potential as an effective electrode material for high-performance supercapacitors. This study emphasizes a sustainable method of employing biochar-derived activated carbon combined with metal oxide for enhanced energy storage systems.