Green synthesis of multifunctional Cu/MnO@Biochar 3D structure as a high-performance anode material in Li-ion batteries and oxidative removal of Cango-red dye

The thermochemical conversion of biomass into biochar (BC) provides a valuable platform towards green and sustainable synthesis of functional carbon nanomaterials for advanced technological applications. Herein, we report biosynthesis of Oryza sativa (rice husk) biochar nanocomposites incorporated with bimetallic Cu and MnO (Cu/MnO) nanoparticles as multifunctional materials (Cu/MnO@BC) towards high-performance anode in Li-ion batteries (LIBs) and oxidative removal of organic dyes from aqueous solutions. The 3D network of Cu/MnO@BC nanocomposite as an anode in LIBs shows excellent initial specific discharge capacity of 1126 mhA g−1 at a current density of 0.1 Ag−1 with negligible fade in specific capacity during charge-discharge cycles due to high surface area and mesoporous structure of the nanocomposite. Further the Cu/MnO@BC nanocomposite anode displays superior reversible rate capacity that exceeds 1060 mhA g−1. The charge-discharge specific capacity and the coulombic efficiency shows excellent retention (almost 100 %) after 200 cycles of operation. The electrochemical impedance spectroscopy (EIS) at different cycles shows negligible decrease in Li+ diffusion coefficient thereby safeguarding the structural integrity of 3D Cu/MnO@BC after charge-discharge cycles. The textile industries widely utilize Congo-Red (CR) dye in their manufacturing processes which is a renowned pollutant that adversely affects the aquatic ecosystem. This mesoporous Cu/MnO@BC biochar nanocomposite provides a novel platform towards oxidative removal of CR dye from aqueous solution. The catalytic activity of Cu/MnO@BC was explored for the efficient removal of Congo red, a prominent dye widely used in textile industries, known for its persistence and environmental impact. Coupling of the Cu/MnO@BC and H2O2 enhances the CR removal possibly owing to the hydroxyl radical (●OH) formation. 70 % of CR is removed by Cu/MnO@BC without coupling while its CR whereas the removal efficiency enhances to 90 % when coupled with H2O2. Due to ease of bio derived synthesis, excellent electrochemical properties towards energy storage, and oxidative removal of CR dye, this Cu/MnO@BC nanocomposite could be used as multifunctional material as an anode in LIBs and oxidative removal of organic dyes.