Green Synthesis of Zinc Oxide Nanoparticles Using Black Tea Extract and its Potential as Anode Material in Sodium-Ion Batteries

Metal oxides have been exploited with various desired architecture due to their wide applications. One of the promising advantages of metal oxides such as zinc oxide (ZnO) is it can exhibit in many forms of nanostructures. Green synthesis approach is preferable as it is environmentally friendly and offers easy fabrication. In this study, black tea extract has been used to synthesize zinc oxide nanoparticles (ZnONPs) and further calcined at 500, 700, and 900oC. The physical properties of the ZnONPs were characterized using thermogravimetric analysis, Fourier transform infrared, scanning electron microscope, X-Ray diffraction, and Brunauer–Emmett–Teller specific surface area. The ability of the ZnONPs as anode material for sodium-ion batteries was investigated via cyclic voltammetry and galvanostatic charge-discharge. A pure phase of the ZnONPs was obtained with nanosized particles ranging from 90 to 200 nm in diameter. The ZnONPs showed a high initial discharge capacity of ~200 mAh g-1 and a promising discharge capacity retention of ~60% after 100 cycles. Therefore, the ZnONP nanoparticles obtained through the green synthesis using black tea extract have a potential application as an anode in a sodium-ion battery.