*2.1. Materials*

Raw materials required to synthesis activated carbon are eucalyptus leaves, zinc chloride (ZnCl2), hydrochloric acid 35% (HCl), ethanol (>99% purity), distilled water (DI), and urea (CH4N2O) reagents were purchased from Merck India Pvt Ltd. (Singapore). Nickel foam has current collector with (0.5mm × 20cm × 30 cm) dimensions purchased from (Global nanotech Pvt. Ltd., Gujarat, India).
