Synthesis and characterization of Co3O4 nanoneedle structures for enhancing the supercapacitive performance

The present study focuses on the synthesis of Co 3 O 4 nanoneedles utilizing a deep eutectic solvent (DES) comprising choline chloride and urea, renowned for its environmentally advantageous characteristics. The deposition time was modified to achieve the desired Co 3 O 4 nanoneedle structure, as indicated by several analyses including structural, vibrational, morphological, elemental, surface area, and pore distribution examinations. Following the initial characterization, other electrochemical storage characterizations were conducted. Experimentally it has been found that the optimum Co 3 O 4 samples yielded 1-D mesoporous nanoneedle structure with the features like (i) a substantial presence of oxygen vacancies, (ii) a relatively greater surface area, and (iii) a suitable pore size. As a result, of which it shows significant specific capacitance of 880 Fg - 1 when subjected to a current density of 0.66 Ag -1 in a 2 M KOH aqueous electrolyte. Additionally, it displayed excellent retention of 118% at 60 mVs - 1 scan rate after undergoing 5000 cycles. Moreover, a symmetric supercapacitor with a liquid electrolyte was constructed using identical nanoneedle Co 3 O 4 materials as both the cathode and anode. The experimental results demonstrated a specific capacitance of 98.39 Fg - 1 at a current density of 0.66 Ag -1 . Furthermore, the device exhibited an energy density of 18 Whkg - 1 along with a power density of 200 Wkg - 1 , demonstrating exceptional cycling stability of 94% over a span of 5,000 cycles.