Surface activated Co3O4/MoO3 nanostructured electrodes by air-plasma treatment toward enhanced supercapacitor

Herein, nanostructured Co3O4, MoO3, and Co3O4/MoO3 composite electrodes were prepared via hydrothermal synthesis and investigated for supercapacitive properties. The Co3O4/MoO3 composite electrode with equal weight ratio (named C5M5) showed the highest electrochemical properties compared to other electrodes. Air-plasma treatment further enhanced electrochemical performances owing to synergistic effects and surface activation of the Co3O4/MoO3 composite. The air-plasma surface-activated Co3O4/MoO3 composite (i.e. C5M5-P) electrodes exhibited a specific capacitance of 141F g−1 at 1 A g-1 in 1 M potassium hydroxide electrolyte. The fastest charge transfer and smallest resistance (1.64 Ω) were recorded for optimal electrode as demonstrated by Nyquist plots analysis. The surface-controlled process provided more than 50 % of capacity for the scan rates above 0.2 mV s−1, indicating the efficient pseudocapacitive behavior and showing the outstanding rate capability. The C5M5-P electrode exhibited superior cycling stability with 91.4 % capacitance retention at 3 A g-1 for 1,000 cycles.