To examine the electrochemical performance of the as-prepared
Co0.85Se nanostructures for supercapacitors, the CV and GCD
measurements were employed in a three electrode configuration
within 3 M KOH aqueous electrolyte. Fig. 4a shows the CV curves ofthe as-prepared Co0.85Se electrode at various scan rates ranging
(10e50 mV s-1) in the potential of 0e0.6 V. It is noticeable that a
pair of redox peaks are observed in each CV curve, which correspond
to the typical faradic reaction among transformation of Co2þ/
Co3þ/Co4þ in alkaline solution [31].