Abstract:
Biowaste conversion into activated carbon is a sustainable and inexpensive approach
that relieves the pressure on its disposal. Here, we prepared micro-mesoporous activated carbons
(ACs) from cucumber peels through carbonization at 600 ◦C followed by thermal activation at
different temperatures. The ACs were tested as supercapacitors for the first time. The carbon
activated at 800 ◦C (ACP-800) showed a high specific capacitance value of 300 F/g at a scan rate of
5 mV/s in the cyclic voltammetry and 331 F/g at the current density of 0.1 A/g in the galvanostatic
charge–discharge analysis. At the current density of 1 A/g, the specific discharge capacitance
was 286 F/g and retained 100% capacity after 2000 cycles. Their properties were analyzed by
scanning electron microscopy, energy-dispersive X-ray analysis, porosity, thermal analysis, and
Fourier-transform infrared spectroscopy. The specific surface area of this sample was calculated to
be 2333 m2 g
−1 using the Brunauer–Emmett–Teller method. The excellent performance of ACP-800
is mainly attributed to its hierarchical porosity, as the mesopores provide connectivity between the
micropores and improve the capacitive performance. These electrochemical properties enable this
carbon material prepared from cucumber peels to be a potential source for supercapacitor materials.
