Considering a large amount of expired foods such as expired bread are generated in the world every day

expired sliced bread activated carbon (EBAC) was prepared from expired sliced bread by carbonization

activation with 1 mol·L-1 KOH

neutralized with dilute hydrochloric acid

and then washed with deionized water and ethanol. The surface morphology

phase structure

surface functional groups

specific surface area and pore size distribution of expired sliced bread activated carbon were characterized by scanning electron microscopy (SEM)

X-ray diffraction (XRD)

Fourier transform infrared spectroscopy (FTIR)

nitrogen adsorption and desorption (BET). The electrochemical properties of activated carbon electrode materials were tested in a three-electrode system with the 3 mol·L-1 KOH electrolyte. The charge-discharge curves show that the specific capacitance of the electrode material reaches 352 F·g-1 at 0.5 A·g-1 current density. After 1000 cycles at 5 A·g-1 current density

the specific capacitance remains 99.87%

which shows good cyclic stability. At last

the Nyquist and Bode diagrams obtained by AC impedance measurement also shows that the expired sliced bread activated carbon has good supercapacitor performance.