Electrochemical performance of Pleurotus ostreatus-derived carbon prepared by different methods as electrode in supercapacitor

In this research, the impact of precursor preparation methods of biomass-derived carbon materials were investigated. Hydrothermal treatment with phosphoric acid solution, hydrothermal treatment with water, and direct pyrolysis were applied to prepare the carbon precursors from Pleurotus ostreatus stipe. Potassium hydroxide was applied for further precursor activation. The physicochemical characteristics of carbons were tested by X-ray diffraction, elemental analysis, nitrogen sorption, scanning electron microscopy, X-ray photoelectron spectroscopy and so on. Moreover, the electrochemical data of these carbon material based supercapacitors were collected by using an electrochemical workstation with Na2SO4 solution as electrolyte. Certain differences, such as surface morphology, specific surface area and elemental composition, were observed for carbon from different precursor preparation methods. The contents of C= O/carboxylic C (32.83%) and C–N/C–O–C (27.38%) of carbon obtained by directly pyrolysis and further potassium hydroxide activation (PCK) were higher than other carbon. PCK as electrode in supercapacitor had higher specific capacitance than Pleurotus ostreatus-derived carbon materials. Much vertical Nyquist plot and small diameters of the semicycle for PCK were observed. After the continuous charge/discharge test for 10000 cycles, the supercapacitor using PCK as electrode still keeps about 98% of its initial value.