In this work, glucose was firstly used as the precursor to produce porous carbon electrodes by hydrothermal carbonization (HTC) at 260℃, which is accomplished under mild and simple condition and is adaptable for wide feedstocks. Then, the porosity of the carbon electrodes has been improved by chemical activation with different amount of KOH at 800℃. The effects of different mass ratio of glucose to KOH (1:0, 1:1, 1:2, 1:3 and 1:1) on chemical activation efficiency have been studied. Scanning electron microscopy (SEM) images and Raman spectra of the porous carbon electrodes before and after activation are shown Fig. 1. Clearly, the glucose-derived porous carbon exhibits a sphere shape, and the pore structure has been greatly changed before and after KOH activation. It is notable that microspores of the porous carbon sphere were clearly enlarged after activation, and the enlarged mesopores are proper candidate as supercapacitor electrode.
Fig. 2 presents the current-voltage (C-V) curves of different glucose-derived porous carbon microelectrodes at different scan rate in 1M Na2SO4electrolyte. For all samples, the CV curves exhibits a symmetric rectangular shape, which indicates the behavior of electric double layer capacitors. The increased corresponding currents of glucose-derived porous carbon indicates the specific capacitance is increased after KOH activation. The specific capacitances of glucose-derived porous carbon with 1:3 (mass ratios of glucose to KOH) is reached 207 F/g. The The electric capacitance is strongly associated with the improved porous structure after KOH activation.
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