Electrosorption ability of CDI electrode is related with such textural characteristics as the pore structure, size and the ratio of mesopore to micropore. [3] In the recent study, the micropore with size less than 1nm showed an anomalous increase in carbon capacitance for the electric double layer capacitor. [4] Meanwhile, the well-connected pore channels are accessible for ion mobility in pore structure, formed by ample micropore and mesopore via intercalation. Therefore, it is utmost approach to develop micro/mesoporous carbon structures to enhance electrosorption capacity and construct facile ion transfer pathway.
In this work, we reported the development of meporous/microporous carbon composite for fast ion infiltration with high electrosorption capacity using different ratio of graphene nanoplatelet to activated carbon as CDI electrode. The electrode was characterized by SEM, XRD, BET and contact angle. To confirm electrochemical performance, cyclic voltammetry and electrochemical impedance spectroscopy was investigated. Also, the fabricated electrode was conducted Langmuir isotherm adsorption experiment to compare adsorption kinetics among the electrodes and CDI performance test. We found that the composite electrode had the improved process efficiency, attributed to the high conductivity and adsorption kinetics of graphene nanoplatelet compared with the electrode exploiting only activated carbon.
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[3] P.M. Biesheuvel, Dynamic adsorption/desorption process model for capacitive deionization, Journal of Physical Chemistry C, 2009, 113, 5636
[4] J. Chmiola, Anomalous increase in carbon capacitance at pore sizes less than 1 nanometer, Science, 2006, 313, 1760