Characterization of a zeolite-templated carbon by electrochemical quartz crystal microbalance and in situ Raman spectroscopy

Electrochemical quartz crystal microbalance was used to monitor the mass changes during the electrochemical characterization of a zeolite-templated carbon (ZTC) in 1 M H2SO4 medium. Under electrochemical oxidation conditions, a high anodic current and a net mass increase were recorded, resulting in the increase of the specific capacitance owing to the contribution of the pseudocapacitance, mainly derived from the hydroquinone–quinone redox couple. Under more severe electrochemical conditions, a net mass loss was observed, revealing that electrochemical gasification took place. Surface chemistry, before and after the electrochemical treatments, was analyzed through temperature programmed desorption experiments. Furthermore, in situ Raman spectroscopy was used to further characterize the structural changes produced in ZTC under the electrochemical conditions applied, supporting that high potential values produce the electrochemical oxidation and degradation of the carbon material.

Preparation of manganese oxide - graphite electrodes by electrophoretic deposition

Manganese oxide is a promising active material for supercapacitors (SCs) with pseudocapacitance due to its high capacitance and its environmentally friendly character. This paper deals with the preparation of electrodes for supercapacitors consisting of manganese oxide supported onto graphite by electrophoretic deposition. Manganese oxide powders were characterized and dispersed in water by controlling the colloidal and rheological behavior in order to obtain stable suspensions. Optimized manganese oxide suspensions were deposited onto graphite electrodes by electrophoretic deposition. The deposited mass per unit area in the electrodes was optimized by controlling the applied current density and the deposition time. It has been demonstrated that the introduction of a binder helped to improve the adherence to graphite; otherwise the deposit thickness obtained by EPD is limited and no films can be obtained by simply dipping. These conditions allowed us to obtain more homogeneous deposits with higher specific energy than without binder.