Thin film of copper hexacyanoferrate dispersed on the surface of a conducting carbon ceramic material, SiO2/ZrO2/C-graphite: characteristics and electrochemical studies

SiO2/ZrO2/C-graphite materials (SZC) were prepared by the sol-gel method presenting two compositions and designated as: (a) SZC30 (SiO2= 50%, ZrO2= 20%, C= 30%) and (b) SZC20 (SiO2 =60%, ZrO2= 20%, C= 20%) in wt.%. The material structure was investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The electrical conductivities obtained for the pressed disks of these materials were 4 and 18 S cm-1 for SZC20 and SZC30, and the specific surface areas (determined by the BET method) of the carbon ceramic composites were 45 and 12 m² g-1, respectively. A copper hexacyanoferrate thin film was grown in situ on the material surface containing 30 wt.% C (SZC30). The thickness of the film was estimated as 110 nm. The midpoint potential for the redox process was dependent on the KCl supporting electrolyte concentrations in the range between 0.1 and 1.0 mol L-1 and the charge transfer resistance determined by electrochemical impedance spectroscopy experiment was 23.8 ohm cm².