IrO2/SnO2 electrodes: prepared by sol-gel process and their electrocatalytic for pyrocatechol

IrO2/SnO2 (10%:90%, molar ratio) electrodes (ITEs) were prepared by the sol-gel method as an alternative to the electrode-position and thermal decomposition process. The electrodes were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS). From the results of XRD, oxide films prepared at low temperature were in amorphous state, while hydrous IrO2 crystal and cassiterite phase SnO2 were formed at 300 degreesC or even to 500 degreesC. The highly porous structure was confirmed by AFM. The electrochemical experiments demonstrated that the sol-gel method made the ITEs having a fast electron transfer process with good stability and the optimal preparation temperature was 400 degreesC for the highest electroactivity. Furthermore, the electrocatalysis of pyrocatechol on the electrodes was investigated. A quasi-reversible process occurred and a linear range over three orders magnitude (1 x 10(-2) - 10 mM) was obtained by differential pulse voltammetry (DPV). Meanwhile the detection limit of pyrocatechol was 5 x 10(-3) mM. This study indicated that the sol-gel method was an appropriate route to prepare the IrO2/SnO2 electrodes for the electrocatalytic of pyrocatechol.