Hydrothermal Synthesis of CuO-SnO2 and CuO-SnO2-Fe2O3 Mixed Oxides and their Electrochemical Characterization in Neutral Electrolyte

Hydrothermal synthesis of CuO-SnO2 and CuO-SnO2-Fe2O3 mixed oxides is done in an autoclave using the precursors and urea. The powders are characterized by XRD, XRF, SEM and XPS. Their electrochemical behavior is studied using cyclic voltammgorams in 0.1 M KCl solution. Introduction of Fe2O3 to CuO-SnO2 increased the capacitances by twofold which decreased on continuous cycling, approaching a limiting value. The changes in electrochemical capacitances are explained based on the hypothetical band alignment of p-type CuO, Fe2O3 and n-type SnO2. The decrease in electrochemical capacitances on cycling has been attributed to the passive film formation on the surface of the mixed oxide electrode surfaces.