Iron(III) oxide graphite composite electrodes: Application to the electroanalytical detection of hydrazine and hydrogen peroxide

Composite electrodes based on iron(III) oxide, Fe2O3, carbon powder and epoxy resin have been prepared and characterized using electrochemical methods and X-ray photoelectron spectroscopy (XPS). Initially composite electrodes were made by mixing micron sized carbon powder surface with iron(III) oxide. However, the voltammetric responses were unsatisfactory. Therefore, a new type of composite electrodes was made using carbon powder modified with iron(III) oxide via a wet impregnation procedure. This technique involves saturation of the carbon powder with iron(III) nitrate followed by thermal treatment at ca. 623 K forming iron(III) oxide on the surface of the carbon powder. Several key parameters such as percentage of carbon powder and iron(III) oxide as well as electrode geometry (electrode length) have been optimized. Composite electrodes show attractive performances for the electrochemical detection of hydrogen peroxide and hydrazine with detection limits of 0.12 mu M and 1.18 mu M respectively. These limits of detection are comparable to the detection limits attained by alternative analytical techniques and are lower than that obtained by other electroanalytical methods.