Measurement of potentials of cerium, praseodymium, terbium oxides on carbon pasted electrode

Potentials of oxides of praseodymium, terbium and cerium with respect to the saturated calomel reference electrode have been measured in H2SO4 solutions of various concentration at the constant temperature (25 deg C). The composition of the initial species was Pr4O7 (44.11% PrO2), Tb4O7 (36.10% TbO2) and CeO2 (pure). The potential of carbon paste electrode containing cerium dioxide has been shown to depend on activity of Ce(4) ions resulting from the oxide dissolution. The carbon paste electrode potential in the presence of praseodymium and terbium oxides is due to the oxygen emanated upon PrO2 and TbO2 reduction by water