Electrochemical reduction of oxygen and nitric oxide at low temperature on Ce1−xPrxO2−δ cathodes

The ability of praseodymium doped cerium oxide materials to electrochemically reduce NO and O2 was studied using cone-shaped electrodes in conjunction with cyclic voltammetry, in the temperature range 200–400 °C. Four samples were studied; Ce1−xPrxO2−δ (x = 0.1, 0.2, 0.3 and 0.4). It was shown that the current densities in both NO an O2 gases increased with increasing praseodymium doping. Ce1−xPrxO2−δ had higher activity in an atmosphere containing NO than in an atmosphere containing O2 in most cases and this trend was stronger at the lower temperatures. Ce0.8Pr0.2O2−δ and Ce0.9Pr0.1O2−δ seemed to have the highest ratio of maximum cathodic current density (iNO/iO2iNO/iO2), which is used as an indication of a higher activity toward reduction of NO compared to reduction of O2. The apparent selectivity generally decreased with increasing temperature for all the compositions.