| Electrochemical cells were constructed which reduced nitric oxide in oxygen-rich gas streams. The NO decomposition rates were studied on five different electrode materials: platinum, platinum doped with ceria, iridium, La;The measured decomposition rates of nitric oxide in the presence of high oxygen concentrations vary for the different electrodes. Low yield factors (measures of selectivity toward NO reduction) on the platinum-based electrodes are relatively insensitive to oxygen concentration, temperature, ceria doping, and electrode potential. The yield factor for the iridium electrode decreases as the temperature rises and as the applied current decreases. No nitric oxide decomposition was measured on the perovskite-type electrodes in the presence of oxygen.;Iridium was determined to be the best material for the reduction of nitric oxide in the presence of oxygen because it shows both low polarization losses and high yield factors. However, it is difficult to construct iridium electrodes which adhere to yttria-stabilized zirconia electrolytes.;The addition of carbon dioxide to the gas streams does not affect the nitric oxide decomposition rates on iridium. Water is not electrochemically reduced at the investigated voltages but does inhibit NO and O... |
