De-NOx reactor and NOx sensor using In3+-doped SnP2O7 with PtRhBa/C electrode

An electrochemical cell using an In3+-doped SnP2O7 proton conductor as the electrolyte exhibited comparable NO reduction and sensing properties at around 250 °C. NO was reduced to N2 most effectively when using a PtRhBa/C cathode by applying current to the cell. High electrocatalytic activity was maintained even in the presence of CO2 and H2O. PtRhBa/C was also found to be the most effective electrode material for NOx sensing. The sensor exhibited electromotive force (EMF) response towards the positive direction with increasing NO and NO2 concentrations. The polarization curves of NO/NO2 and water vapor indicated that the sensing mechanism is based on the mixed potential. The effects of added Rh and Ba to the Pt/C electrode were explained in terms of selective reduction and adsorption of NO/NO2 over the electrode surface, respectively.