Electrochemical decomposition of NO over composite electrodes on YSZ electrolyte

NO decomposition over electrochemical cells that involve a bilayered composite electrode has been investigated. NO was decomposed only after a minimum current density was applied and its conversion increased abruptly with increasing applied current. The compositions of phases and their spatial distribution on the cathode strongly influenced the decomposition activity as a function of the current density since they are directly correlated with the site and number densities of the triple-phase boundary and the electrochemically induced active site, i.e., F-center. The [(La2Sn2O7 + YSZ)/Pt] electrode could convert more than 85% of NO into N2 at 200 mA/cm2 whereas only 27% was decomposed over the platinum electrode although the latter was more electrochemically active at lower current ∼70 mA/cm2. The addition of Pt into the [(La2Sn2O7 + YSZ)/Pt] composite electrode not only expands the densities of the tpb and F-centers but also enhances competitive NO adsorption as indirectly confirmed by impedance spectroscopy, both of which promote NO conversion at the lower current density.