Highly selective amperometric sensors for carbon monoxide monitoring

Abstract

An amperometric carbon monoxide sensor using Fe-doped LaGaO₃ oxides as electrolyte was investigated. The electrodes which are Au10wt%-ITO955 (as cathode) and RuO₂-LSC64 (as anode) were coated on each side of the electrolyte and connected with Au mesh and Pt mesh, respectively. The fabricated sensor was placed inside a ceramic tube which was attached with a gas flow assembly and external electrical contacts. The operating temperature is in the range of 300℃ to 500℃. From this study, the perovskite compound doped with 15mol% Fe into Ga site (LSGF828515) showed the highest sensitivity and its sensitivity increased with increasing temperature. Moreover, the examined sensor exhibited higher selectivity to carbon monoxide compared with that of coexisting gases such as carbon dioxide, methane and hydrogen. Namely, the sensor has no significant responses to these coexisting gases, even hydrogen which is quite reactive to oxidation reaction. The effect of additive adding into anode (LSC64) was studied. It was found that LSC64 doped with Pt or Pd exhibited higher responses compared with that of non-doped LSC64 case. In addition, under sensing measurement conditions, there were no effects of gases or other factors on the sensor’s structure.