Highly selective amperometric sensors for carbon monoxide detection in exhaust gas

An amperometric electrochemical sensor based on LaGaO3 was demonstrated as highly sensitive to carbon monoxide (CO) in the temperatures ranging from 300 °C to 500 °C. In the present study, various Fe-doped LaGaO3 electrolytes (La0.8Sr0.2Ga0.8Mg0.2−xFexO3; x = 0.05, 0.10, 0.15, 0.2 and La0.8Sr0.2Ga1−xFexO3; x = 0.10, 0.15, 0.2, 0.3) coupled with Au10 wt%–In1.9Sn0.1O3 (ITO955) and RuO2–La0.6Sr0.4CoO3 (LSC64) as the electrode catalysts were investigated. Highest sensitivity was achieved at 8.83 mA/decade (at 500 °C) by doping 15 mol% Fe into electrolyte (denoted as LSGF 828515) among the examined electrolytes. The sensitivities of all studied sensors were high and the current increased with increasing CO concentration. The sensors were fast, highly sensitive to CO and almost insensitive to other coexisting gases such as CH4, CO2, and H2. Therefore, this sensor can be used for CO monitoring of exhaust gas from a small indoor combustion source.