Carbon monoxide sensor for PEM fuel cell systems

Power generation systems based on Proton-exchange membrane (PEM) fuel cells require sensors to detect carbon monoxide to extremely low levels (∼1 ppm) in the presence of hydrogen and other gaseous components (nitrogen, carbon dioxide, methane and steam). The CO sensors capable of working in reducing environments are almost non-existent. Development of a new CO sensor stable in H2-rich environment is described. The novel sensing approach is based on the adsorption of CO onto a film of an inorganic material that allows CO detection by monitoring resistance changes of the film in a simulated reformed gas, rich in H2. When suitable materials were used for the thick film approach, the resistance of the device exhibited a rapid and reversible sensitivity to carbon monoxide in the range 0–5000 ppm over a period of several days, in the presence of hydrogen and nitrogen.