Amperometric sensor for selective and stable hydrogen measurement

Amperometric gas sensors in a three-electrode configuration were investigated for hydrogen measurements in atmospheres containing carbon monoxide. The hydrogen-sensing working electrode was based on a platinum black electrode deposited on a porous Teflon® substrate. To achieve selectivity, an FEP membrane was mounted at the gas inlet of the sensor. Hydrogen readily diffused through the FEP membrane and was detected on the Pt working electrode. The cross-sensitivity to gases such as carbon monoxide, ammonia and hydrogen sulfide was eliminated with nearly 100% efficiency in the short term. In addition, the poisoning effect of the carbon monoxide was virtually eliminated. Sensor stability to high levels of hydrogen was improved by the development of a hydrogen-insensitive reference electrode.