Abstract: A catalyst-coated membrane includes a proton-exchange membrane, an anode applied to a first side of the membrane, including at least one noble-metal-containing catalyst, an areal weight of the noble-metal-containing catalyst, based on the noble metal content, being less than or equal to 0.6 mg/cm2, and a cathode applied to a second side of the membrane, wherein an areal expansion of the catalyst-coated membrane is less than 20% after being held for two hours in water heated to 100° C.

Abstract: The present invention is directed to electrochemical gas sensors for the detection of combustible, flammable or toxic gases and to catalyst-coated membranes (CCMs) used therein. The gas sensor comprises at least one solid anion exchange membrane (AEM), a sensing electrode and a counter electrode. The sensing electrode comprises catalytically active material and anionic ionomer material, the weight ratio between the catalyst material and the anionic ionomer material in the sensing electrode is in the range of 3/1 to 99/1, preferably in the range of 4/1 to 30/1. Due to the use of anion exchange ionomer materials, the sensor can be made less expensive and suitable for high volume production. When applied for the detection of CO, the sensor shows good CO selectivity S(CO/H2) in the presence of hydrogen.