Air-fuel ratio sensor

Abstract

An air-fuel ratio sensor includes a solid electrolyte layer, a measuring electrode laminated on a first face of the solid electrolyte layer, a reference electrode laminated on a second face of the solid electrolyte layer which is different from the first face thereof, such that the reference electrode and the measuring electrode are opposed to each other with the solid electrolyte layer interposed therebetween, a porous diffusion resistance layer that permits gas to pass therethrough and covers the measuring electrode, and a catalyst layer including a catalyst metal and a base material on which the catalyst metal is supported. The catalyst layer permits gas to pass therethrough and covers the porous diffusion resistance layer. The catalyst metal is a platinum-palladium-rhodium alloy, and contains 2 to 9 mass % of rhodium when the overall amount of the catalyst layer is represented as 100 mass %.

Dependencies are inferred from the claim text.