Towards Low Temperature Operation of Catalytic Gas Sensors: Mesoporous Co 3 O 4 -Supported Au-Pd Nanoparticles as Functional Material.

It is shown that the operating temperature of pellistors for the detection of methane can be reduced to 300 °C by using Au-Pd nanoparticles on mesoporous cobalt oxide (Au-Pd@meso-Co 3 O 4 ). The aim is to reduce possible catalyst poisoning that occurs during the high-temperature operation of conventional Pd-based pellistors, which are usually operated at 450 °C or higher. The individual role of Au-Pd as well as Co 3 O 4 in terms of their catalytic activity has been investigated. Above 300 °C, Au-Pd bimetallic particles are mainly responsible for the catalytic combustion of methane. However, below 300 °C, only the Co 3 O 4 has a catalytic effect. In contrast to methane, the sensor response and the temperature increase of the sensor under propane exposure is much larger than for methane due to the larger heat of combustion of propane. Due to its lower activation energy requirement, propane exhibits a higher propensity for oxidation compared to methane. As a result, the detection of propane can be achieved at even lower temperatures due to its enhanced reactivity.