A catalytic filter based on Pt-CeO2 for selective methane detection with SnO2 sensors

A microfilter structure is proposed to modulate the transient process and reaction characteristics of gas diffusion to improve the selectivity. The sensor structure is divided into a sensitive part with sensing films and microfilter, which is composed of a porous ceramic carrier and catalytic film. This structure can avoid the problems of element diffusion and low adhesion caused by the poor contact between the sensitive film and the filter film. The catalytic combustion of interfering gases is verified. Results indicate that the sensitive and selective response of the microfilter sensor to CH4 are obviously improved. The microfilter could catalyze CO and ethanol into CO2 and H2O, and activate CH4 during the diffusion process, thus improving the activity of CH4. At the same time, sensors with a new structure exhibit stability, and high adaptability to the environment. Finally, with the help of the power-law response and in-situ catalytic characterization, the sensing mechanism is explained that sensors conform to the power-law response. That is the adsorption and reaction of oxygen on the surface are the basic mechanisms of the CH4 sensing response.