Realization of an H₂/CO dual-gas sensor using CoPd magnetic structures

We demonstrated the application of CoPd magnetic devices in single (H₂) and dual (H₂ and CO) gas detection by varying the thin-film structure. The anomalous Hall effect provided the read-out signal of the devices. The dual-gas sensor was particularly useful for examining whether methane reformation by steam was completed during H₂ production where CO is a byproduct. Through in situ Fourier transform infrared and X-ray absorption spectroscopy, we discovered that H₂ detection involved a charge-transfer effect between Co and Pd in addition to a surface-adsorption process, for both multilayer and alloy structures; however, CO detection was solely associated with a surface-adsorption process, which only occurred in the alloy structure. The proposed devices demonstrated performances exceeding those of current commercial models (solid-state based) regarding power consumption (<5 mW) because they were not required to undergo a heating process. An Arduino prototype platform was employed to test the modularization of the device, and adequate feasibility was demonstrated.