Production of selective gas sensors based on nanoparticles of PdO/Fe3O4

Fabrication of gas sensors is witnessing great advancements due to recent progress in synthesis of metal-oxide nanoparticles with custom designed characteristics. Composition of nanoparticles allows access to the chemical features of the surface nanoparticles and utilization of physical features of the core nanoparticles. Furthermore, it enables formation of p − n heterojunctions among nanoparticles with depletion layers that enables to control the follow of charge carriers. Herein, nanoparticles of Fe3O4 and PdO are synthesized using a coprecipitation process and explored for their implementation for gas sensor applications. The mean grain sizes are 7.7 ∓ 2.3 nm and 6.4 ∓ 1.5 nm for Fe3O4 and PdO, respectively. The sensor devices are produced by depositing nanoparticles (dispersed) on substrates with pre-deposited interdigitated electrodes. Electrical characteristics are examined using impedance spectroscopy that enables calculation of the activation energy Ea = 0.66 ± 0.04 eV. The produced sensors are selective for both H2 and H2S within different concentration ranges, where their minimum responses at ambient temperature are 1200 and 10 ppm for H2 and H2S gases, respectively. The gas sensor devices fabricated in this work exhibit potential for practical implementation because of their numerous advantages that incorporate simplified fabrication technique, low power consumption due to their functionality at ambient temperature, extraordinary sensitivity, practical response time, as well as their core that consists of magnetic nanoparticles which simplify their recycling.