Abstract
Three types of In2O3 nanoparticles decorated with Au, Pd and Pt nanoparticles, respectively, were synthesized by thermal decomposition method, and the effects of metal nanoparticles on their phase, microstructure, chemical state, carrier types were investigated with XRD, SEM/TEM, and XPS. Additionally, sensing properties to CO gas, such as sensitivity, etc., were examined with sensing apparatus. Au-decorated In2O3 nanoparticles exhibited the highest sensitivity to CO gas, with S = 5.59 at a 10 ppm CO gas concentration at 50 °C compared to Pd or Pt-decorated In2O3 nanoparticles. This can be interpreted as a much higher adsorption of oxygen molecules on the In2O3 surface due to the high oxygen vacancies in the In2O3 lattice, which generates an electron depletion region in the outer layer of In2O3 to sharply increase the resistance or the spill-over effect due to Au nanoparticles on In2O3. Au nanoparticles were observed in the TEM images and confirmed by XPS analysis.
Highlights
Environmental pollution has attracted growing attention due to its serious harm to human health
Catalyst-decorated In2O3 nanoparticles were synthesized by the thermal decomposition technique using reagents such as indium (III) nitrate hydrate InN3O3·6H2O, hexamethylenetetramine C6H2N4, sodium borohydride H4BNa, gold (III) chloride trihydrate HAuCl4·3H2O, chloroplatinic acid solution H2Cl6Pt, and palladium (II) chloride solution Cl2Pd, which were purchased from Sigma-Aldrich
In2O3-based gas sensors decorated with three noble metals (Au, Pd, and Pt) to detect carbon monoxide at temperatures near room temperature were fabricated and investigated using XRD, TEM, and XPS
Summary
Environmental pollution has attracted growing attention due to its serious harm to human health. Carbon monoxide (CO) is one of the most harmful gas contaminants and readily reacts with hemoglobin and damages the human body. CO is considered a major threat to environmental safety and human health, even at the very low concentration of 35 ppm. Greater exposure to carbon monoxide (CO) often causes death in everyday life. It is essential to develop high-sensitivity room temperature CO gas sensors capable of rapid responses and sensitive enough to detect parts per million concentrations when applied in domestic and industrial sectors. Available CO gas sensors have several issues, including low sensitivity, high working temperature, and slow response or recovery time [1,2,3,4,5]
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