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Description
Hydrogen (H₂) is a promising clean fuel, but its flammability in the 4–75% range necessitates rapid leak detection. Chemiresistive gas sensors offer an efficient solution due to their low cost, small size, and tunable properties. This study focuses on optimizing functional materials for H₂ sensing. (Ti,Sn)O₂ solid solutions were chosen for their superior sensing performance over pure oxides, and Pd was added to enhance catalytic activity and mitigate humidity effects. SnO₂, TiO₂, and (Ti,Sn)O₂ with a Ti:Sn ratio of 25:75 (TS25) were synthesized using standard procedures, with Pd-loaded samples (TSP) prepared by adding 1.5 at% Pd. FE-SEM and XRD analyses revealed nanoparticle morphologies (~10 nm) and single-phase structures: cassiterite SnO₂, anatase TiO₂, and rutile solid solutions. Screen-printed sensing layers were fired at 600 °C and electrically tested, confirming n-type behavior. At their optimal temperatures, the response to 100 ppm H₂ followed this order: TSP (400 °C), TS25 (450 °C), SnO₂ (450 °C), and TiO₂ (550 °C). Both TSP and TS25 detected H₂ from 0–1000 ppm, even at 60% humidity. Selectivity tests revealed CO as the main interferent, though H₂ still induced the strongest response.
Research supported by the Emilia-Romagna PR-FESR 2021-2027 Project “SENSIDROGEN” (www.sensidrogen.it).
