摘要：

In this paper, ultra-sensitive hydrogen (H2) gas sensors based on flame-spray-made Pd-catalyzed SnO2 nanoparticles is presented. Pd-loaded SnO2 crystalline nanoparticles with high specific surface area and well-controlled size were synthesized by flame spray pyrolysis (FSP) in one step. The particle properties were characterized by XRD, BET, SEM, \{TEM\} and \{EDS\} analyses. The H2-sensing performances in terms of sensor response, response time and selectivity were optimized by varying Pd concentration between 0.2 and 2 wt%. An optimal Pd concentration for \{H2\} sensing was found to be 0.2 wt%. The optimal sensing film (0.2 wt% Pd/SnO2, 10 μm in thickness) showed an ultra-high sensor response of ∼104 to 1 vol% of \{H2\} at 200 °C and very short response time within a few seconds. Moreover, the optimum sensing temperature of Pd-loaded SnO2 films was shifted to a lower value compared with that of unloaded SnO2 film. The significant enhancement of \{H2\} sensing performances was attributed to highly effective spillover mechanism of well-dispersed Pd catalyst in SnO2 matrix at low Pd-loading concentration. Furthermore, the catalyst selectivity of Pd toward \{H2\} was found to be significantly higher than those of two other noble metals including Pt and Ru, respectively. Therefore, the flame-made 0.2 wt% Pd/SnO2 sensors is one of the most promising candidates for highly sensitive and selective detection of H2.

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