Sensitive H2 gas sensors based on SnO2 nanowires.

[Display omitted] • SnO2 colloidal nanowires was synthesized by solvothermal without high-temperature sintering. • Pd-SnO2 colloidal nanowires exhibited high response, fast response/recovery H2 sensing at 150 ℃. • Sensing mechanism was investigated by theoretical calculation and adsorption kinetics study. Sensitive H 2 gas sensors are highly desirable for the prediction and early-warning of H 2 leakage. Low-dimensional nanostructures of metal oxide semiconductor emerge as promising materials candidates, but it remains a challenge to preserve the nanostructures in the real sensors. In this work, we demonstrated highly sensitive H 2 gas sensors based on porous network of SnO 2 nanowires that exhibited ultrasmall diameter ∼ 2 nm. Colloidal SnO 2 nanowires synthesized via a solvothermal process were drop-coated onto the commercial alumina substrates, followed by in-situ annealing treatment at 350 °C to remove the surface ligands. The sensors exhibited sensitive response with linear dependence on the H 2 gas concentration ranging from 2 ppm to 100 ppm when operated at 250 °C. Typically, the sensor had a response of 13 toward 40 ppm of H 2 , with the response and recovery time being 15 s and 31 s, respectively. To further improve the sensor performance, Palladium doped SnO 2 nanowires were thoroughly investigated. It's shown that, the operating temperature of the sensor decreased from 250 °C to 150 °C after Pd doping, and the response and recovery time decreased to 6 s/3 s. The superb sensitivity was attributed to the enhanced gas reception, electron transport as well as utility factor owing to the network nanostructure of ultrathin SnO 2 nanowires and catalytic activity of Pd, according to theoretical calculation and adsorption kinetics studies. Combined with the excellent solution processability, the colloidal SnO 2 nanowires are potentially attractive for next-generation gas sensors with lower power consumption and integration with silicon-based substrates. [ABSTRACT FROM AUTHOR]