Sensitive H2 gas sensors based on SnO2 nanowires

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 SnO2 nanowires that exhibited ultrasmall diameter similar to 2 nm. Colloidal SnO2 nanowires synthesized via a solvothermal process were drop-coated onto the commercial alumina substrates, followed by in-situ annealing treatment at 350 degrees 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 degrees 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 SnO2 nanowires were thoroughly investigated. It's shown that, the operating temperature of the sensor decreased from 250 degrees C to 150 degrees 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 SnO2 nanowires and catalytic activity of Pd, according to theoretical calculation and adsorption kinetics studies. Combined with the excellent solution processability, the colloidal SnO2 nanowires are potentially attractive for next-generation gas sensors with lower power consumption and integration with silicon-based substrates.

Automated summary

Highly sensitive H-2 gas sensors based on porous network of SnO2 nanowires were demonstrated in this study, with improved performance and shortened response/recovery time after Pd doping. The superb sensitivity of the sensor was credited to the ultrathin SnO2 nanowires network structure and the catalytic activity of Pd.