One-step synthesis of palladium oxide-functionalized tin dioxide nanotubes: Characterization and high nitrogen dioxide gas sensing performance at room temperature.

Mesoporous palladium oxide (PdO)-functionalized tin dioxide (SnO) composite nanotubes (SPCTs) were prepared via one-step synthesis by electrospinning technology using ethanol and N,N-dimethylformamide (DMF) as solvents. Compared with pure SnO nanotubes, there were abundant mesopores and multiheterojunctions in PdO-functionalized SnO nanotubes. The sample with the molar ratio of SnO:PdO of 100:3 (3-SPCT) exhibited excellent response (∼20.30) as a sensor with fast gas response speed (∼1.33 s) to 100 ppm nitrogen dioxide (NO) at room temperature (RT), and the detection limit reached to 10 ppb. The improved gas sensing performance of the 3-SPCT sensor was mainly attributed to the synergistic effect: the unique SnO tubular structure and well-dispersed mesopores provided the gas diffusion and adsorption channels, oxygen defects and chemisorbed oxygen were taken as the electron trap and charge transfer active sites, and a large number of heterojunctions acted as electron transport channels, thereby increasing the transfer rate.