Enhanced gas sensing performance of electrospun Pt-functionalized NiO nanotubes with chemical and electronic sensitization.

Pt-functionalized NiO composite nanotubes were synthesized by a simple electrospinning method, and their morphology, chemistry, and crystal structure have been characterized at the nanoscale. It was found that the Pt nanoparticles were dispersed uniformly in the NiO nanotubes, and the Pt-functionalized NiO composite nanotubes showed some dendritic structure in the body of nanotubes just like thorns growing in the nanotubes. Compared with the pristine NiO nanotube based gas sensor and other NiO-based gas sensors reported previously, the Pt-functionalized NiO composite nanotube based gas sensor showed substantially enhanced electrical responses to target gas (methane, hydrogen, acetone, and ethanol), especially ethanol. The NiO-Pt 0.7% composite nanotube based gas sensor displayed a response value of 20.85 at 100 ppm at ethanol and 200 °C, whereas the pristine NiO nanotube based gas sensor only showed a response of 2.06 under the same conditions. Moreover, the Pt-functionalized NiO composite nanotube based gas sensor demonstrated outstanding gas selectivity for ethanol against methane, hydrogen, and acetone. The reason for which the Pt-functionalized NiO composite nanotube based gas sensor obviously enhanced the gas sensing performance is attributed to the role of Pt on the chemical sensitization (catalytic oxidation) of target gases and the electronic sensitization (Fermi-level shifting) of NiO.