Fabrication of Sm-doped porous In2O3 nanotubes and their excellent formaldehyde-sensing properties

Pure and Sm-doped In 2 O 3 porous nanotubes have been successfully fabricated by the single-capillary electrospinning method followed by calcination. The as-synthesized porous nanotubes were investigated by X-ray powder diffraction (XRD), energy-dispersive X-ray (EDX), scanning electron microscope (SEM), Raman spectra and X-ray photoelectron spectroscopy (XPS). It can be seen in SEM images that the surface of nanotubes is distributed with numerous pores. Gas sensing investigation reveals that Sm-doped In 2 O 3 porous nanotubes possess high-performance formaldehyde sensing properties. The response of gas sensors based on Sm-doped In 2 O 3 porous nanotubes was 54.37 towards 100 ppm formaldehyde at 240 °C, which was 5 times larger than that of pure In 2 O 3 porous nanotubes (10.87). The response and recovery times to 100 ppm formaldehyde were 9 and 40 s, respectively. Moreover, even at low concentration of 100 ppb formaldehyde, a detectable response of 2.1 can be observed. Furthermore, Sm-doped In 2 O 3 porous nanotube gas sensors have excellent selectivity to formaldehyde.