Fabrication, characterization and excellent formaldehyde gas sensing of Tb-doped In2O3 beaded-porous nanotubes

The pure and Tb-doped In2O3 beaded-porous nanotubes (BPNTs) are fabricated by simple electrospinning method. The crystal phase, morphology and chemical composition of the obtained samples were analyzed by characteristic techniques (XRD, FE-SEM, TEM, EDS, XPS, etc.). The mechanism of forming BPNTs structure was studied, and phase separation plays a key role in the process of formation. A series of sensing tests toward formaldehyde gas showed that 6mol% Tb-doped In2O3 BPNTs exhibited the best sensing performance: high response (75-50ppm), shorter response and recovery times (2s and 12s), low limit of detection (LOD, 1.27-100ppb), good selectivity and long-term stability, etc. The significantly improved gas sensing properties were mainly resulted from their high surface basicity, enriched defects (oxygen vacancies), small crystallite size and complex porous structures.