Si doped highly crystalline mesoporous In2O3 nanowires: synthesis, characterization and ultra-high response to NOx at room temperatureElectronic supplementary information (ESI) available. See DOI: 10.1039/c4ra14354j

• Main Authors: Yao, Liyuan, Kan, Kan, Lin, Yufei, Song, Jiabao, Wang, Jingchao, Gao, Jun, Shen, Peikang, Li, Li, Shi, Keying
• Format: Journal Article
• Language: English
• Published: 03.02.2015
• ISSN: 2046-2069
• DOI: 10.1039/c4ra14354j

1D highly crystalline mesoporous In 2 O 3 nanowires (INWs) coated by an amorphous silica (HCMIAS) ultrathin surface layer were successfully fabricated using SBA-16 as a hard template. Various techniques, including XRD, SEM, TEM and X-ray photoelectron spectroscopy (XPS), were employed for material characterization. All the results demonstrated that the obtained INW-2 sample, which contained 15 at% SiO 2 and 85 at% In 2 O 3 in 0.2 M In(NO 3 ) 3 solution, displayed high crystallinity with a rough surface coating layer of SiO 2 in the atomic scale. The domain diameter of INW-2 was approximately 4-8 nm with the pore size of 3-5 nm. The NO x sensing properties of the INW-2 sensor exhibited an ultra-high response and selectivity with the low detection limit of 0.97 ppm and high response of 115.6 to 97.0 ppm NO x at RT. The excellent gas sensing property of the 1D morphology with amorphous silica was associated with its higher surface area and space-charge layer, which induced highly effective surface interactions between the target gas molecules and the surface active sites. Moreover, the synergetic and electronic effect on INW-2 favored the effective adsorption of NO x on the surface. All the factors considered had evident beneficial effects on enhancing the gas sensing performance of the sensor. The synthesized INW-2 has an ultrathin surface layer and high density defects. The special structure offers available active centers for gas/surface reactions. INW-2 sensor possesses the ultrahigh response and selectivity to NO x at room temperature.