Use of nanostructured oxides for selective gas-sensing

Y. Gönüllü; B. Saruhan

doi:10.1117/12.2053000

4 June 2014 Use of nanostructured oxides for selective gas-sensing

Y. Gönüllü, B. Saruhan

Proceedings Volume 9083, Micro- and Nanotechnology Sensors, Systems, and Applications VI; 90830Z (2014) https://doi.org/10.1117/12.2053000
Event: SPIE Defense + Security, 2014, Baltimore, MD, United States

Abstract

Titania nanotubular layers (TiO₂-NTs) are better known with their use in dye-synthesized solar cells. In the field of gas sensors, the best known application of TiO₂-NT layers is given with H₂ sensing. TiO₂–NT structures are commonly synthesized from pure titanium by anodic oxidation method. As literature indicates, gas sensing with titania can be modified by doping to obtain p- or n-type semiconductor behaviour. As undoped titania is widely used for CO and H₂- sensing, Al- and Cr-doped titania is reported to be effective for NO₂-sensing. Nanostructuring of TiO₂ yields faster and more stable response toward CO and NO₂ with almost no drift in sensor signal. Dopants are introduced by wet-chemistry method or by simultaneous anodization in an alloy. We introduced Cr³⁺ to TiO₂ NT-layers by soaking in nitrate salt and Al³⁺ by anodization of Ti6Al4V alloy. All doped TiO₂ NTs are tested for NO₂ sensing at temperatures up to 500°C in the presence of CO. The characteristics of doping are investigated by XRD, EDX-TEM methods. Cr-doping of nanotubular TiO₂ sensors displays p-type semiconductor behaviour and a considerably increased NO₂-selectivity, while Aldoping emphasizes the CO-selectivity. Effect of Cr-doping on sensing is further investigated by means of impedance spectroscopic measurements and equivalent circuit modeling in order to optimize the sensors for real-time measurements.

Citation Download Citation

Y. Gönüllü and B. Saruhan "Use of nanostructured oxides for selective gas-sensing", Proc. SPIE 9083, Micro- and Nanotechnology Sensors, Systems, and Applications VI, 90830Z (4 June 2014); https://doi.org/10.1117/12.2053000

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