Sol-gel TiO2 films as NO2 gas sensors

18th International Summer School on Vacuum, Electron and Ion Technologies

Georgieva, V.^1 ; Gadjanova, V.^1 ; Grechnikov, A.^2 ; Donkov, N.^3 ; Sendova-Vassileva, M.^4 ; Stefanov, P.^5 ; Kirilov, R.^4

Acad. G. Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria^1

Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin Str., 119991 Moscow, Russia^2

Acad. E. Djakov Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria^3

Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria^4

Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia, Bulgaria^5

关键词: Adsorption/desorption;    Process parameters;    Quartz crystal microbalance techniques;    Resonant frequency shift;    Sauerbrey equation;    Sensing characteristics;    Special treatments;    Time characteristics;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/514/1/012020/pdf
DOI  :  10.1088/1742-6596/514/1/012020

来源: IOP

【 摘 要 】

TiO2films were prepared by a sol-gel technique with commercial TiO2powder as a source material (P25 Degussa AG). After a special treatment, printing paste was prepared. The TiO2layers were formed by means of drop-coating on Si-control wafers and on the Au-electrodes of quartz resonators. The surface morphology of the films was examined by scanning electron microscopy (SEM). Their structure was studied by Raman spectroscopy and the surface composition was determined by X-ray photoelectron spectroscopy (XPS). The layers had a grain-like surface morphology and consisted mainly of anatase TiO2phase. The sensitivity of the TiO2films to NO2was assessed by the quartz crystal microbalance (QCM) technique. To this end, the films were deposited on both sides of a 16-MHz QCM. The sensing characteristic of the TiO2-QCMstructure was investigated by measuring the resonant frequency shift (ΔF) of the QCM due to the mass loading caused by NO2adsorption. The Sauerbrey equation was applied to establish the correlation between the QCM frequency changes measured after exposure to different NO2concentrations and the mass-loading of the QCM. The experiments were carried out in a dynamic mode on a special laboratory setup with complete control of the process parameters. The TiO2films were tested in the NO2concentration interval from 10 ppm to 5000 ppm. It was found that a TiO2loading of the QCM by 5.76 kHz corresponded to a system sensitive to NO2concentrations above 250 ppm. On the basis of the frequency-time characteristics (FTCs) measured, AF at different NO2concentrations was defined, the adsorption/desorption cycles were studied and the response and recovery times were estimated. The results obtained show that the process is reversible in the NO2interval investigated. The results further suggested that TiO2films prepared by a sol-gel method on a QCM can be used as a sensor element for NO2detection.