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2017-07-06 - Colloque/Présentation - communication orale - Anglais - 2 page(s)

Geng Xin, Zhang Chao, Olivier Marie-Georges , Debliquy Marc , "NO2 gas sensors based on suspension flame-sprayed oxygen vacant zinc oxide sensitive coatings on flexible polypropylene papers" in SMT31 - International Conference on Surface Modification Technologies, Mons, Belgique, 2017

  • Codes CREF : Capteurs et périphériques (DI2563), Matériaux optiques (DI1256)
  • Unités de recherche UMONS : Science des Matériaux (F502)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Ingénierie des matériaux (CRIM)

Abstract(s) :

(Anglais) 2D sheet-like oxygen-vacant zinc oxide (ZnO1-x) coatings composed of 0D nanoparticles were deposited on the flexible polypropylene papers equipped with gold electrodes in three steps. ZnO powder with sheet-like hierarchical structure was first synthesized by direct precipitation method. And then the as-synthesized powder was dispersed in anhydrous ethanol to form a suspension. At last, the suspension was injected into the acetylene-oxygen flame to deposit ZnO1-x sensitive layers with highly concentrated oxygen vacancies. X-ray diffraction and field-emission microscopy results confirmed that the as-sprayed coatings presented a hexagonal phase and exhibited a porous hierarchical structure. The characterization results indicated that spray distance had a significant influence on the microstructure and oxygen vacancy concentration. As the increase of spray distance, the as-sprayed coatings exhibited a morphology with smaller particle size and sheet thickness. Photoluminescence and X-ray photoelectron spectra tests indicated that large amounts of oxygen vacancies were introduced into as-sprayed coatings, and the oxygen vacancy concentration of the samples increased with the spray distance. Ultraviolet-Visible spectra revealed that the light absorption of the as-sprayed coatings was extended to visible light region, and wider absorption range was obtained when the spray distance was increased. The sensors using as-sprayed ZnO coatings as sensitive layers showed good response to sub-ppm level NO2 at room temperature under white light LED illumination. Compared with the coatings deposited by short spray distance, those with long spray distance having small particle size, broad visible light absorption range and high oxygen vacancy concentration, presented better NO2 sensing performance. All the results showed that introducing rich oxygen vacancies into ZnO is a good way to narrow down its bandgap, expand its visible light absorption and enhance the room temperature NO2 gas sensing performance. With the oxygen vacancy concentration increasing, the room temperature NO2 sensing properties of ZnO1-x with visible light stimulation will be better.