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Identifier

000416611

Title

Study of toxic gases by using n- and p- type composite material

Alternative Title

Μελέτη της ανίχνευσης τοξικών αερίων με χρήση n- και p- τύπου σύνθετων υλικών

Author

Μοσχογιαννάκη, Μαριλένα Μ.

Thesis advisor

Τσιρώνης, Γεώργιος

Reviewer

Κυριακίδης, Γεώργιος
Ρεμεδιάκης, Ιωάννης
Μπίνας, Βασίλειος

Abstract

In my master thesis work, two series of oxide cpmposites were synthesized, characterized and studied for gas sensing applications, namely; Nickel-Cobalt Vanadates (Ni V₂O₆, Co_0.5Ni_0.5 V₂O₆and Co V₂O₆) and Nickel-Cobalt Tungstates (NiWO₂, Co_0.5Ni_0.5WO₄ and CoWO₄). The Vanadates were obtained by an easy and low cost solution based synthetic procedure in which ethylene-glycol was used as a ligand. Tungstates were synthesized with the hydrothermal process. Calcined powders of both series were characterized by X-Ray Powder Diffractometry and Scanning Electron Microscopy. Tungstates were studied in 4 different gases from toxic to flammable gases such as H₂, H₂S, NO and acetone. The sensing films were prepared by the spin-coating technique and their gas-sensing performances were studied at operating temperatures ranging from 200 to 350 ^oC in dry air. The Tungstate sensors (n-type) exhibit low response in these gases and due to the short time of the thesis, they were not studied further. The Vanadate Oxides were also tested in these 4 gases and the Co_0.5Ni_0.5V₂O₆ and Co V₂O₆ sensors exhibit the highest response at 300 ^oC in H₂ gas, namely 11 and 16 respectively. p-type Co V₂O₆ nanoparticles were selected and were loaded with 0-2 wt% Palladium (Pd) and systematically investigated for H₂- sensing applications. Gas sensing measurements showed that Co V₂O₆ sensing film with the optimal Pd-loading level of 1wt% exhibited a high response of ~114, which was one order of magnitude higher than that of undoped one, and a short response time of 17s towards 30.000 ppm H2 at an optimum operating temperature of 300 ^oC. In addition, the optimal Pd-loaded Co V₂O₆ sensor displayed high H2 selectivity against NO, NO2, H2S and acetone. Thus, Pd- loaded CoV₂O₆ nanoparticle thick films were proved promising candidates for H₂-sensing applications.

Language

English

Subject

Composite material

Gas sensing

Gas sensors

Metal oxides

Αισθητήρες αερίων

Ανίχνευση αερίων

Οξείδια μετάλλων

Σύνθετα υλικά

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