Preeti Kaushik, Marek Eliáš, Jan Prášek, Jan Michalička, Lenka Zajíčková

Manipulating MWCNT/TiO2 heterostructure morphology at nanoscale and its implications to NO2 sensing properties

Materials Chemistry and Physics 271 (2021) 124901

Multi-walled carbon nanotubes (MWCNTs) based heterostructures were prepared by oxygen plasma treatment and atomic layer deposition (ALD) of TiO₂ carried on MWCNTs. Different TiO₂ structures (island, granular and continuous forms) on the nanotubes were obtained by varying the processing parameters. Chemical inertness of MWCNTs led to the ALD of TiO₂ in an island form. Oxygen plasma treatment ensured deposition of a continuous TiO₂ film, 5 nm in thickness. A granular form of TiO₂ was obtained on oxygen plasma treated MWCNTs using shorter duration of Ti-precursor pulse. Different imaging modes in high resolution transmission electron mi­ croscopy visualized TiO₂ nanostructures and defects in MWCNT walls. The latter were also confirmed by Raman spectroscopy. The morphology of TiO₂ and oxygen plasma treatment of the MWCNTs highly affected the NO₂ sensing behavior of chemiresistive heterostructure sensors at room and elevated temperatures. All investigated sensors exhibited a decrease in the resistance upon exposure to NO2 gas which implies a p-type sensor response. The granular TiO₂/MWCNTs heterostructure showed the highest response towards NO2 gas as compared to the island and continuous forms.

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DOI: 10.1016/j.matchemphys.2021.124901

You can also contact one of the authors: mareke@physics.muni.cz, lenkaz@physics.muni.cz