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We studied the photocatalytic and electrochemical impedance properties of two different sub-stoichiometric titania powders deposited using plasma spraying. Two different commercial powders with markedly diverse mean size as well as size distribution were chosen. Thermal oxidation of these as-received powders was carried out to restore the O/Ti ratio to be 2.0. By this way, another two kinds of feedstock powders were obtained. Total of four kinds of feedstock powders were used in the experiments. All powders were sprayed using identical plasma spraying parameters. For some spraying runs, carbon steel served as the substrate, and for others, the previously sprayed titania coating from a different kind of feedstock. Combinations of single- and double-layer coatings were studied. Porosity, microstructure, phase composition, chemical composition, band gap based on reflectance measurement, and photocatalytic activity were examined. Electrochemical impedance spectroscopy demonstrated substantial differences between samples sprayed from the fine and coarse powders. Coatings from oxidized powders were slightly more photocatalytic. High spraying distance used for several of them was good for obtaining low band gap, whereas surface roughness and phase composition were not substantially different compared to standard spraying distance coatings.


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Photocatalytic and electrochemical properties of single- and multi-layer sub-stoichiometric titanium oxide coatings prepared by atmospheric plasma spraying

Show Author's information Pavel CTIBORa( )Ramachandran Chidambaram SESHADRIbJiri HENYCHcVaclav NEHASILdZdenek PALAaJiri KOTLANa
Materials Engineering Department, Institute of Plasma Physics AS CR, Za Slovankou 3, Prague 8, Czech Republic
Center for Thermal Spray Research, Department of Materials Science & Engineering, The State University of New York at Stony Brook, NY 11794-2275, USA
Institute of Inorganic Chemistry AS CR, Husinec-Rez 250 68, Czech Republic
Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, Prague 8, Czech Republic

Abstract

We studied the photocatalytic and electrochemical impedance properties of two different sub-stoichiometric titania powders deposited using plasma spraying. Two different commercial powders with markedly diverse mean size as well as size distribution were chosen. Thermal oxidation of these as-received powders was carried out to restore the O/Ti ratio to be 2.0. By this way, another two kinds of feedstock powders were obtained. Total of four kinds of feedstock powders were used in the experiments. All powders were sprayed using identical plasma spraying parameters. For some spraying runs, carbon steel served as the substrate, and for others, the previously sprayed titania coating from a different kind of feedstock. Combinations of single- and double-layer coatings were studied. Porosity, microstructure, phase composition, chemical composition, band gap based on reflectance measurement, and photocatalytic activity were examined. Electrochemical impedance spectroscopy demonstrated substantial differences between samples sprayed from the fine and coarse powders. Coatings from oxidized powders were slightly more photocatalytic. High spraying distance used for several of them was good for obtaining low band gap, whereas surface roughness and phase composition were not substantially different compared to standard spraying distance coatings.

Keywords:

titanium dioxide, stoichiometry, feedstock, photocatalysis, spectroscopic techniques
Received: 14 December 2015 Revised: 21 January 2016 Accepted: 22 January 2016 Published: 12 May 2016 Issue date: June 2021
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Publication history
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Publication history

Received: 14 December 2015
Revised: 21 January 2016
Accepted: 22 January 2016
Published: 12 May 2016
Issue date: June 2021

Copyright

© The author(s) 2016

Acknowledgements

The authors thank to Prof. S. Sampath, State University of New York at Stony Brook, for allowing the access to the thermal spray facility of CTS and for fruitful discussions on the experiments. The authors also thank to Dr. I. Beshajova, Faculty of Electrical Engineering, CTU Prague, for assistance at EDS measurement.

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