Cargando…

Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures

Here, we show that the presence of adsorbed water improves the oxygen-sensing properties of Pt/TiO [Formula: see text] at moderate temperatures. The studied interface is based on porous plasma electrolytic oxidized titanium (PEO-TiO [Formula: see text]) covered with platinum clusters. The electrical...

Descripción completa

Detalles Bibliográficos
Autores principales: Engelkamp, Bernd, Schierbaum, Klaus
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8038718/
https://www.ncbi.nlm.nih.gov/pubmed/33917432
http://dx.doi.org/10.3390/s21072558
_version_ 1783677440258736128
author Engelkamp, Bernd
Schierbaum, Klaus
author_facet Engelkamp, Bernd
Schierbaum, Klaus
author_sort Engelkamp, Bernd
collection PubMed
description Here, we show that the presence of adsorbed water improves the oxygen-sensing properties of Pt/TiO [Formula: see text] at moderate temperatures. The studied interface is based on porous plasma electrolytic oxidized titanium (PEO-TiO [Formula: see text]) covered with platinum clusters. The electrical resistance across Pt/PEO-TiO [Formula: see text] is explained by an electronic depletion layer. Oxygen adsorbates further increase the depletion by inducing extrinsic interface states, which are occupied by TiO [Formula: see text] conduction band electrons. The high oxygen partial pressure in ambient air substantially limits the electron transport across the interface. Our DC measurements at defined levels of humidity at 30 [Formula: see text] C show that adsorbed water counteracts this shortcoming, allowing oxygen sensing at room conditions. In addition, response and recovery times from temporal oxygen exposure decrease with humidity. We attribute the effects to competing adsorption processes and reactions of water with adsorbed oxygen species and/or lattice oxygen, which involve electron re-injection to the TiO [Formula: see text] conduction band. Elevated temperatures up to 170 [Formula: see text] attenuate the effects, presumably due to the lower binding strength to the surface of molecular water compared with oxygen adsorbates.
format Online
Article
Text
id pubmed-8038718
institution National Center for Biotechnology Information
language English
publishDate 2021
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-80387182021-04-12 Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures Engelkamp, Bernd Schierbaum, Klaus Sensors (Basel) Article Here, we show that the presence of adsorbed water improves the oxygen-sensing properties of Pt/TiO [Formula: see text] at moderate temperatures. The studied interface is based on porous plasma electrolytic oxidized titanium (PEO-TiO [Formula: see text]) covered with platinum clusters. The electrical resistance across Pt/PEO-TiO [Formula: see text] is explained by an electronic depletion layer. Oxygen adsorbates further increase the depletion by inducing extrinsic interface states, which are occupied by TiO [Formula: see text] conduction band electrons. The high oxygen partial pressure in ambient air substantially limits the electron transport across the interface. Our DC measurements at defined levels of humidity at 30 [Formula: see text] C show that adsorbed water counteracts this shortcoming, allowing oxygen sensing at room conditions. In addition, response and recovery times from temporal oxygen exposure decrease with humidity. We attribute the effects to competing adsorption processes and reactions of water with adsorbed oxygen species and/or lattice oxygen, which involve electron re-injection to the TiO [Formula: see text] conduction band. Elevated temperatures up to 170 [Formula: see text] attenuate the effects, presumably due to the lower binding strength to the surface of molecular water compared with oxygen adsorbates. MDPI 2021-04-06 /pmc/articles/PMC8038718/ /pubmed/33917432 http://dx.doi.org/10.3390/s21072558 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Engelkamp, Bernd
Schierbaum, Klaus
Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures
title Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures
title_full Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures
title_fullStr Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures
title_full_unstemmed Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures
title_short Oxygen Sensing of Pt/PEO-TiO(2) in Humid Atmospheres at Moderate Temperatures
title_sort oxygen sensing of pt/peo-tio(2) in humid atmospheres at moderate temperatures
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8038718/
https://www.ncbi.nlm.nih.gov/pubmed/33917432
http://dx.doi.org/10.3390/s21072558
work_keys_str_mv AT engelkampbernd oxygensensingofptpeotio2inhumidatmospheresatmoderatetemperatures
AT schierbaumklaus oxygensensingofptpeotio2inhumidatmospheresatmoderatetemperatures