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Influence of Humidity on NO2-Sensing and Selectivity of Spray-CVD Grown ZnO Thin Film above 400 ◦C

Lontio Fomekong, Roussin and Saruhan-Brings, Bilge (2019) Influence of Humidity on NO2-Sensing and Selectivity of Spray-CVD Grown ZnO Thin Film above 400 ◦C. Chemosensors, 7 (3), pp. 42-54. Multidisciplinary Digital Publishing Institute (MDPI). doi: 10.3390/chemosensors7030042. ISSN 2227-9040.

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Abstract

Thin films are being used more and more in gas sensing applications, relying on their high surface area to volume ratio. In this study, ZnO thin film was produced through a thermal aerosol spraying and chemical vapor deposition (spray-CVD) process at 500 °C using zinc acetate as a precursor. The phase identification and the morphologies of the film were investigated by XRD and SEM, respectively. Gas-sensing properties of the ZnO thin film were evaluated toward NO2, CO, and NO at a moderate temperature range (400–500 °C) in dry and humid air (relative humidity = 2.5, 5, 7.5, and 10% RH). The obtained results show good sensor signal for both NO2 (ΔR/R0 = 94%) and CO (92%) and poor sensor signal to NO (52%) at an optimum temperature of 450 °C in dry air. The response and recovery times decrease with the increase of NO2 concentration. In the presence of humidity (10% of RH), the sensor is more than twice as sensitive to NO2 (70%) as CO (29%), and accordingly, exhibits good selectivity toward NO2. As the amount of humidity increases from 2.5 to 10% RH, the selectivity ratio of ZnO thin film to NO2 against CO increases from 1 to 2.4. It was also observed that the response and the recovery rates decrease with the increase of relative humidity. The significant enhancement of the selectivity of ZnO thin film toward NO2 in the presence of humidity was attributed to the strong affinity of OH species with NO2.

Item URL in elib:https://elib.dlr.de/129536/
Document Type:Article
Title:Influence of Humidity on NO2-Sensing and Selectivity of Spray-CVD Grown ZnO Thin Film above 400 ◦C
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Lontio Fomekong, RoussinRoussin.LontioFomekong (at) dlr.deUNSPECIFIED
Saruhan-Brings, BilgeBilge.Saruhan (at) dlr.deUNSPECIFIED
Date:4 September 2019
Journal or Publication Title:Chemosensors
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:7
DOI :10.3390/chemosensors7030042
Page Range:pp. 42-54
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
ISSN:2227-9040
Status:Published
Keywords:Gas sensor, ZnO, SprayCVD, thin film
HGF - Research field:Energy
HGF - Program:Energy Efficiency, Materials and Resources
HGF - Program Themes:Efficient and Flexible Power Plants
DLR - Research area:Energy
DLR - Program:E VS - Combustion Systems
DLR - Research theme (Project):E - Gas Turbine (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > High Temperature and Functional Coatings
Deposited By: Saruhan-Brings, Dr. Bilge
Deposited On:06 Nov 2019 16:06
Last Modified:20 Jan 2020 09:58

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