Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Dec 5;20(23):6951.
doi: 10.3390/s20236951.

Correlation between Microstructure and Chemical Composition of Zinc Oxide Gas Sensor Layers and Their Gas-Sensitive Properties in Chlorine Atmosphere

Marta Fiedot-Toboła  1   2 , Patrycja Suchorska-Woźniak  1 , Kamila Startek  2 , Olga Rac-Rumijowska  1 , Rafał Szukiewicz  2   3 , Monika Kwoka  4 , Helena Teterycz  1
Affiliations

Correlation between Microstructure and Chemical Composition of Zinc Oxide Gas Sensor Layers and Their Gas-Sensitive Properties in Chlorine Atmosphere

Marta Fiedot-Toboła et al. Sensors (Basel). .

Abstract

In this article, we present results concerning the impact of structural and chemical properties of zinc oxide in various morphological forms and its gas-sensitive properties, tested in an atmosphere containing a very aggressive gas such as chlorine. The aim of this research was to understand the mechanism of chlorine detection using a resistive gas sensor with an active layer made of zinc oxide with a different structure and morphology. Two types of ZnO sensor layers obtained by two different technological methods were used in sensor construction. Their morphology, crystal structure, specific surface area, porosity, surface chemistry and structural defects were characterized, and then compared with gas-sensitive properties in a chlorine-containing atmosphere. To achieve this goal, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL) methods were used. The sensing properties of obtained active layers were tested by the temperature stimulated conductance method (TSC). We have noticed that their response in a chlorine atmosphere is not determined by the size of the specific surface or porosity. The obtained results showed that the structural defects of ZnO crystals play the most important role in chlorine detection. We demonstrated that Cl2 adsorption is a concurrent process to oxygen adsorption. Both of them occur on the same active species (oxygen vacancies). Their concentration is higher on the side planes of the zinc oxide crystal than the others. Additionally, ZnO sublimation process plays an important role in the chlorine detection mechanism.

Keywords: chemistry; chlorine sensitivity; microstructure; resistive gas sensors; zinc oxide.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Images of the gas sensor surface from the side of: (a) gold electrodes and (b) platinum heater.
Figure 2
Figure 2
SEM images of ZnO layers formed with the method: (a) screen printing; (b) chemical bath deposition (CBD).
Figure 3
Figure 3
X-ray diffraction patterns of obtained ZnO layers (JCPDS 5-0664).
Figure 4
Figure 4
Isotherms of N2 adsorption/desorption and Brunauer–Emmett–Teller (BET) analysis results of the samples.
Figure 5
Figure 5
Zinc oxide XPS spectra in the form of: (a) powder; (b) microrods.
Figure 6
Figure 6
XPS O1s spectral lines after deconvolution of ZnO: (a) powder, (b) microrods.
Figure 7
Figure 7
Photoluminescence (PL) spectra of ZnO samples.
Figure 8
Figure 8
Temperature changes of: (a) conductance; (b) sensitivity to Cl2 of the sensors.
Figure 9
Figure 9
Diagram of the chemical sorption process of oxygen on the surface of an n-type oxide semiconductor.
Figure 10
Figure 10
Sensitivity simulation to 2 ppm Cl2 as a function of temperature of: (a) powder and (b) microrods.
Figure 11
Figure 11
Changes of oxygen partial pressure on the ZnO surface [64] and sensitivity in an atmosphere containing chlorine: (a) layer of ZnO microrods, (b) layer made by screen printing. I—oxygen chemisorption combined with charge exchange with ZnO. II—desorption of chemisorbed oxygen bound to the ZnO surface. III—sublimation of highly defective zinc oxide.
Figure 12
Figure 12
Scheme of chlorine detection steps on ZnO surfaces: (a) O2 chemisorption, (b) partial O2 desorption and Cl2 adsorption, (c) sublimation of ZnO. LD—Debye length, EC—Conduction band energy, EF—Fermi level and EV—Valence band energy.
See this image and copyright information in PMC

References

    1. Williams D.E. Semiconducting oxides as gas-sensitive resistors. Sens. Actuators B Chem. 1999;57:1–16. doi: 10.1016/S0925-4005(99)00133-1. - DOI
    1. Urasinska-Wojcik B., Vincent T.A., Chowdhury M.F., Gardner J.W. Ultrasensitive WO3 gas sensors for NO2 detection in air and low oxygen environment. Sens. Actuators B Chem. 2017;239:1051–1059. doi: 10.1016/j.snb.2016.08.080. - DOI
    1. Wei H.L., Kumar P., Yao D.J. Printed Resistive Sensor Array Combined with a Flexible Substrate for Ethanol and Methane Detection. ECS J. Solid State Sci. Technol. 2020:115008. doi: 10.1149/2162-8777/ab9fe6. - DOI
    1. Xia Y., Wang J., Xu L., Li X., Huang S. A room-temperature methane sensor based on Pd-decorated ZnO/rGO hybrids enhanced by visible light photocatalysis. Sens. Actuators B Chem. 2020;304:127334. doi: 10.1016/j.snb.2019.127334. - DOI
    1. Latyshev V.M., Berestok T.O., Opanasyuk A.S., Kornyushchenko A.S., Perekrestov V.I. Nanostructured ZnO films for potential use in LPG gas sensors. Solid State Sci. 2017;67:109–113. doi: 10.1016/j.solidstatesciences.2017.02.010. - DOI

LinkOut - more resources