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. 2022 Dec 14;7(51):47796-47805.
doi: 10.1021/acsomega.2c05589. eCollection 2022 Dec 27.

Facile Synthesis of Pure and Cr-Doped WO3 Thin Films for the Detection of Xylene at Room Temperature

Srinivasa Rao Sriram  1 , Saidi Reddy Parne  1 , Nagaraju Pothukanuri  2   3 , Dhananjay Joshi  4 , Damodar Reddy Edla  5
Affiliations

Facile Synthesis of Pure and Cr-Doped WO3 Thin Films for the Detection of Xylene at Room Temperature

Srinivasa Rao Sriram et al. ACS Omega. .

Abstract

This paper focused on the preparation of pure and Cr-doped tungsten trioxide (WO3) thin films using the spray pyrolysis method. Different techniques were adopted to analyze these films' structural and morphological properties. The X-ray detection analysis showed that the average crystallite size of the WO3-nanostructured thin films increased as the Cr doping concentration increased. The atomic force microscopy results showed that the root-mean-square roughness of the films increased with Cr doping concentration up to 3 wt % and then decreased. The increased roughness is favorable for gas-sensing applications. Surface morphology and elemental analysis of the films were studied by field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy measurements. The 3 wt % Cr-WO3 has a large nanoflake-like structure with high surface roughness and porous morphology. Gas-sensing characteristics of undoped and Cr-doped WO3 thin films were investigated with various gases at room temperature. The results showed that 3 wt % Cr-doped WO3 film performed the maximum response toward 50 ppm of xylene with excellent selectivity at room temperature. We believe that increased lattice defects, surface morphology, and roughness due to Cr doping in the WO3 crystal matrix might be responsible for increased xylene sensitivity.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Essential components in the gas testing experiment setup.
Figure 2
Figure 2
XRD patterns of pure and Cr-doped WO3 thin films.
Figure 3
Figure 3
Raman spectra of pure and Cr-doped WO3 thin films.
Figure 4
Figure 4
FESEM images of (a) pure WO3, (b) 1 wt % Cr-doped WO3, (c) 3 wt % Cr-doped WO3, and (d) 5 wt % Cr-doped WO3.
Figure 5
Figure 5
Energy-dispersive X-ray spectroscopy (EDX) spectra of the WO3-based thin films.
Figure 6
Figure 6
AFM pictures of (a) pure WO3, (b) 1 wt % Cr-doped WO3, (c) 3 wt % Cr-doped WO3, and (d) 5 wt % Cr-doped WO3.
Figure 7
Figure 7
Response of pure and Cr-doped WO3 films with various concentrations of xylene.
Figure 8
Figure 8
(a) Repeatability and (b) long-term stability for 50 ppm xylene gas of the 3 wt % Cr-WO3 sensor.
Figure 9
Figure 9
Systematic representation of the sensing mechanism.
Figure 10
Figure 10
Selectivity of Cr-doped WO3 films toward certain gases.
Figure 11
Figure 11
Transient response curve of the 3 wt % Cr-doped WO3-based sensor response toward 50 ppm of xylene.
Figure 12
Figure 12
Dynamic response curve of the 3 wt % Cr-doped WO3-based sensor.
See this image and copyright information in PMC

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