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Article

CuWO4 with CuO and Cu(OH)2 Native Surface Layers for H2S Detection under in-Field Conditions

1
“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021 Bucharest, Romania
2
National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
*
Author to whom correspondence should be addressed.
Materials 2021, 14(2), 465; https://doi.org/10.3390/ma14020465
Received: 16 November 2020 / Revised: 7 January 2021 / Accepted: 15 January 2021 / Published: 19 January 2021
(This article belongs to the Special Issue Advanced Materials for Gas Sensors)
The paper presents the possibility of detecting low H2S concentrations using CuWO4. The applicative challenge was to obtain sensitivity, selectivity, short response time, and full recovery at a low operating temperature under in-field atmosphere, which means variable relative humidity (%RH). Three different chemical synthesis routes were used for obtaining the samples labeled as: CuW1, CuW2, and CuW3. The materials have been fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). While CuWO4 is the common main phase with triclinic symmetry, different native layers of CuO and Cu(OH)2 have been identified on top of the surfaces. The differences induced into their structural, morphological, and surface chemistry revealed different degrees of surface hydroxylation. Knowing the poisonous effect of H2S, the sensing properties evaluation allowed the CuW2 selection based on its specific surface recovery upon gas exposure. Simultaneous electrical resistance and work function measurements confirmed the weak influence of moisture over the sensing properties of CuW2, due to the pronounced Cu(OH)2 native surface layer, as shown by XPS investigations. Moreover, the experimental results obtained at 150 °C highlight the linear sensor signal for CuW2 in the range of 1 to 10 ppm H2S concentrations and a pronounced selectivity towards CO, CH4, NH3, SO2, and NO2. Therefore, the applicative potential deserves to be noted. The study has been completed by a theoretical approach aiming to link the experimental findings with the CuW2 intrinsic properties. View Full-Text
Keywords: CuWO4; surface hydroxylation; selective sensitivity to H2S; applicative potential under in-field conditions; theoretical approach CuWO4; surface hydroxylation; selective sensitivity to H2S; applicative potential under in-field conditions; theoretical approach
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MDPI and ACS Style

Somacescu, S.; Stanoiu, A.; Dinu, I.V.; Calderon-Moreno, J.M.; Florea, O.G.; Florea, M.; Osiceanu, P.; Simion, C.E. CuWO4 with CuO and Cu(OH)2 Native Surface Layers for H2S Detection under in-Field Conditions. Materials 2021, 14, 465. https://doi.org/10.3390/ma14020465

AMA Style

Somacescu S, Stanoiu A, Dinu IV, Calderon-Moreno JM, Florea OG, Florea M, Osiceanu P, Simion CE. CuWO4 with CuO and Cu(OH)2 Native Surface Layers for H2S Detection under in-Field Conditions. Materials. 2021; 14(2):465. https://doi.org/10.3390/ma14020465

Chicago/Turabian Style

Somacescu, Simona, Adelina Stanoiu, Ion Viorel Dinu, Jose Maria Calderon-Moreno, Ovidiu G. Florea, Mihaela Florea, Petre Osiceanu, and Cristian E. Simion. 2021. "CuWO4 with CuO and Cu(OH)2 Native Surface Layers for H2S Detection under in-Field Conditions" Materials 14, no. 2: 465. https://doi.org/10.3390/ma14020465

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