Synthesis of the PS/CdSeNRs composite for room temperature NO 2 gas sensing
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ORIGINAL PAPER
Synthesis of the PS/CdSeNRs composite for room temperature NO2 gas sensing Fakher Laatar 1,2 Received: 1 May 2020 / Revised: 5 August 2020 / Accepted: 10 August 2020 # Springer Nature B.V. 2020
Abstract In the present work, the cadmium selenide nanorods (CdSeNRs) have been successfully synthesized onto porous silicon (PS) layer via hydrothermal method. The structural and surface morphology of PS/CdSeNRs composite were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The CdSeNRs were homogeneously distributed at the PS surface with the presence of some microvoids, which contributes to the adsorption/desorption process of NO2 gas molecules. At the optimum working temperature (25 °C), the PS/CdSeNRs composite showed greater gas response than that of the PS layer at 1 ppm NO2. Simultaneously, the PS/CdSe composite sensor displayed high gas response, excellent repeatability and perfect stability toward NO2 gas owing to its large specific surface area, particular structure, and great amounts of oxygen vacancies. The weak responses of the composite sensor to great concentrations of other reducing gases indicate an excellent selectivity to NO2 gas. Keywords PS . CdSeNRs . Hydrothermal synthesis . NO2 gas sensor . Room temperature
1 Introduction The raise in exhaust gas emissions percentage put a great demand on the sensitive and selective detection of dangerous gases for monitoring environmental pollution and maintaining safety and human health [1]. Nitrogen dioxide NO2 is a very toxic gas that can give rise to breathing problems and generation of acid rain and mist [2, 3], hence the ability to monitor NO2 concentrations in air with precision is an absolute necessity. A variety of semiconducting materials nanostructures, such as CdS [4], CdS QDs/ZnO [5], CdSe QDs sensitized MOx [6], CdSe/PAA [7], CdSe/p-polyaniline [8], and CdSe/SiO2 [9] have been extensively used as gas sensor. Among them, cadmium selenide (CdSe) is considered to be a promising compound for NO2sensing. Several studies have proved that CdSe nanostructures are suitable candidates for NO2-sensing due to their high crystallinity and broad specific surface area [6]. However, CdSe sensors need
* Fakher Laatar [email protected]; [email protected] 1
Department of Physics, College of Science and Humanities Studies of Afif, Afif Governorate, Shaqra University, Shaqraa, Saudi Arabia
2
Laboratory of Semiconductors, Nanostructures and Advanced Technology (LSNTA), Research and Technology Center of Energy (CRTEn), BP95, Hammam-Lif 2050, Tunisia
extremely high operating temperatures for interacting with gas molecules [5, 7]. The great working temperature is inappropriate for power consuming and devices integration. Consequently, many researchers have been obliged to reduce the working temperature of CdSe sensors [5, 6]. PS is also a promising semiconductor, which has been broadly used as substrate of composites gas sensors or directly as gas sensor
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