13 research outputs found

    Electrochromism of non-stoichiometric NiO thin film: as single layer and in full device

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    Electrochromic properties, known as a reversible modulation of the optical properties under an applied voltage, of NiO thin films are discussed in respect of the film stoichiometry. Using radio-frequency magnetron sputtering, non-stoichiometric "NiO" thin films of good crystallinity were grown at room temperature from low oxygen partial pressure [i.e., above 2 % P(O2/Ar + O2)]. A further increase in oxygen partial pressure leads to conductive brownish films containing a large amount of Ni3+. 2 %-Ni1- x O thin films exhibit significant EC performance in lithium-based electrolyte with a transmittance modulation of 25 %. If it is generally accepted that this optical modulation is due to an insertion of small cations, the presence of additional surface phenomena is also shown. The cycling of full device, based on the association of WO3 and "NiO" in temperature up to 60 °C and down to -35 °C confirms expected increase and decrease in capacity while surprisingly the optical switch from a transparent to a neutral gray color appears slightly modified

    Highly Sensitive NiO Nanoparticle based Chlorine Gas Sensor

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    We have synthesized a chemiresistive sensor for chlorine (Cl-2) gas in the range of 2-200 ppm based on nickel oxide (NiO) nanoparticles obtained by wet chemical synthesis. The nanoparticles were characterized by x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence (PL) spectroscopy. XRD spectra of the sensing layer revealed the cubic phase of NiO nanoparticles. The NiO nanoparticle size was calculated to be similar to 21 nm using a Williamson-Hall plot. The bandgap of the NiO nanoparticles was found to be 3.13 eV using Tauc plots of the absorbance curve. Fast response time (12 s) and optimum recovery time (similar to 27 s) were observed for 10 ppm Cl-2 gas at moderate temperature of 200A degrees C. These results demonstrate the potential application of NiO nanoparticles for fabrication of highly sensitive and selective sensors for Cl-2 gas
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