Browsing by Author "Abdelkader Djelloul 2"
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Item A simple synthesis of CuO NPs for photocatalytic applications and theirs structural and optical properties.(Journal of New Technology and Materials, 2021-10-24) Sabrina Roguai 1; Abdelkader Djelloul 2In this study, the copper nanoparticles were synthesized by simple co-precipitation method which were obtained by heating at 80°C for photocatalytic application. The microstructural characterization of the nanopowder obtained was performed using X-ray diffraction (XRD), SEM, EDS, and Infrared Spectroscopy (IR). The optical properties of nanoparticles were studied by UV-Visible spectroscopy. XRD studies demonstrated that the formation of CuO monoclinic phase and the average grain size of CuO crystallite were found to be 30 nm. The FTIR spectral analysis showed the characteristics peaks of Cu-O bond. The EDAX result indicated that there were no other elemental impurities present in the prepared CuO nanoparticles. SEM images indicate the morphology as a three-dimensional flower-like structure was successfully prepared for subsequent degradation of methylene blue (MB). With regard to the optical proprieties, the value of the bandgap energy equals 1.34 eV.Item A structural and optical properties of Cu‑doped ZnO flms prepared by spray pyrolysis(Applied Physics A, Springer-Verlag GmbH Germany, part of Springer Nature 2019, 2020-01-23) Sabrina Roguai 1; Abdelkader Djelloul 2Pure and Cu doped ZnO flms were grown by ultrasonic spray pyrolysis onto glass substrates at 450 °C for 30 min. This study aims to investigate the infuence of Cu doping content [0.02–0.20] on structural, microstructural and optical proper ties. X-ray difraction analysis reveals a structural disorder depending on Cu loading besides the appearance of CuO phase. The doping efectiveness is revealed by EDX analysis of the chemical composition of the flms. The transmittance shows a decreasing tendency with increasing Cu concentration. The refractive indices increase, whereas the values of forbidden energy gap decrease with the increase in Cu dopant concentrationItem A structural and optical properties of Cu‑doped ZnO flms prepared by spray pyrolysis(Applied Physics A, Springer-Verlag GmbH Germany, part of Springer Nature 2019, 2020-01-23) Sabrina Roguai 1; Abdelkader Djelloul 2Pure and Cu doped ZnO flms were grown by ultrasonic spray pyrolysis onto glass substrates at 450 °C for 30 min. This study aims to investigate the infuence of Cu doping content [0.02–0.20] on structural, microstructural and optical proper ties. X-ray difraction analysis reveals a structural disorder depending on Cu loading besides the appearance of CuO phase. The doping efectiveness is revealed by EDX analysis of the chemical composition of the flms. The transmittance shows a decreasing tendency with increasing Cu concentration. The refractive indices increase, whereas the values of forbidden energy gap decrease with the increase in Cu dopant concentration.Item determination of optical constants from transmittance data of co-doped Zn0.90Co0.05M0.05O (Mdouble bondAl, Cu, Cd, Na) films(Journal of Alloys and Compounds, Elsevier Ltd, 2014-02-24) Sabrina Roguai 1; Abdelkader Djelloul 2; Corinne Nouveau 3; T. Souier 4; A.A. Dakhel 5; M. Bououdina 6ZnO, Zn0.95Co0.05O and Zn0.90Co0.05M0.05O (M@Al, Cd, Na, Cu) single phase films have been successfully synthesized by ultrasonic spray pyrolysis technique. Structural analysis by X-ray diffraction show that all the films have hexagonal wurtzite structure with an average crystallite size in the range of 19–25 nm. SEM analysis revealed that Cd and Na preserve the shape of nanopetals observed with ZnO or CoAZnO films, while the doping with Al or Cu promote the formation of dense films constituted of nanorods. By the application of Levenberg–Marquardt least square method, the experimental transmit tance data were fitted perfectly with the transmittance data calculated via a combination of Wemple– DiDomenico model, absorption coefficient of an electronic transition and Tauc–Urbach model. The concentration of absorbing centres NCo and oscillator strength f of d–d transition of Co2+ ions are calculated from Smakula’s formulaItem Elaboration, characterization and applications of SnO2, 2 %Gd-SnO2 and 2 %Gd-9 %F-SnO2 thin films for the photocatalytic degradation of MB by USP method(Inorganic Chemistry Communications, Elsevier Ltd, 2022-02-17) Sabrina Roguai 1; Abdelkader Djelloul 2In this study, SnO2, 2 %Gd-SnO2, and 2 %Gd-9 %F-SnO2 films were grown from tin chloride solutions by the ultrasonic spray technique on ordinary microscope glass substrates heated to a fixed temperature of 450 ◦C for photocatalytic application. The microstructural characterization of the thin films obtained was performed using X-ray diffraction (XRD), SEM, EDAX, and Infrared Spectroscopy (IR). The optical properties of thin films were studied by UV–Visible spectroscopy. To examine the electrical properties, we use the four-point method, the Seebeck effect and the Mott Shottky analysis. X-ray difraction reveals the formation of the routile phase of SnO2 in all thin films with average crystallite size estimated in the range of 24–62 nm. The co-doping in (Gd-F) permitted an improvement of the thermoelectric properties of SnO2. Moreover, we have demonstrated that an increase in grain size allows toimprove the Seebeck coefficient, to increase the electrical conductivity, on the other hand the doping in (Gd), presents a decrease in the size of the crystallites, which improves the degradation of methyl blue. The UV–Visible spectra of optical transmission of the layers show that the pure, doped and co doped SnO2 films are of good quality with a transmittance of 73–83% in the visible and have an optical gap evaluated between 3.89, 3.98 and 3.99 eV respectively.Item Gold coated vertically aligned carbon nanotubes as electrode for electrochemical capacitors(Thin Solid Films, Elsevier Ltd, 2023-05-20) Sabrina Roguai 1; Abdelkader Djelloul 2In this work, gold (Au) films were deposited onto vertically aligned carbon nanotubes (CNTs) by Dc magnetron sputtering method for use as super-capacitor electrodes. By so doing, we synthesize a porous Au deposit anchored on the CNTs with a high apparent surface area. The structure and microstructure studies revealed that the Au@CNTs have a porous nanostructure morphology. The porous Au/CNTs electrodes exhibit an a good areal capacitance compared to state of art Au based electrode (25.6 mF cm-2 at 5 mV.s-1) and excellent cycling stability (90% retention after 10.000 cycles) in 0.5 M H2SO4 aqueous solution. These results demonstrate the beneficial use of CNTs to fabricate a porous Au deposit with improved electrochemical energy storage. In addition, these porous structures can also be used as templates for another type of materials for electrochemical energy storage.Item Photocatalytic degradation of methylene blue using sprayed Mg diluted ZnO heterostructure thin flms photocatalysts(Reaction Kinetics, Mechanisms and Catalysis, 2021-03-07) Sabrina Roguai 1; Abdelkader Djelloul 2The thin layers of ZnOx%/MgO [x=30, 40 and 50 at%], were prepared by the spray pyrolysis method on glass substrates at 450 °C, then tested for methyl blue (MB) degradation under visible irradiations. The ZnOx%/MgO [x=30,40 and 50 at%] thin flms were analysed by X-ray difraction (XRD), scanning electron microscopy (SEM), UV–Vis spectroscopy and Mott-Schottky analysis. X-ray difraction analysis revealed that the layers have a polycrystalline nature of hexagonal (wurtzite) and cubic structure. Microstructures the flms were also analyzed using scanning elec tron. The flms show a radical change in the surface morphology in accordance with the XRD results. The above analyses confrm the co-existence of a mixture of the wurtzite (ZnO) structure and cubic phase of MgO. The use of these mixed layers in the photo degradation of MB gave satisfactory results. Indeed, the photocatalytic tests showed the efciency of Mg diluted ZnO flms with the best yield in the case of 50% diluted ZO flms. It was confrmed that the ZnO50%/MgO had a profound efect on reduction of band gap and photocatalytic performancesItem Roles of Cobalt Doping on Structural and Optical of ZnO Thin Films by Ultrasonic Spray Pyrolysis(. Licensee IntechOpen, Thin Films, 2021-05-10) Sabrina Roguai 1; Abdelkader Djelloul 2Here we report a systematic study of structural, optical, and magnetic measure ments of Zn1-xCoxO (x = 0–0.22 at.%) by Ultrasound pyrolysis spray technique. The hexagonal wurtzite structure of our films is confirmed by X-ray diffraction with an average crystallite size estimated in the range of 18–30 nm. For the optical proprie ties, using the Levenberg–Marquardt least squares rule, the experimental transmis sion measurements were perfectly adapted to the transmission data calculated by a combination of the Wemple-DiDomenico model, the absorption coefficient of an electronic transition and the Tauc-Urbach model. The concentration of the NCo absorption centers and the oscillator intensity f of the d-d transition of Co2+ ions are determined by the Smakula method. The presence of high concentrations of localized states in the thin films is responsible for the reduction in the width of optical bandgapItem Simulation of the Optical Properties of Zn1−xCoxO Thin Films Grown Onto Glass Substrate by Ultrasonic Spray Pyrolysis(International journal of science and research, 2023-07-14) Sabrina Roguai 1; Abdelkader Djelloul 2Zn1-xCoxO thin films (x=0-22 at.%) were prepared using the ultrasonic pyrolysis sputtering technique. The films have a hexagonal wurtzite structure, confirmed by X-ray difraction, with an estimated average crystallite size in the range of 18-30 nm. Concerning the optical properties, by applying the Levenberg-Marquardt least squares method, the experimental transmittance data were perfectly fitted with the transmittance data calculated via a combination of the Wemple-DiDomenico model, the absorption coefficient of an electronic transition and the Tauc-Urbach model. Decreases in bandgap energy due to the presence of high concentrations of localized states in thin films were calculated from the Smakula formulaItem Sn doping effects on the structural, microstructural, Seebeck coefficient, and photocatalytic properties of ZnO thin films(Solid State Communications, Elsevier Ltd, 2022-04-07) Sabrina Roguai 1 ,; Abdelkader Djelloul 2Successful ZnO, SnxZn1-xO [x = 0.01 and 0.03] films were synthesized by pyrolysis on glass substrates at Ts = 450 ◦C for 1 h. Sn doping effect on structural, microstructural, Seebeck coefficient and optical characterizations were performed. It found that all films crystallize in the hexagonal würtzite structure. The success of the 1 at.% Sn doping is confirmed by the SEM images which show that the microstructure of the 1 at.% Sn doped ZnO is rather similar to that of the undoped ZnO film and shows spherical grains, by further increasing the Sn content (3 at.%), the films show a small spherical grains. Through FTIR analysis, distinct characteristic absorption peak at 449 cm− 1 for the Zn–O stretching mode with some changes in intensities. ZnO, ZnO:Sn films transmit decrease from 87 to 66% with doping content, while the bandgap energy not affected with doping. The Seebeck coefficient decreases from |188| to |110|μV/K, while the carrier concentration increases from 3.37 × 1018 and 1.00 × 1019cm− 3 with doping content. The photocatalytic activity of Zn1-xSnxO investigated by testing the degradation of methylene blue (MB).Item Structural and optical analysis of SnO2 thin films BY Spray Pyrolysis(Algerian Journal of Environmental Science and Technology, www.aljest.org, 2022-03-16) Sabrina Roguai 1; Abdelkader Djelloul 2SnO2 thin films were deposited by ultrasound pyrolysis spray technique at 450°C. The films were characterized by X-ray diffraction, Fourier transformed infrared (FTIR), ultraviolet–visible and Photoluminescence spectroscopy. The tetragonal rutile-type structure was confirmed by X-ray diffraction with an average crystallite size of 35 nm. In addition, the FTIR study indicated the existence of two distinct characteristic absorptions which correspond to (0-Sn-O) deformations and (O-Sn) stretching modes. For the optical properties, the band gap energy was determined by Wemple DiDomenico model. PL properties are ascribed to the presence of intrinsic defects.Item Structural, microstructural and photocatalytic degradation of methylene blue of zinc oxide and Fe-doped ZnO nanoparticles prepared by simple coprecipitation method(Solid State Communications, Elsevier Ltd, 2021-05-04) Sabrina Roguai 1; Abdelkader Djelloul 2Nanoparticles of ZnO doped with Fe (0.00, 0.02, 0.05 and 0.10) were prepared by chemical co-precipitation method. The effect of iron doping on the structural, morphological and optical properties of ZnO nano particles was examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–Visible spectroscopy. The XRD analysis revealed the single-phase of the as made and Fe-doped ZnO nanoparticles. SEM images showed the formation of aggregates of small individual nanoparticles of various sizes. FTIR analysis indicated the existence of distinct characteristic absorption peaks at 447 cm− 1 for Zn–O stretching mode with some changes in the intensities. UV–Visible measurement revealed a reduction in the energy gap with increasing Fe concentration, which is generally due to increasing mesh pa rameters. The photocatalytic activity of Zn1-xFexO was evaluated by analyzing the degradation of methylene blue (MB). The presence of iron from 2% to 10 at% in the ZnO nanopowder was found to decelerate the photocatalytic process.Item Structural, microstructural and photocatalytic degradation of methylene blue of zinc oxide and Fe-doped ZnO nanoparticles prepared by simple coprecipitation method(Solid State Communications, Elsevier Ltd, 2021-05-04) Sabrina Roguai 1; Abdelkader Djelloul 2Nanoparticles of ZnO doped with Fe (0.00, 0.02, 0.05 and 0.10) were prepared by chemical co-precipitation method. The effect of iron doping on the structural, morphological and optical properties of ZnO nano particles was examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–Visible spectroscopy. The XRD analysis revealed the single-phase of the as made and Fe-doped ZnO nanoparticles. SEM images showed the formation of aggregates of small individual nanoparticles of various sizes. FTIR analysis indicated the existence of distinct characteristic absorption peaks at 447 cm− 1 for Zn–O stretching mode with some changes in the intensities. UV–Visible measurement revealed a reduction in the energy gap with increasing Fe concentration, which is generally due to increasing mesh pa rameters. The photocatalytic activity of Zn1-xFexO was evaluated by analyzing the degradation of methylene blue (MB). The presence of iron from 2% to 10 at% in the ZnO nanopowder was found to decelerate the photocatalytic process.Item Structural, microstructural, and optical properties of ZnO thin films prepared by spray pyrolysis(Algerian Journal of Renewable Energy and Sustainable Development, 2022-06-15) Sabrina Roguai 1; Abdelkader Djelloul 2The thin films of zinc oxide were deposited by the ultrasonic spray technique on glass substrates. Our interest consists in the study of structural and microstructural properties. The X-ray diffraction analysis of the samples shows that the thin films crystallize in the hexagonal structure of the Wurtzite type. With a preferential orientation along the c-axis perpendicular to the substrate surface. The average size of the crystallites of the order of 49 nm. The microstructures/nanostructures of thin films are characterized by the presence of nano pedals. The chemical composition of the films was analyzed by EDS which revealed the formation of the ZnO phase. The synthesized layers showed a transmittance value of 90%. The optical band gap and the refractive index values are in good accordance with available studies in the literature.Item Structural, morphological, optical and electrical properties of Ni-doped SnO2 thin films by pneumatic spray pyrolysis method(Bull. Mater. Sci, Indian Academy of Sciences, 2022-07-12) Sabrina Roguai 1; Abdelkader Djelloul 2In this study, we used a pneumatic spray pyrolysis technique at 450 C to deposit Sn1–xNixO2 thin films (0.0 B x B 0.10) on glass substrates. The influence of doping content on the films structural, morphological, optical and electrical properties was investigated. Structural characterization by X-ray diffraction indicated that the rutile phase of SnO2 is present in all thin films, and crystallite sizes are estimated to be in the range of 27–47 nm. Furthermore, structural and microstructural analyses revealed that at x = 0.05, there is a solubility limit for (Ni/Sn) in the SnO2 matrix. The optical bandgap energy increases from 3.83 to 4.01 eV as the dopant content increases according to the Burstein-Moss effect. Resistivity is affected by doping and the thickness of thin films. The figure-of-merit calculated for all samples showed significant differences in the Ni–SnO2 thin films. There was a difference between the doped thin films depending on the thickness. The lowest resistivity of 1.32 10-2 X cm and the maximum conductivity of 75 X-1 cm-1 was found at a Ni content of 2%. Seebeck coefficient of all the thin films developed had n-type conductivity, and the values of 76, 71, 133 and 69 l V/K for Ni-doped SnO2 thin films at 0, 2, 5 and 10 at.%, respectively, were found to improve the thermoelectric properties of SnO2 by Ni doping.Item Synthesis and evaluation of the structural, microstructural, optical and magnetic properties of Zn1−xCoxO thin flms grown onto glass substrate by ultrasonic spray pyrolysis(Applied Physics A, Springer-Verlag GmbH Germany, part of Springer Nature 2019, 2019-11-07) Sabrina Roguai 1; Abdelkader Djelloul 2Ultrasound pyrolysis spray technique is used to prepare single-phase thin flms of Zn1−xCoxO (x=0–22 at.%). The hexagonal wurtzite structure of the flms is confrmed by X-ray difraction with an average crystallite size estimated in the range of 18–30 nm. The compound structure and stoichiometry of the flms are further characterized by energy-dispersive spectros copy (EDAX). The spectrum analysis agreement great chords between the expected and measured Co atomic content in the flms indicating an efective doping. The results also reveal a high solubility of Co into ZnO solid solution at about 14 at.%. For the optical proprieties, the bandgap energy decreases due to the presence of high concentrations of localized states in the thin flms. The photoluminescence spectra of all the samples exhibited a broad emission in the visible range. In addition, the magnetic properties of Zn1−xCoxO thin flms are found to be strongly infuenced by Co doping.Item ZnO and La-doped ZnO films by USP method and their characterizations for ultraviolet photodetectors and photocatalysis applications(Inorganic Chemistry Communications, Elsevier Ltd, 2023-09-04) Sabrina Roguai 1; Abdelkader Djelloul 2In this study, ZnO, Zn1-xLaxO [2, 5, 10, 15 at.%] thin films were grown on glass substrates using the spray pyrolysis technique, to investigate the effect of doping on the structural, morphological, thermoelectric and optical properties of the layers, Also the samples were tested as UV photodetectors and photocatalyst for MB degradation. Firstly, diffraction patterns showed a hexagonal structure, with preferential grain orientation along the (002) direction, for pure ZnO and 2%La_ZnO layers, and at 5 at.% the preferential orientation changes, and crystallite sizes range from 10 nm to 19 nm. However, SEM images reveal that the ZnO and 2%La_ZnO layers are nanorods distributed over their surfaces, and the other 5%LZO, 10%LZO and 15%LZO layers characterized by nanocrystals were hexagonal prisms. The UV–visible analysis of the prepared layers shows high transparency (80–90%) in the visible range, with a constant optical gap of 3.26 eV. Thermoelectric measurements show that the ZnO and LZO layers are non-degenerate, with a maximum charge concentration of 9.18 × 1017 cm− 3 for the 15% LZO films. The thin films show an ability for UV detection, while the 5%La_ZnO layers remain the best for UV photodetection with a good sensitivity (5.07) compared with the other layers. In terms of methyl blue degradation, the 5%La_ZnO thin films had a better degradation of 95%.