Influence of Reaction Time, Reducing Agent and Zinc Precursors on the Morphological Structures of Zinc Oxide

ZnO either nanoparticles or nanorods were synthesized via sol-gel technique. Many factors were studied and optimized in order to obtain different morphological structures of nano-ZnO. Effect of reaction time (3, 6, 12, 24 and 48 hours) has been studied to optimize the best preparation condition. Reducing agent (NH3, NaOH and KOH) is one of the factors affect on morphological structures, which has been studied in this work. Other effect has been studied in this work is zinc precursors such as Zn(NO3)2, ZnAc2, ZnCl2, and ZnBr2. The morphological structures of prepared ZnO were revealed using scanning electron microscope (SEM) and the aspect ratios were calculated. x-ray diffraction (XRD) patternsexposed a highly crystallized wurtzite structure and used for identifying phase structure and chemical state of ZnO under different preparation conditions.Keywords: sol-gel, morphological structures, reducing agent, SEM, preparation conditions

Fabrication of ZnO and ZnO:Sb Nanoparticles for Gas Sensor Applications

ZnO and Sb-doped ZnO nanoparticles were successfully prepared using sol-gel technique. Different concentrations of triethanolamine (TEA) were utilized as the preparation procedure to act as complexing agent that enhances the doping probability of the formed Sb-doped ZnO nanopowder. Thick films of the prepared nanopowders were fabricated with spinner coating. Morphological characteristics, phase structure, chemical composition, thermal stability, and optical properties of the prepared nanopowders were measured and analyzed. The average crystallite size of ZnO and ZnO:Sb powders ranged between 19–28 nm according to the XRD calculations and TEM observations. The gas sensitivity of the homemade devices based on Sb-doped ZnO nanoparticles towards O2 and CO2 gases as a function of temperature was measured and compared with undoped ZnO films. The gas sensitivity of the films was greatly improved after doping with Sb and reached its maximum value of ~86% for O2 gas at 93:7 wt% of Zn:Sb

Influence of Reaction Time, Reducing Agent and Zinc Precursors on the Morphological Structures of Zinc Oxide

ZnO either nanoparticles or nanorods were synthesized via sol-gel technique. Many factors were studied and optimized in order to obtain different morphological structures of nano-ZnO. Effect of reaction time (3, 6, 12, 24 and 48 hours) has been studied to optimize the best preparation condition. Reducing agent (NH3, NaOH and KOH) is one of the factors affect on morphological structures, which has been studied in this work. Other effect has been studied in this work is zinc precursors such as Zn (NO3)2, ZnAc2, ZnCl2, and ZnBr2. The morphological structures of prepared ZnO were revealed using scanning electron microscope (SEM) and the aspect ratios were calculated. x-ray diffraction (XRD) patterns exposed a highly crystallized wurtzite structure and used for identifying phase structure and chemical state of ZnO under different preparation conditions

CdSe Quantum Dots for Solar Cell Devices

CdSe quantum dots have been prepared with different sizes and exploited as inorganic dye to sensitize a wide bandgap TiO2 thin films for QDs solar cells. The synthesis is based on the pyrolysis of organometallic reagents by injection into a hot coordinating solvent. This provides temporally discrete nucleation and permits controlled growth of macroscopic quantities of nanocrystallites. XRD, HRTEM, UV-visible, and PL were used to characterize the synthesized quantum dots. The results showed CdSe quantum dots with sizes ranging from 3 nm to 6 nm which enabled the control of the optical properties and consequently the solar cell performance. Solar cell of 0.08% performance under solar irradiation with a light intensity of 100 mW/cm2 has been obtained. CdSe/TiO2 solar cells without and with using mercaptopropionic acid (MPA) as a linker between CdSe and TiO2 particles despite a Voc of 428 mV, Jsc of 0.184 mAcm-2, FF of 0.57, and η of 0.05% but with linker despite a Voc of 543 mV, Jsc of 0.318 mAcm-2 , FF of 0.48, and η of 0.08%, respectively

Development of High-Performance Supercapacitor based on a Novel Controllable Green Synthesis for 3D Nitrogen Doped Graphene

Abstract 3D sponge nitrogen doped graphene (NG) was prepared economically from waste polyethylene-terephthalate (PET) bottles mixed with urea at different temperatures using green approach via a novel one-step method. The effect of temperature and the amount of urea on the formation of NG was investigated. Cyclic voltammetry and impedance spectroscopy measurements, revealed that nitrogen fixation, which affects the structure and morphology of prepared materials improve the charge propagation and ion diffusion. The prepared materials show outstanding performance as a supercapacitor electrode material, with the specific capacitance going up to 405 F g−1 at 1 A g−1. An energy density of 68.1 W h kg−1 and a high maximum power density of 558.5 W kg−1 in 6 M KOH electrolytes were recorded for the optimum sample. The NG samples showed an appropriate cyclic stability with capacitance retention of 87.7% after 5000 cycles at 4 A g−1 with high charge/discharge duration. Thus, the prepared NG herein is considered to be promising, cheap material used in energy storage applications and the method used is cost-effective and environmentally friendly method for mass production of NG in addition to opening up opportunities to process waste materials for a wide range of applications

Synthesis, characterization and evaluation of new alternative ruthenium complex for dye sensitized solar cells

Abstract For first time, new innovative ruthenium N3-Dye anchored with selenium (Se) and N3 dye anchored with sulphur atoms were synthesized in a good yield. Dyes are applied and evaluated in performance of dye sensitized solar cell. N3–Se dye showed superior photochemical& electrochemical behavior and high rate electron transfer across anode surface than N3–S dye. The better optical and electrochemical activities would make Se-dye a candidate for applications in solar cells. Half life time of N3–S showed a single exponential decay with an average lifetime of 0.8 ns. For N3–Se dye, decay curve was fitted by sum two exponential functions with 75% and 25% counts have 2.5 ns and 30 ns respectively. Solar cells were fabricated and analyzed to determine their solar-to-electric conversion efficiency under standard AM 1.5 sunlight. Commercial N3 dyes showed current density (Jsc) of 17.813 mA cm−2, open circuit potential (Voc) of 0.678 V, filling factor (FF) of 0.607 and conversion efficiencies (η) of 7.3%. Corresponding values for N3–S dye, Jsc 11.2 mA cm−2, Voc 0.650 V, FF 0.681 and η 5%. Se–N3 dye, showed Jsc = 6.670 mA cm−2, Voc = 0.6004 V, FF = 0.77 and η = 3.09%. Long lifetime of N3–Se caused low practical performance

Synthesis of Nanostructure In_xGa_1−xN Bulk Alloys and Thin Films for LED Devices

In this study, we investigated an innovative method for the fabrication of nanostructure bulk alloys and thin films of indium gallium nitride (InxGa1−xN) as active, thin films for light-emitting diode (LED) devices using both crystal growth and thermal vacuum evaporation techniques, respectively. These methods resulted in some tangible improvements upon the usual techniques of InxGa1−xN systems. A cheap glass substrate was used for the fabrication of the LED devices instead of sapphire. Indium (In) and Gallium (Ga) metals, and ammonia (NH3) were the precursors for the alloy formation. The alloys were prepared at different growth temperatures with compositions ranging from 0.1 ≤ x ≤ 0.9. InxGa1−xN alloys at 0.1 ≤ x ≤ 0.9 had different crystallinities with respect to X-Ray diffraction (XRD) patterns where the energy bandgap that was measured by photoluminescence (PL) fell in the range between 1.3 and 2.5 eV. The bulk alloys were utilized to deposit the thin films onto the glass substrate using thermal vacuum evaporation (TVE). The XRD thin films that were prepared by TVE showed high crystallinity of cubic and hexagonal structures with high homogeneity. Using TVE, the InxGa1−xN phase separation of 0.1 ≤ x ≤ 0.9 was eliminated and highly detected by XRD and FESEM. Also, the Raman spectroscopy confirmed the structure that was detected by XRD. The FESEM showed a variance in the grain size of both alloys and thin films. The InxGa1−xN LED device with the structure of glass/GaN/n-In0.1Ga0.9N:n/In0.1Ga0.9N/p-In0.1Ga0.9N:Mg was checked by the light emitted by electroluminescence (EL). White light generation is a promising new direction for the fabrication of such devices based on InxGa1−xN LED devices with simple and low-cost techniques

Comprehensive study of nanostructured Bi2Te3 thermoelectric materials - insights from synchrotron radiation XRD, XAFS, and XRF techniques

In this contribution, a comprehensive study of nanostructured Bi2Te3 (BT) thermoelectric material was performed using a combination of synchrotron radiation-based techniques such as XAFS, and XRF, along with some other laboratory techniques such as XRD, XPS, FESEM, and HRTEM. This study aims to track the change in morphological, compositional, average and local/electronic structures of Bi2Te3 of two different phases; nanostructure (thin film) and nanopowders (NPs). Bi2Te3 nanomaterial was fabricated as pellets using zone melting process in a one step process, while Bi2Te3 thin film was deposited on sodalime glass substrate using a vacuum thermal evaporation technique. Synchrotron radiation-based Bi LIII-edge fluorescence-mode X-ray absorption fine structure (XAFS) technique was performed to probe locally the electronic and fine structures of BT thin film around the Bi atom, while transmission-mode XAFS was used for BT NPs distributed in the PVP matrix. The structural features of the collected Bi LIII XANES spectra of thin film and powder samples of BT are compared with the simulated XANES spectrum of BT calculated using FDMNES code at 5 Å cluster size. Combining different off-line structural characterization techniques (XRD, FESEM, XPS, and HRTEM), along with those of synchrotron radiation-based techniques (XAFS and XRF) is necessary for complementary and supported average crystal, chemical, morphological and local electronic structural analyses for unveiling the variation between Bi2Te3 in the nanostructure/thin film and nanopowder morphology, and then connecting between the structural features and functions of BT in two different morphologies. After that, we measured the Seebeck coefficient and the power factor values for both the BT nanopowder and thin film