Effect of Citric Acid Addition upon the Precipitation Process on the Nanostructural Characteristics of ZnO Nanoparticles (original) (raw)
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2018
ZnO nanoparticles (ZnO NPs) were synthesized using hydrothermal and sol-gel techniques using zinc acetate dihydrate (Zn (CH3COO)2.2H2O) as a row material and methanol as a solvent. The structural properties of ZnO NPs were studied using EDX, XRD, TEM, and the optical properties were characterized using UV-VIS and PL spectroscopies. The synthesized ZnO NPs showed high purity and revealed a wurtzite (hexagonal) crystal structure with particle size (D) ranged from 25 nm to 28 nm. The UV-VIS absorption spectra of ZnO NPs samples and sensitizing dyes were performed. The obtained ZnO NPs exhibited the direct optical bandgap 3.15 eV. Dye-sensitized solar cells (DSSCs) were fabricated using synthesized ZnO NPs as a semiconducting layer, which was dyed with different low cost dyes such as Eosin B (EB), Eosin Y (EY) and Rhodamine B (RB) that was used to sensitize the photoanode (ZnO NPs). The experimental results showed a significant efficiency for the fabricated DSSCs of synthesized ZnO NPs ...
Electrochimica Acta, 2008
In this work, the morphology of ZnO materials could be controlled by changing the capping agent at constant alkali solution in hydrothermal process. ZnO nanomaterials with the structure of flowers, sheet-spheres and plates were obtained with the capping agent of ammonia, citric acid and oxalic acid, respectively. Thus prepared ZnO nanomaterials were characterized and applied as the photo-anode materials for dye-sensitized solar cell. All synthesized ZnO nanomaterials possessed high crystalline wurtzite structures grown in the (0 0 1) direction with the size of 2-4 m, which consist of ZnO units around 20-400 nm. Among them, Sheet-sphere ZnO showed the highest crystallinity, surface area and uniform film morphology, resulting in the significantly improved PV performance with the overall conversion efficiency of 2.61% in dye-sensitized solar cell (DSSC) fabricated with sheet-sphere ZnO. It is notable that the ZnO materials with sphere structure may be the optimal photo-anode material among various ZnO nanomaterials for DSSC.
Journal of Institute of Science and Technology, 2019
X-ray diffraction, Raman investigations, band gap energy of zinc oxide nanoparticles (ZnO NPs) along with current-voltage characteristic curves of an assembled dye-sensitized solar cell (DSSC) are presented in this article. ZnO NPs were first synthesized with and without potassium nitrate (KNO3) salt by precipitation method from precursor solutions of zinc acetate and sodium hydroxide. Then, their thin films were deposited on FTO substrates from the paste made with acetic-acid glacial, and Triton X-100 in ethanol by doctor blade method. The X-ray diffraction (XRD) pattern of ZnO NPs prepared without KNO3 annealed at 500°C showed a hexagonal wurtzite structure with preferred orientation along (101) planes and crystallite size of 25 nm. Very similar XRD pattern was found for ZnO NPs prepared with KNO3. The crystallite size was found decreased to 17 nm for ZnO NPs made with KNO3 salt. Raman spectrum of ZnO NPs showed the presence of E2 high or E2 (2) peak at 437 cm-1. The optical band...
Journal of Materials Science: Materials in Electronics, 2014
Zinc oxide thin films have been successfully prepared by co-precipitation and electrodeposition methods onto Fluorinated tin oxide substrate using zinc nitrate aqueous solutions at various bath temperatures (25-75°C). The deposition of electrodeposition method was conducted using both using linear sweep voltammetry and Chronoamperometric techniques. The effects of solution composition, agitation and bath temperature on the electrochemical measurements and ZnO film characteristics were fully analyzed. The findings reveal that temperature and nitrate ion concentration have a strong promoting effect on ZnO film formation. Moreover, the obtained powders were investigated by X-ray diffraction, Field emission scanning electron microscopy and UV-Vis Spectroscopy. Structural characterization by X-ray diffraction indicates the formation of ZnO phase and the deposited film exhibits the Zincite structure with crystallite size around 51 nm. The photovoltaic performance of dye-sensitized solar cells based on both ZnO prepared by co-precipitation and electrodeposition methods was investigated. A power conversion efficiency (g) of 3.5 % was achieved for the DSSC with co-precipitation ZnO, which is higher than that of the cell with electrodeposition ZnO (2.5 %). Explanations are substantiated by incident photon to electron conversion efficiency curves.
Synthesis of nanocrystalline ZnO powder via sol–gel route for dye-sensitized solar cells
2008
This paper reports the growth mechanism of sol–gel-derived nanocrystalline ZnO powder. The influence of pH value of the sol on the crystallite size, morphology and structure of ZnO powder was investigated by using X-ray diffraction, transmission and scanning electron microscopy. Maximum size nanocrystallite (∼14 nm) of ZnO powder was obtained for pH value of 9. An increase in the band gap (blue shift) was observed with decrease in the size of the ZnO nanocrystallites. The variation in band gap was found to be in agreement with theoretical calculations using effective mass model. The growth mechanism of ZnO particles from zinc acetate dihydrate precursor by the sol–gel process has been discussed in terms of solvation, hydrolysis and polymerization. The synthesized ZnO powders were successfully used as the electrode material for dye-sensitized solar cells.
Key Engineering Materials, 2018
In the current study, various morphologies of zinc oxide (ZnO) including nanorods, nanoflowers, nanosheets/flakes, nanospherical particles, nanohexagonal sheets, and nanoneedles have been prepared by using single step and two-step hydrothermal processes with optimized parameters such as growth temperature, growth time and compositions of both the seed and growth solutions. Fluorine doped tin oxide (FTO) coated glass was used as the substrate. The prepared morphologies were characterized with the help of scanning electron microscopy (SEM) and the purity of nanostructures was confirmed by elemental analysis (EDX). These nanostructures were used as photo-anode material to fabricate the DSSC using a dye (Rhodamine B) for enhancing the range of solar spectrum that is to be adsorbed. Finally the fabricated solar cells were characterized in terms of their efficiency, gauged by their fill factor. Among different morphologies investigated as photo anode materials; nanosheets/flakes were foun...
Synthesis and Characterization of ZnO Nanoparticles
ZnO nanoparticles with particle size less than 50nm are synthesized by simple sol gel method. These nanoparticles can be used as a source layer for the extraction of electrons in heterojunction organic solar cells. Zinc acetate is used as a precursor material in this case. X-Ray powder Diffraction, Ellipsometery and Scanning Electron Microscopy are used to study the crystal structure, optical properties and surface morphology of the synthesized nanoparticles, respectively. The presence of (100), (002) and (101) planes in the XRD graphs strongly indicates that ZnO has wurtzite structure even under as-synthesized conditions. Surface morphology was studied by SEM which indicates that the nanoparticles are of spherical shape with size less than 100 nm. Large area growth of these nanoparticles is also observed with uniform size distribution. A remarkable decrease in the transmission values is observed by increasing the pH from 2 to 9. Refractive index ~ 1.5 is observed at 350nm for all of the samples except the one synthesized with pH 9.
Synthesis and characterization of Zinc Oxide nanoparticles for Dye Sensitized Solar Cells
Zinc is a transition metal of group XII. It is hexagonal in structure. Zinc oxide is classified as a semiconductor in group II-VI of the periodic table. Zinc oxide exits in two structures namely Wurzite and Cubic Zincblende. The hexagonal Wurtzite structure is most stable at ambient conditions and is most common. Zinc oxide crystalline Nanoparticles were synthesized using chemical route method. TEM was used to study the morphology and growth structure of Zinc oxide. PL and UV studies were used for understanding the optical properties of Zinc oxide Nanoparticles. The particle size ranges from 146 nm to 148 nm. The PL spectra was found to exhibit emission at 469 nm and excitation spectra was recorded at 490 nm.
Synthesis and microstructural properties of ZnO nanoparticles prepared by precipitation method
Renewable Energy, 2013
In this work, zinc oxide (ZnO) precursor was prepared by precipitation method from zinc nitrate and ammonium carbonate in aqueous solutions. ZnO nanoparticles were synthesized by annealing the precursor at different temperatures. The effect of the annealing temperature on the particle size and photo-luminescence (PL) properties of the synthesized ZnO nanoparticles were studied by XRD, SEM, BET, TG-DTA and PL measurements. The XRD results indicated that the synthesized ZnO nanoparticles had the pure wurtzite structure. It is found that with increasing the annealing temperature the crystalinity and particle size increases as well as the lattice parameters approaches to those of the XRD standard. The studies of the aggregation of the samples were also carried out by comparing SEM micrographs with specific surface measurements and XRD results. Finally, the room temperature PL spectra show UV emission peak in the range of 378.50e379.80 nm, which is close to the bulk ZnO.
An Empirical Study on Structural, Optical and Electronic Properties of ZnO Nanoparticles
In this work, the synthesis routes for zinc oxide (ZnO) nanoparticles and optical & electronic properties of ZnO nanoparticles have been demonstrated. ZnO has many potential applications including sunscreens, biosensors, food additives, pigments, rubber manufacture, and electronic materials. Because of the unique quantum confinement effects of ZnO nanoparticles, synthesis and characterization of ZnO nanoparticles has been received a great attention in contemporary materials science. The synthesized ZnO materials can be further characterized by many characterization techniques in order to confirm synthesis. In this case, X-ray diffraction (XRD is a very powerful tool to analyse the structure of the material. Surface characterization such as Scanning Electron Microscopy (SEM) and Transmission electron microscopy (TEM)could be very useful to understand the morphology of the nanoparticles. Also, Fourier transform infrared spectroscopy (FTIR) is helpful to identify particular chemical bonding in the synthesized materials. Thermal stability and thermal transition can be measured by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. The optical properties of ZnO nanoparticles can be measured by UV-VIS spectroscopy.