Mohammad Ramzan Parra

PVP Assisted Shape-Controlled Synthesis of Self-Assembled 1D ZnO and 3D CuO Nanostructures

Self-assembled one-dimensional (1D) zinc oxide (ZnO) rods and three-dimensional (3D) cupric oxide (CuO) cubes like nanostructures with a mean crystallite size of approximately 33 and 32 nm were synthesized through chemical route in the presence of polyvinylpyrrolidone (PVP) under mild synthesis conditions. The technique used for the synthesis of nanoparticles seems to be an efficient, inexpensive and easy method. X-Ray diffraction patterns confirmed well crystallinity and phase purity of the as prepared samples, followed by the compositional investigation using Fourier Transform Infrared (FT-IR) spectroscopy. The formation of ZnO nanorods and CuO nanocubes like structures were through Scanning Electron Microscopy (SEM) images. The mechanism and the formation factors of the self-assembly were discussed in detail. It was clearly observed from results that the concentration of precursors and PVP were important factors in the synthesis of self-assembly ZnO and CuO nanostructures. These self-assembly nanostructures maybe used as novel materials in various potential applications.

Optical study and ruthenizer (II) N3 dye-sensitized solar cell application of ZnO nanorod-arrays synthesized by combine two-step process

Highly dense ZnO nanorod-arrays were successfully synthesized with uniform c-axis growth by using combine two-step process: sol-gel spin coating followed by the aqueous solution growth method. Structural and optical properties of ZnO nanorod-arrays were investigated. The X-ray diffraction results revealed that ZnO nanorod arrays exhibit wurtzite hexagonal crystal structure with a dominant (002) peak with high crystallinity. Nanorods of 3–4 μm length and 500 nm diameter, with surface roughness ∼20 nm were observed. Furthermore, Raman spectroscopic results revealed the presence of E2 peak ∼438 cm–1 which again corroborated the existence of wurtzite crystal structures assigned to ZnO. The optical transmittance spectrum indicated that the transmittance of more than 80% was observed in the visible and infrared (IR) regions with the optical band-gap energy ∼3.35 eV. Photoluminescence spectrum showed peaks in ultra-violet (382.0 nm) and green region (524.9 nm), which specified good-quality crystallite formation containing high density of surface defects, zinc interstitials and oxygen-vacancies. Ruthenizer (II) N3-dye loaded sensitized solar cell test illustrated that the uniform ZnO nanorod-arrays as working electrode with a short circuit current density of 3.99 mA/cm2, fill factor ∼50% and overall power conversion efficiency (η) ∼1.36% might be a promising electrode material of dye sensitized solar cell application.

Optimization of process parameters and its effect on structure and morphology of CuO nanoparticle synthesized via the sol−gel technique

AbstractThis article describes systematic basic research on the optimization of the processing parameters of sol−gel technique for synthesis of the high purity CuO nanoparticles. Effect of the synthesis parameters such as copper salt concentration, solvent and gelating agent, optimized one at a time, was investigated by employing XRD, TEM, FESEM, micro-Raman, UV-visible-NIR and PL spectroscopies. XRD results clearly demonstrate the monoclinic structure of CuO nanoparticles with traceable impurities at a lower molar concentration of Cu2+, transition of nucleation system from homogeneous to heterogeneous state with the increase in concentration of Cu2+ from 0.05 to 0.15 M. It was also found that the isopropyl alcohol offers better results in comparison to ethanol and water. Moreover, the lattice parameters, space group, and crystal system were determined by powder X-ray diffraction method. Further we propose the optimization of synthesis process using ethylene glycol and citric acid (EG:CA). The Raman analysis confirmed the influence of ethylene glycol and citric acid ratio and TEM observations confirmed that EG:CA 1:2 ratio formulate homogenous flower-like nanostructures. The optical absorption of CuO nanostructures can be easily tuned by varying the concentration of citric acid without changing other conditions; it shows the role of synthesis parameters more significant. Our results suggest that the prepared CuO nanostructures have a potential to be used as absorbing material in solar cell applications. HighlightsCuO nanoparticles are successfully synthesized via simple non-aqueous sol-gel method.The effect of various process parameters on the morphology and structure of CuO nanoparticles are investigated.Vibrant modifications in the morphology of CuO nanoparticles are detected via TEM and SEM.Isopropyl alcohol gives better crystallization of CuO nanostructures in comparison to ethanol.1:2 ratio of ethylene glycol and citric acid yield superior assembly of CuO nanostructures.

Structural and Optical Characterization of ZnO Nanoparticles Synthesized Via Low Temperature Precipitation Method

ZnO nanoparticles were successfully synthesized via a low temperature and simple precipitation method. Crystallinity, phase purity and structural properties of as prepared material were analyzed by X-ray diffraction pattern (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) with 32 nm average crystallite size. Additionally, the optical properties of the sample were investigated by using Uv-Vis-NIR and Photoluminescence spectroscopy with an energy band gap at 3.09 eV. These results should be useful in developing optoelectronic devices such as UV-LEDs and laser diodes.

Synthesis and Optical Properties of Pure and Eu+3 Ion Doped ZnO Nanoparticles Prepared Via Sol-Gel Method

Eu-doped Zinc Oxide nanoparticles, with wurtzite hexagonal phase have been successfully synthesized via simple sol-gel method. Crystallinity, morphologies and optical properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), Atomic Force microscopy (AFM) and photoluminescence spectroscopy (PL). XRD results indicated that trivalent europium ions were successfully doped into the crystal lattice of ZnO matrix with ~13 nm average crystallite size. X-ray peak broadening analysis was used to evaluate the average crystallite size and lattice strain by the Williamson-Hall (W-H) method. Photoluminescence spectroscopic results indicated that the emission peak located at ~610 nm was attributed to the 4f–4f intra-shell transition of 5D0 → 7F2 incorporated into wurtzite ZnO host by substitution on the Zn sub lattice.