Effect of annealing temperatures on the structural and optical properties of zinc oxide nanoparticles prepared by chemical precipitation method

In nature, leaf photosynthesis is the most common solar energy conversion system, which involves light absorption and conversion processes. Most interestingly, the leaves of a green plant are almos...

Solar-Heating Crassula perforata-Structured Superoleophilic CuO@CuS/PDMS Nanowire Arrays on Copper Foam for Fast Remediation of Viscous Crude Oil Spill.

Green synthesis of ZnO/carbon (ZnO/C) as an electrode material for symmetric supercapacitor devices

ZnO nano-rods were synthesised via wet chemical method at different nitrate concentration and pH value. The effect of pH and nitrate concentration on the size and morphology of the prepared ZnO photocatalysts have been investigated by particle size distribution analysis and Field emission scanning electron microscopy respectively. Additionally, UV-Visible spectroscopy and energy dispersive studies and were carried out to confirm the optical and compositional properties of the prepared ZnO powder. The estimated band gap of the as prepared ZnO photocatalysts at different pH and nitrate concentration calculated on the basis of Kubelka–Munk function was found to be in the range of ∼ 2.7–3.6 eV. Field emission scanning (FE-SEM) and transmission electron microscopic (TEM) observations reveal rod-like morphology. The photocatalytic activity of prepared ZnO photocatalysts was evaluated by photo degradation of the mixture of Methylene Blue (MB) and Rhodamine 6G (Rh 6G) solution under simulated solar radiation. Volume of hydrogen evolution was recorded in the presence of prepared ZnO photocatalysts in 2 h. Nitrate concentration, and pH value showed a significant effect on the optical and morphological behaviour of the prepared ZnO powdered photocatalysts.

The role of pH and nitrate concentration in the wet chemical growth of nano-rods shaped ZnO photocatalyst

In vitro evaluation of cytotoxicity, possible alteration of apoptotic regulatory proteins, and antibacterial activity of synthesized copper oxide nanoparticles.

Wet chemical synthesis of ZnO nanoflakes and photoluminescence

Morphological and optical property of spherical ZnO nanoparticles

Background: Metal oxide nanostructures are being investigated widely due to their strongoptical absorption, efficient photoluminescence, abundant of availability and structural stability whichlead them as a possible substitute of Si based solar cells and many optoelectronic and sensor devices.Due to their non-toxic nature they are supposed to be promising materials for drug delivery and medicalresearch. Among several metal oxides, cupric oxide (CuO) is being investigated nowadays due to their high transparencyand visible luminescence. It is a p-type semiconductor of band gap varying from 1.3 eV to 2.1 eV depending of thestructure and process of fabrication. This low band gap of CuO nanostructures leads its application in photoconductiveand photothermal applications. This leads rigorous investigations on CuO nanostructures.Methods: A simple wet chemical methods has been used to synthesize CuO bipods. Predetermined amount of Copper sulphatepenta-hydrate (CuSO4, 5H2O) was dissolved in double distilled de-ionized water to prepare 0.5 M solution. Predeterminedamount of Lithium hydroxide (LiOH) was dissolved in de-ionized water to prepare 1 M solution. Under rigorousmagnetic stirring of the LiOH solution CuSO4 solution was added drop by drop for five minutes and the stirring wasmaintained for 2 hours at room temperature (30°C). After the reaction a white precipitate was observed at the bottom ofthe flask. This solution was then aged for 24 hours. The color of the precipitate solution was turned into grey. The precipitatewas filtered and subsequently washed with distilled de-ionized water thrice for the removal of unreacted salts if any.The precipitate was then dried in an ordinary furnace at 150°C for further characterization.Results: X-ray diffraction data confirmed the formation of well crystalline CuO having monoclinic unit cell structure. Thecrystallite size was ~ 12 nm as calculated from the XRD pattern. Transmission electron microscope images revealed thatthe bipod-like structure is composed of several crystallites. The lengths of the bipods are ~ 300 nm with a waist size ~ 100nm. The UV-visible spectroscopic data revealed a strong absorption at ~ 376 nm and the band gap was calculated to be2.51 eV. FTIR spectrum revealed the existence of only Cu=O bonds. In the Raman shift data two strong peaks were foundat 273 cm-1, and 608 cm-1 that owe to the Ag mode and Bg mode respectively. Room temperature photoluminescencespectroscopy revealed that the CuO nanoparticles exhibit broad strong emission at ~ 472 nm. After decomposing we observedthree peaks at 436, 469 and 495 nm. The emission peak at 469 nm arises due to near band edge transition. Theemission peak at 495 nm arises due to shallow level defect states related transitions.Conclusion: In conclusion, we have fabricated CuO nano-bipods using a simple wet chemical method. XRD pattern indicatesthe formation of well crystalline and pure CuO without any impurity. The nano-bipods exhibit sharp absorption peakat ~ 376 nm with optical band gap energy of 2.51 eV. FTIR spectrum and Raman shift data confirms the formation ofCuO with the presence of Ag mode (273 cm-1) and Bg mode (608 cm-1). The fabricated CuO nano-bipods exhibit strongPL emission at 469 nm owing to the recombination of free excitons at the absorption band edge in the UV region associatedwith other low intense deep level emission. Few relevant patents to the topic have been reviewed and cited.

Abhijit Saha

Papers

Wet chemical synthesis of ZnO nanoflakes and photoluminescence

Morphological and optical property of spherical ZnO nanoparticles

Wet Chemically Synthesized CuO Bipods and their Optical Properties.