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The preparation of nanometer-sized structures of zinc oxide (ZnO) from zinc acetate and urea as raw materials was performed using conventional water bath heating and a microwave hydrothermal (MH) method in an aqueous solution. The oxide formation is controlled by decomposition of the added urea in the sealed autoclave. The influence of urea and the synthesis method on the final product formation are discussed. Broadband photoluminescence (PL) behavior in visible-range spectra was observed with a maximum peak centered in the green region which was attributed to different defects and the structural changes involved with ZnO crystals which were produced during the nucleation process.

Zn 1−x Mn x O nanostructures were synthesized via the microwave-assisted hydrothermal method, which rapidly produces particles of controlled size and morphology. Samples were analyzed considering the effects of manganese ion concentration. XRD revealed that all samples had wurtzite-type structure with Mn 2+ ions incorporated in the oxide lattice. UV−vis spectra showed absorption bands from the d−d transitions of Mn 2+ ions. As the doping concentration increased, the value of the energy gap decreased, indicating intermediary energy levels within the band gap in the Mn-doped ZnO samples. All samples produced broadband photoluminescence (PL) emissions in the yellow−orange− red range. Additionally, the PL intensity decreased with Mn 2+ ion incorporation into the ZnO lattice due to the creation of new recombination centers. Microscopy images showed that manganese in the ZnO matrix produced homogeneously distributed nanostructures. EPR results indicated two locations of Mn 2+ ions in the ZnO lattice, lower concentrations in the core of the lattice and higher concentrations at the surface.

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Rapid synthesis of CO, NI CO-doped ZnO nanoparticles: Optical and electrochemical properties, Journal of Solid State Chemistry, http://dx. AbstractWe report for the first time a rapid preparation of Zn 1-2x Co x Ni x O nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green-orange-red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra.Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni codoped ZnO samples when compared to pure ZnO.

Objectives This study aimed to synthesize nanocrystals (NCs) of zinc oxide (ZnO) and calcium ion (Ca 2+ )-doped ZnO with different percentages of calcium oxide (CaO), to evaluate cytotoxicity and to assess the effects of the most promising NCs on cytotoxicity depending on lipopolysaccharide (LPS) stimulation. Materials and Methods Nanomaterials were synthesized (ZnO and ZnO:xCa, x = 0.7; 1.0; 5.0; 9.0) and characterized using X-ray diffractometry, scanning electron microscopy, and methylene blue degradation. SAOS-2 and RAW 264.7 were treated with NCs, and evaluated for viability using the MTT assay. NCs with lower cytotoxicity were maintained in contact with LPS-stimulated (+LPS) and nonstimulated (−LPS) human dental pulp cells (hDPCs). Cell viability, nitric oxide (NO), and reactive oxygen species (ROS) production were evaluated. Cells kept in culture medium or LPS served as negative and positive controls, respectively. One-way analysis of variance and the Dunnett test (α = 0.05) were used for statistical testing. Results ZnO:0.7Ca and ZnO:1.0Ca at 10 µg/mL were not cytotoxic to SAOS-2 and RAW 264.7. +LPS and −LPS hDPCs treated with ZnO, ZnO:0.7Ca, and ZnO:1.0Ca presented similar NO production to negative control ( p > 0.05) and lower production compared to positive control ( p < 0.05). All NCs showed reduced ROS production compared with the positive control group both in +LPS and −LPS cells ( p < 0.05). Conclusions NCs were successfully synthesized. ZnO, ZnO:0.7Ca and ZnO:1.0Ca presented the highest percentages of cell viability, decreased ROS and NO production in +LPS cells, and maintenance of NO production at basal levels.

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We describe the preparation of bismutite ((BiO) 2 CO 3 ) and bismuth-oxide (Bi 2 O 3 ) plates-like nanostructures and their incorporation within graphite-composite electrodes for the determination of trace metals by anodic-strippingvoltammetry. The bismuth nanostructures were produced under microwave-hydrothermal conditions followed by thermal conversion of as-prepared precursor and characterized by X-ray diffraction, Fourier-transformed infrared and field-emission scanning-electron-microscopy. Graphite-composite electrodes bulk-modified with Bi 2 O 3 nanostructures provided higher sensitivity and lower detection limits for determinations of cadmium, lead and zinc (0.26; 0.52; and 2.23 mg L À1, respectively) employing short deposition time (60 s). The results indicate that the modification of graphite-composite electrodes with Bi 2 O 3 nanostructures improved analytical characteristics of electrochemical sensors for trace-metal determinations.