A practical and economical method was developed for the production of an antibacterial cotton fabric using zinc oxide nanostructures without the use of surface modifying agents. In this process, zinc nitrate hexahydrate and potassium hydroxide were used as starting materials and the reaction was performed at 50°C. The in situ growth of ZnO nanostructures on cotton fabric occurred in a single-stage process, and it started when the fabric samples were dipped for 1 min in the solution containing all the starting materials. The treated and untreated fabric samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and EDS. The cotton fabrics coated with ZnO nanostructures presented an antibacterial efficiency towards Pseudomonas aeruginosa, a gram-negative bacteria, and Staphylococcus aureus (S. aureus), a gram-positive bacteria.

The semiconductor zinc oxide (ZnO) has been widely used because it presents exclusive novel physical and chemical properties at the nanometer scale. In this work, ZnO nanocrystals were synthesized via solochemical processing in a few hours without any subsequent treatment. ZnCl2 and NaOH were adopted as synthesis precursors. ZnO production was realized at different reaction temperatures to verify the effect of this parameter on synthesis. The synthesis temperatures studied were 50 degrees C, 70 degrees C and 90 degrees C. The materials obtained at different reaction temperatures were characterized by X-ray diffraction (XRD) and the Rietveld method. The size and morphology of the ZnO particles obtained at 50 degrees C were evaluated by transmission electron microscopy (TEM). ZnO powders have hexagonal wurtzite structure and nanometric-sized crystallites. Microstrain increased and the average crystallite size decreased with the increase in reaction temperature.

ZnO nanocrystals were successfully prepared under mild conditions by solochemical method from sodium hydroxide and zinc nitrate hexahydrate in 3 h refluxing. In this process the dependence of the morphologies, sizes and formation mechanisms of the ZnO nanocrystals on the reaction temperature was investigated. The samples were analyzed by X-ray diffraction (XRD), including Rietveld analyses, transmission electron microscopy (TEM), Raman spectroscopy and UV-Visible absorption spectroscopy. The X-ray diffraction patterns revealed that the formed products are pure ZnO with hexagonal (wurtzite) structure. Rietveld analyses of the XRD patterns showed anisotropic effects on the size and microstrain of ZnO nanocrystals. The anisotropy on the crystallite size decreases as the reaction temperature increases. The microstrain remains constant up to 90 degrees C when reached highest values in all directions. The transmission electron microscopy images showed short ZnO nanorods and rounded shape nanoparticles for all samples. The average size (length by diameter) ratio of the ZnO nanorod increased from 1.5 to 2.4 when reaction temperature was raised from 50 degrees C to 80 degrees C and decreased to 1.4 as the temperature was further increased to 90 degrees C. The HRTEM image of the sample prepared at 90 degrees C showed that ZnO nanocrystals have their c-axes as the primary growth direction. The wurtzite structure in ZnO nanorods has been verified by its characteristic E2 mode in the Raman spectra of all samples. All Raman peaks (especially for E2 mode) observed for the sample prepared at 90 degrees C showed huge intensity reduction and linebroadening, except for the second order Raman mode at about 1068 cm(-1) which presented a very huge and unusual increase on intensity. All samples presented a blue shift in the excitonic absorption compared to ZnO bulk that increases alongside with reaction temperature. In addition a mechanism for the synthesis of ZnO nanocrystals using zinc nitrate hexahydrate and sodium hydroxide by the solochemical method has also been proposed.

This work evaluates the effect of ZnCl 2 and Zn(NO 3 ) 2 .6H 2 O as precursors in the synthesis of ZnO nanocrystals. The materials were obtained at 90 °C by a simple solochemical route. The resulting samples were characterized regarding phase composition, particle size and morphology, by means of XRD and TEM. The analysis have provided evidences that the material obtained applying Zn(NO 3 ) 2 .6H 2 O as precursor has hexagonal crystalline structure, typical of the ZnO, and dimensions in the nanoscale. However, applying ZnCl 2 as precursor results in a mixture of ZnO and Zn 5 (OH) 8 Cl 2 .H 2 O phases. For both precursors, the predominant morphology of the obtained ZnO nanocrystals was the rod-like structure.

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Substantial efforts have been devoted towards researching routes that provide an appropriate and simple approach for the production of zinc oxide (ZnO) nanocrystals. Here, a rapid and inexpensive solochemical method was employed to synthesize ZnQ nanocrystals through the decomposition of zinc chloride (ZnCl2) and sodium hydroxide (NaOH) at 50 degrees C, 70 degrees C and 90 degrees C. The powders were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The products showed high purity, nearly uniform rod-like morphology and nanometric crystallite sizes. With increasing reaction temperature, the crystallites become smaller and rounded. The Raman results reveal correlations between Raman line widths and intensities with ZnO nanorods dimensions. More specifically, the line widths are large and therefore less intense as the nanorod becomes smaller.

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