Nanostructured luminescent ZnO and SnO 2 materials are prepared by a solidstate method based on the pyrolysis of hybrid macromolecular precursors ZnCl 2 •Chitosan and SnCl 2 •Chitosan having different [polymer/MCl 2 ] (M = Zn or Sn) ratios (1:1, 1:5 and 1:10), under air at 800°C .The pyrolytic ZnO and SnO 2 nanomaterials show a dependence of the particle size, morphology and luminescent properties with the ratio [metal/polymer] in the MCl 2 •Chitosan precursors. Thus, ZnO semiconductor materials exhibit luminescence spectra with several emission peaks between 300 and 600 nm. The most intense emission at 440 nm corresponds to a radiative transition of an electron from the shallow donor level of oxygen vacancies, and the zinc interstitial, to the valence band. All the ZnO materials synthesized show a rather intense green emission at ca. 573 nm, which is characteristic of this synthetic methodology. On the other hand, the photoluminescence spectrum of the nanostructured SnO 2 shows an intense blue luminescence at a wavelength of 420 nm which may be attributed to oxygen-related defects that have been introduced during the growth process of the nanoparticles. In other hand, whereas SnO 2 was successfully incorporated into SiO 2 structure (SnO 2 //SiO 2) by pyrolysis of solid-state mixtures of the precursors SnCl 2 •Chitosan in the presence of SiO 2 , the same reaction carried out with ZnCl 2 •Chitosan precursors led to a mixture of Zn 2 SiO 4 and SiO 2 The absorption and photoluminescence properties of the nanostructured SnO 2 //SiO 2 were very similar than those of pure SnO 2. Thus, this new methodology yields nanostructured semiconductor materials, ZnO and SnO 2 , suitable for optoelectronic and sensor solid-state devices.
A systematic study of the synthesis of V2O5nanostructured materials using macromolecular PS-co-4-PVP·(VCl3)yand chitosan·(VCl3)ycomplexes is presented. It is demonstrated that various coordination degrees of the metal into the polymeric chain specifically influence the product formation after pyrolysis. PS-co-4-PVP·(VCl3)yand chitosan·(VCl3)ycomplexes were prepared by simple coordination reaction of VCl3with the respective polymer in molar ratios 1 : 1, 1 : 5, and 1 : 10 metal/polymer and characterized by elemental analysis, IR spectroscopy, and TGA/DSC analysis. Solid-state thermolysis of these precursors at several temperatures under air results in nanostructured V2O5using all precursors. The size and shape of the nanostructured V2O5depend on the nature of the polymer. For the chitosan·(VCl3)yprecursors sub-10 nm nanocrystals are formed. The calcination process, involved in the preparation method, produces V2O5with photoluminescence in the visible light region, suggesting the possible application in oxygen sensing devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.