Spray drying assisted assembly of ZnO nanocrystals using cellulose as sacrificial template and studies on their photoluminescent and photocatalytic properties

The conventional zincoxen cellulose solution, which was obtained by dissolving cellulose with the zincoxen solvent (tri(ethylenediamine) zinc hydroxide solution, Zn(EDA)(3)(2+)), has been used as raw materials for the preparation of zincoxen/cellulose complex microspheres via a spray drying technique. The obtained zincoxen/cellulose microspheres are turned into assemblies (or clusters) of ZnO nanocrystals by calcining the complex microspheres at 500 or 700 degrees C. For the preparation, zincoxen plays both the role as solvent for cellulose and precursor for the ZnO nanocrystals. While, the cellulose acts as assembly agent during the spray drying step and sacrificial templates in the calcinations process. The content of cellulose in the zincoxen cellulose aqueous solution and the calcination temperature show significant impacts on the morphology, porosity, optical properties and photocatalytic activity of the resulted ZnO nanocrystal assemblies. The structures, morphology and porosity have been investigated based on XRD, SEM, TEM and N-2 adsorption-desorption technique. The lattice parameters have been fitted by the Rietveld refinement and the strains in the crystals have been studied. Under ultraviolet light irradiation, all the assemblies of ZnO nanocrystals exhibit high photocatalytic activity for methyl orange degradation in aqueous solution and also satisfied reusability and stability of morphology and composition. (C) 2017 Elsevier B.V. All rights reserved.