One Dimensional Inorganic Nanomaterials Embedded In Anodic Alumina Membrane By A Hydrothermal Method With Double Diffusion

In recent years, the preparation of one-dimensional inorganic nanomaterials hasreceived much attention. For example, ZnS as the transition metal sulfides, has beenwidely applied in the fields of chemical, optical and semiconductor. As the size of theparticles decreasing, nano-materials of ZnS show some special characters verydifferent from their bulk materials, which have an important impact on photochemical,electrical and nonlinear optical properties. LiFePO₄, as a kind of lithium-ion batterymaterials, with a large discharge capacity, low cost, non-toxic, less environmentalpollution, etc., has attracted the attention of many experts and scholars.The method of synthesis for one-dimensional inorganic nanomaterials can bedivided into gas-phase, liquid phase method and template method, by the growthmechanism characterized. The template method includes a method of using the anodicaluminum oxide membranes to grow one-dimensional nanomaterials in the holes. TheAAO template has the characteristics of high pore density, the uniform pore size andthe adjusting hole size, etc.Herein, a new synthesis method of AAO template with double diffusion throughhydrothermal has been studied, to synthesize zinc sulfide nanowires andone-dimensitional nanostructures of lithium iron phosphate.AAO template was synthetized by two anode oxidation method. The equimolaramount of sodium thiosulfate and zinc acetate were dissolved with appropriateamount of deionized water, respectively. AAO template was placed in the middle of aself-designed Teflon-lined, then the above two solutions were instilled in both sides ofthe template to make sure they spread with each other only through the middle of thetemplate. The product were characterized by X-ray diffraction （XRD）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM） otheranalytical testing methods. We investigate the double diffusion process by contrastingthe surface analysis of EDS and morphology analysis of SEM. The as-obtained ZnSnanowires, which were only synthesized in the holes of the template, had a uniformdiameter of about60nm, with regular spread. It was consistent with the size of theAAO pores, that confirmed the significant spatial limitations induced by the AAOtemplate on the nanorod arrays.Lithium acetate, phosphoric acid, ferrous sulfate and ascorbic acid were added inboth sides of the self-designed Teflon-lined, to make sure both sides spread with eachother only through the middle of the template. The one-dimensitional nanostructuresof LiFePO₄were synthesized, and the remaining products of the reactor were notLiFePO₄. The obtained one-dimensitional nanostructures of LiFePO₄were somemultiple crystal structures whose edges and corners were clearly demarcated. Theywere spread regularly with a diameter of about60nm, that proved the diameter of theas-obtained products were determined by the diameter of the AAO template.By changing the time of hydrothermal and the concentration of reactants, itsimpact on the products was explored. Changing hydrothermal time had no effects onthe morphology of the products, and less impact on the rate of diffusion of zinc andsulfur. When the concentration ratio of zinc source and sulfur source was1:1, the rateof zinc was less than sulfur. When the concentration of zinc source was less thansulfur source, the distribution of zinc in the product was more sparse, which made thedistribution of sulfur in the product also become sparse. When the concentration ofsulfur source was less than zinc source, the distribution of sulfur in the productbecame sparse, but the distribution of zinc in the product was essentially the same.Changing the concentration of zinc source can affect the distribution of sulfur in theproduct, but Changing the concentration of sulfur source had no effect on thedistribution of zinc in the product.