Controlled Chemical Transformation Of The Inorganic-organic ZnSe-DEAT Hybrid Nanosheets

Novel applications of nanostructures in catalysis, electronics, photonics andbionanotechnology are driving the exploration of synthetic approaches to control andmanipulate the morphology and chemical composition of nanostructures. Amongthese nanomaterials, hollow skeleton-like structures and hierarchical nanostructureshave attracted increasing interest owing to their unique structures, interestingproperties, which are different from their solid counterparts, and promisingapplications in different fields. As well as the design of synthetic strategies to producea new class of nanoscale materials, recent developments have enabled the chemicaltransformation of one crystalline material into another desired target material.Although great achievements have been achieved on the chemical transformation ofnanomaterials, the synthesis of frame-like or hierarchical inorganic mateials stillremain a great challenge.In this thesis, we adopted the inorganic–organic hybrid nanosheets as startingmaterials and utilized the facile cation-exchange strategy and the stabilizer-depletedmethod to fabricate hollow CdxZn1-xSe nanoframes and inorganic hierarchical ZnSemicrospheres, respectively. The morphology, composition and structuralcharacteristics of the products were systematically studied by SEM、EDX、TEM、XRD、 FTIR. In addition, we have demonstrated the detailed transformationmechanism of the reactions by performing the time-dependent experiments. Thesubsequent studies show that the as-prepared inorganic CdxZn1-xSe nanoframes andhierarchical fractal ZnSe microspheres exhibit outstanding performance in thephotocatalytic activities under irradiation of visible-light. The main contents of thispaper are listed as follows:1. We report a facile and effective protocol to prepare CdxZn1-xSe nanoframesthrough the selective cation-exchange reaction of unpurified inorganic-organicZnSe-DETA nanosheets with Cd2+ions. We show that CdxZn1-xSe nanoframes withadjustable composition are accessible by varying the relative ratio of hybridprecursors to cations in this approach. Moreover, the selective cation-exchangestrategy of hybrid nanosheets is suitable for fabricating other frame-like nanostructures. Furthermore, we demonstrate that the as-prepared Cd0.33Zn0.67Senanoframes are highly active for photocatalytic H2evolution from water splitting. Thecomposition of hollow CdxZn1-xSe nanoframes has exerted an important influence ontheir photocatalytic activities.2. We once again adopted the inorganic–organic ZnSe–DETA hybridnanosheets as starting materials and utilized a facile and effective stabilizer-depletedmethod to prepare inorganic ZnSe nanosheet-based hierarchical microspheres inhydrothermal solution. We show that ZnSe hierarchical nanospheres can besynthesized on large scale with no difficulty by tuning the concentration of DETA inthe solution. Moreover, this organic-component depletion method of hybridnanosheets is also suitable for fabricating hierarchical nanosphere-like nanostructuresof other sulfides and selenides. The subsequent study show that the as-preparedinorganic hierarchical fractal ZnSe nanoflowers with perfect crystallinenanostructures exhibit outstanding performance in the photocatalytic activities for thedegradation of methyl orange and photocatalytic hydrogen production.