Fabrication Of Heterostructures By Ion Exchange Using ZnO Template

Ion exchange is a versatile method to engineer nanomaterials. It can be used tocontrol the morphologies, composition and structure of nanomaterial, especially somenon-equilibrium nanostructures. Ion exchange in the gas phase can produce highcrystallined nanomaterials, and ion exchange in solution is very facile and simple. Onthe other hand, ZnO nanomaterial can be obtained in aqueous solution easily and it isan environmental friendly material which can be used as template for ion exchange,resulting in1-D and2-D heterostructures base on ZnO nanomaterial. The main resultsare as follows:Firstly, we fabricated ZnO/ZnSe heterostructures by gas phase anion exchange inSe vapor. We systematically investigated the influence of temperature, Seconcentration, reaction time on the formation of ZnO/ZnSe heterostructures. Thelowest reaction temperature was determined as500°C, and the amount of Se powderaffects the morphology and shell thicknes of the final ZnO/ZnSe heterostructures. Wealso studied the relationship of the diamater of the start ZnO nanorods with finalproducts, and found that pure ZnSe and ZnO/ZnSe heterostructures can be generatedby using thin or thick ZnO nanorods as templates, respectively. It is proposed that theanion exchange proceeds as a result of outdiffusion of ZnO. We also found thatintense light emission of ZnO/ZnSe heterostructures at505nm orgininates from Znvacany during anion exchange reaction.Secondly, we successfully fabricated ZnO/ZnSe/PbSe heterostructures by gas phasecation exchange using ZnO/ZnSe heterostructures as a template. And it is possible totansform ZnSe layer into PbSe completely by adjusting reaction temperature and time.The as-obtained products are well-crystallined and promising nanomaterials insolid-state solar cells.Thirdly, we constructed a two-dimensional ZnO/CdSe heterostructure nanosheetusing ZnO nanosheet as a template. ZnO/CdSe heterostructure nanosheets possesshuge specific surface and own a type-II band structure, which is promosing forphotocatalysis application.