Magneto-optical Coupling Properties Of CdSe/Co Multilayer Heterojunction Nanowires

One-dimensional semiconductor/metal heterojunction nanomaterials have attracted much attention and attention due to their bifunctionality,which has great potential application value in the fields of luminescence,catalysis,biomarker and fluorescence detection.This thesis focuses on one-dimensional semiconductor/metal multilayer heterojunction nanomaterials.For the first time,CdSe semiconductor and Co metal are prepared into one-dimensional heterojunction structure.Template method is used to assist electrochemical potentiostatic deposition to prepare CdSe/Co multilayer heterojunction,and explore the optical-magnetic dual function.Morphological characterization,composition characterization and structural characterization of CdSe/Co multilayer heterojunction nanowires were carried out.Characterization of optical and magnetic coupling properties of synthesized samples by UV-Vis,luminescence,Raman spectroscopy,and magnetometers,the main research contents are as follows:1.In the deposition solution of 0.2 mol/L CdSO₄,1mmol/L SeO₂,0.25 mol/L Na₂SO₄ and 0.15 mol/L dilute H₂SO₄,the suitable potential of the deposited Cd/Se atomic ratio of 1:1 was found by cyclic voltammetry is-0.65V;Co nanowires can be prepared at a deposition potential of-1.1 V in a deposition solution of 1 mol/L Co SO₄·7H₂O,40 g/L H₃BO₃.The morphology,composition and structure of the prepared one-component CdSe and Co nanowires were characterized.It was found that the nanowires grew along the pore walls of the AAO template,the diameter was the same as that of the template,and the height was long and straight and arranged in an array.The compositional characterization proves that the CdSe nanowires have a stable atomic ratio and there are no impurity elements in the two nanowires.The structural characterization indicates that the CdSe nanowires have a cubic sphalerite phase structure and grow along the<111>crystal orientation;Co nanowires have a face-centered cubic phase and a hexagonal phase structure,and grow along the<110>/<220>crystal orientation.2.The CdSe/Co multilayer heterojunction nanowires were prepared by alternately depositing CdSe and Co nanowires by double-groove method SEM characterization indicates that the heterojunction nanowires are alternately bright and dark with obvious delamination;XRD characterizes the heterostructure and found that the CdSe component still exhibits a cubic sphalerite phase structure in the multi-layer nanowires,while the Co component exhibits the same co-growth mode as the one-component Co,and grows preferentially along the<110>and<220>crystal orientations.3.The length of small Co fragments in CdSe/Co nanowires was adjusted,and the samples were optically characterized by UV-Vis,photoluminescence and Raman spectroscopy to explore the effect of magnetic metal Co embedding on the optical properties of semiconductor CdSe.In the heterostructure,the free electrons in the small fragment Co actively participate in the free electron oscillation in the CdSe nanowire,which induces the optical coupling effect,exhibiting the same optical properties as the one-component CdSe nanowires of the total length.In the Raman spectrum of the one-component CdSe nanowire,as the Co fragment grows,the LO peak under the CdSe/Co nanometer moves toward the low frequency direction.4.In the magnetic characterization,the length of the CdSe fragment embedded in the Co nanowire is adjusted.When the total length is the same,the embedding of the small fragment CdSe nanowire does not affect the coercivity of the total nanowire,indicating the intervention of CdSe at this time.The Co nanowires with longer ends have magnetic coupling.When the CdSe fragment grows,the Co nanowires exhibit the same coercivity as the Co of the same length of the single component,indicating that the magnetic coupling is lost at this time.