Research On Self-assembly Of Triangular Silver Nanoplates And Their Optical Properties

Silver nanostructures have received great attention owing to their intriguing properties and potential applications in a number of areas including magnetics,photovoltaics and optics.Silver nanomaterials with different morphologies,sizes and functions have been gradually synthesised by researchers and triangular silver nanoplates are increasingly favored by them.The preparation of high-yield and reproducible triangular silver nanostructures is of great significance for the study of silver nanomaterials.Researchers always want to manipulate nanostructured units flexibly and efficiently.In recent years,self-assembly techniques have become a common method for constructing ordered structures on the nanometer and the micrometer scale through non-covalent bonds.Therefore,in this paper,face-to-face assembled triangular silver nanoplates were obtained by van der Waals attraction and the optical properties of triangular silver nanoplates were theoretically simulated by the finite difference time domain?FDTD?method.The main research work is performed as follows:Through adjusting of the experimental conditions,silver nanomaterials with different shapes and sizes can be obtained,such as the amount of reagents or the preservation environment.The best preparation process of triangular silver nanoplates was obtained after the products were characterized by TEM,SEM and UV-vis.The key operation of the triangular silver nanoplates was to be statically preserved after adding sodium borohydride.The triangular silver nanoplates solution was centrifuged and stationary for one week.The triangular silver nanoplates were assembled into face-to-face.The results showed that the assembled silver nanoplates were linked to the chain structure through the characterization of TEM and SEM.The main force of this assembly is the van der Waals attraction between the surfaces of the nanoplates.By comparing the extinction spectra of assembled and monodispersed triangular silver nanoplates,we can find the differences of the optical properties between them,which,in-plane dipole extinction peak of assembled triangular silver nanoplates has a blue shift.The theoretical simulation of their optical properties by using the FDTD showed that the theoretical and experimental results have the same variation tendency of optical properties,but the extinction peak of theoretical simulation has a greater blue shift than the experimental result.By simulating more actual assembly conditions,such as differences in size between nanoplates,displacements and rotations between nanoplates,the results showed that the difference in the magnitude of blue shift is due to face-to-face incomplete overlap caused by these existing realities.The monodispersed and assembled Ag-Ag₂S nanostructures were obtained by sulfuration reaction respectively,and the photocatalytic degradation of organic dyestuff methylene blue under visible light irradiation by monodispersed and assembled Ag-Ag₂S were tested.The results showed that the photocatalytic efficiency of the assembled Ag-Ag₂S hybrid nanostructure is up to 98.4%,which has a good photocatalytic effect.