SERS Of Au Nanorods And Photocatalytic Of Au@CdS Nanorods Properties Reasearch

Gold nanorods are anisotropic materials with unique optical properties and have been widely used in medical imaging,optical sensing,information storage,and photocatalysis.The surface plasmon resonance(SPR)wavelength of the gold nanoparticles lies in the absorption band of the visible spectrum region.Its SPR wavelength is not adjustable.The electrons on surface of the gold nanorods have different degrees of polarization in the longitudinal and transverse directions,respectively.Two resonant absorption peaks of gold nanorods will appear in the absorption spectrum.The longitudinal SPR of the gold nanorods can produce red or blue shifts as the aspect ratio(AR)changes.This means that we can obtain different SPR wavelengths by adjusting the aspect ratio of the gold nanorods.This provides the possibility of implementing surface-enhanced Raman scattering(SERS)substrates of different laser wavelengths.In addition,gold nanorods can be assembled into different arrangement mode gold nanorod superstructure by different methods.In view of the uniform arrangement of adjacent gold nanorods in the gold nanorod superstructure,a uniform and stable coupled electromagnetic field occurs,which means that this superstructure has good uniformity and repeatability when employing it as a SERS substrate.With the development of nanotechnology,the metal-semiconductor composite nanomaterials have attracted the attention of many scholars.This provides the possibility for the synthesis of highly active and stable catalysts.Compared with pure semiconductor materials,noble metal and semiconductor nanocomposites can significantly improve the catalytic performance.Since the morphology of the catalytic materials will affect the spatial distribution of photogenic electron hole and migration path of optical electronic,a reasonable aspect ratio needs to be designed to balance the speed at which photogenerated electron reach the interface.Due to the SPR tunable property of gold nanorods,they can be used in the synthesis of metal semiconductor composite materials.This can change the morphology of the composite materials and adjust the light absorption range in the visible light region.The photocatalytic performance of the metal semiconductor composite nanomaterials will be improved.In this paper,we prepared gold nanorods with different aspect ratios and high purity.The gold nanorods are assembled into two modes of gold nanorod superstructures.Combining the FDTD theory,the electromagnetic field coupling characteristics of gold nanorod superstructures with two arrangement modes are simulated and calculated.In addition,Au@CdS nanorods were prepared by coating gold nanorods with CdS semiconductor material.The optical and photocatalytic properties of Au@CdS nanorods were studied.The main research contents and research results are as follows:(1)Gold nanorods were prepared by the seed growth method.The aspect ratio of gold nanorods was adjusted by adding different amounts of reactants.The optical properties of gold nanorods were studied.The experimental results show that the SPR wavelength of gold nanorods can be adjusted by changing the their aspect ratio.(2)The gold nanorods were assembled into gold nanorod superstructure with arranged horizontally and vertically by evaporation of the solution.The gold nanorod superstructure was used as the SERS substrate and malachite green as the probe molecule to study the SERS activity of gold nanorods superstructure.The effect of different arrangement of gold nanorods on their SERS activity was studied.It is proved that the gold nanorod superstructure with parallel arrangement is an SERS wavelength-tunable SERS substrate material.(3)FDTD was used to simulate the electromagnetic field coupling of the gold nanorod superstructures with different arrangements,and the effects of different arrangement modes on the electromagnetic field coupling characteristics were studied.The theoretical calculation is consistent with the experimental results.In addition,it is proved that the different polarization directions of the laser have an effect on the coupled electromagnetic field intensity of gold nanorod superstructures with parallel arrangement.(4)The hydrothermal method was used to coat the surface of gold nanorods with CdS shells to form Au@CdS nanorods.The Au@CdS nanorods have a wide spectral range and have a stronge absorption of light compared with pure gold nanrods or CdS.(5)Au@CdS nanorods were used as photocatalysts to degradate rhodamine 6G to demonstrate stronge photocatalytic activity of Au@CdS nanorods.