| Cadmium sulfide(CdS)is an important class of II B-VI A compounds.It is a classical direct band gap semiconductor with a band gap of 2.42 e V(300 K).CdS is widely used in solar cells,light-emitting diodes,photocatalytic materials,lasers,electronic and optoelectronic devices and other fields due to its unique photochemical activity and strong visible light absorption.CdS is also an important gas sensing material and surface enhanced Raman scattering(SERS)substrate.It can be used to detect harmful organic volatile gases and low concentration chemical additives in the environment,but there are few related studies.Based on this,the micro hollow spheres and nanowire arrays of CdS were prepared,and their gas sensitive as well as surface enhanced Raman properties were studied,and the performance was improved,which provided a certain reference for subsequent research.The research contents are as follows:Firstly,CdS micro hollow spheres(MHs)were prepared.It is found that CdS MHs material is hexagonal wurtzite structure,which is self-assembled from CdS nano sheets via the characterization and analysis of scanning electron microscope,X-ray diffraction,photoelectron spectroscopy and high-resolution electron microscope.It is made into a gas sensor to test and analyze the gas sensing response of various alcohols and expand its application because CdS MHs has a large specific surface area and rough surface,which is helpful to adsorb gas.The optimum working temperature of CdS MHs gas sensor is 190?.At the optimum working temperature,its responses to 100 ppm ethanol and 100 ppm isopropanol are 27.4 and 84.55,and the lowest detection threshold is 98 ppb and 13 ppb respectively,indicating that it exhibits good gas sensing characteristics.It is further revealed that CdS MHs gas sensor has good anti-interference ability by the gas sensing test of the mixture of isopropanol(isoamyl-alcohol)and acetone or isopropanol(isoamyl-alcohol)and methanol.Therefore,CdS MHs gas sensor is suitable for monitoring alcohol volatile gases.Secondly,CdS nanowire arrays were prepared by hydrothermal method.It is found that the material has good uniformity by SEM,XRD,photoelectron spectroscopy and HRTEM.It is necessary to decorate precious metals to improve the performance because of the poor SERS effect of semiconductor.Hence,a small ion beam sputtering instrument is used to sputter Au film on the surface of CdS nanowire arrays,which is annealed at 300?in vacuum for two hours to form CdS@Au nanowire arrays.The dye molecule(Rhodamine B)was selected as the probe molecule,and the SERS performance of CdS@Au nanowire arrays was investigated.The actual minimum detection limit of Rhodamine B was 1.0×10-7 mol/L,and the SERS performance was significantly promoted.It was three orders of magnitude better than that of CdS nanowire arrays and one order of magnitude better than that of Au nanoparticles.The relative standard deviation(RSD)of the substrate at 1359,1508 and 1649 cm-1characteristic peaks of Rhodamine B are 9.13%,9.82%and 9.16%respectively,revealing that the substrate has strong uniformity.In order to extend its application range,SERS tests were carried out on crystal violet and malachite green,and the actual minimum detection limit was 1.0×10-5 mol/L.Therefore,CdS@Au nanowire arrays can be used as SERS substrates to detect carcinogens in aquatic products and synthetic dyes. |
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