Preparation, Characterzation And Photothermal Properties Of Ag/Ag₂S Nanomaterials

Photothermal conversion materials are very attactive due to their applications in the collection of solar energy and medical treatment. Precious metals and its vulcanized products have high photothermal conversion efficiency, good biocompatibility and have great significance in the research of photothermal coversion materials.Well dispersed silver and silver sulfide nanoparticles were separately synthesized through chemical method, and silver/silver sulfide core-shell nanostructure can be synthesized on the basis of silver nanoparticles after sulfuration reaction. Then XRD, TEM, SEM were employed to study the impact of experimental conditions on the product structure. Furthermore, UV-Vis-NIR spectrometer and photothermal evaluation were applied to analyze the optical and photothermal performance of the products.The results are as follows:(1)Well dispersed silver particles with different sizes were synthesized through a wet chemical method where AgCl sol was reduced by Vitamin C to yield silver particles in alkaline condition, with PVP-K30as dispersant. Photo-thermal conversion effects of the as-synthesized products were evaluated on a lab-mode system equipped with an AUT-FSL semiconductor/solid state laser. The results showed that silver nanoparticles with size of30,50,75and100nm can be synthesized by adjusting the pH values of the reaction systems. Silver particles of120,150and200nm can be synthesized through a two-step growth method with50nm silver nanoparticles as seeds. Dispersed in water, all silver particle samples with different sizes exhibit significant photo-thermal conversion effect enhancement under irradiation of635nm and1064nm laser. The photo-thermal conversion efficiency is proved to increase with decreasing particle size.(2)Silver sulfide nanoparticles were synthesized through precipitation transforming method with AgNO3as reactant and PVP-K30as dispersant. Well dispersed Ag2S nanoparticles with small particle size can be prepared by adjusting the reactant concentration, the precursor types and the sulfur sources. The results indicate that well dispersed Ag2S nanoparticles with particle size of about50nm can be synthesized when AgCl and CH3CSNH2are chosen to be the silver source and the sulfur source respectively, with a reactant concentration of0.05mol·L-1and a reaction time of3h. The product exhibits fairly well property of light absorption in visible and nera infrared bands. The absorption of light and photothermal properties is proportional to the solid content and the laser power.(3)Silver/silver sulfide core-shell nanostructure can be synthesized on the basis of silver nanoparticles after interface sulfuration reaction. The influence of different reaction conditions on the product, and the light absorption and photothermal properties of the samples were studied. The results show that the thioacetamide is the most appropriate sulfur source, the shell thickness of samples increases as the extension of reaction time, and the optical properties of the sample analysis showed that the light absorption properties of core-shell nanostructure is stronger than before vulcanization of elemental silver nanoparticles, the photothermal conversion effect of core-shell nanostructure is higher than it of silver nanoparticles.