Controllable Preparation Of Small Size Monodisperse Silver Nanocrystals

Silver nanoparticles is an advanced functional material,Because of its small size effect,surface effect,quantum size effect,dielectric limitation and other common characteristics of all nanomaterials,it has potential applications in optoelectronic,biosensor,catalysis,antibacterial and other fields.However,the properties of silver nanoparticles are usually determined by their size,shape and surrounding medium,which can be adjusted by various synthetic methods.A large number of literatures have reported on the synthesis method of nano-silver.However,the synthesis of small-sized nano-silver particles still has some disadvantages such as uneven size distribution,poor dispersion,easy agglomeration,and poor stability.Applications.This thesis has comprehensively studied the influence of different factors on the synthesis of silver nanoparticles.On the basis of traditional inverse microemulsion,the original method of single micelle inverse microemulsion method for preparing silver nanoparticles has been created.Small-size monodisperse silver nanoparticles,and explored its degradation effect on methylene blue,the degradation rate reached 98% within 2h,which was significantly improved from the reported literature.The main findings are as follows:(1)Stable and controllable AgNPs was successfully prepared by traditional inverse microemulsion method(water / AOT/ isooctane).The experimental results can be greatly affected by changing different experimental conditions,such as adjusting the ratio of water to surfactant(? = 5:1,6:1,7:1,10:1),using different reducing agents,different silver sources,etc.The results show that under the condition of ascorbic acid as reducing agent and silver trifluoroacetate as silver source,the particle size of silver nanoparticles can be controlled between 3 and AOT by adjusting the molar ratio of water to 10 nm.(2)In order to solve the problems of non-uniform size distribution,poor dispersion,easy agglomeration and poor stability of silver nanoparticles,a single micelle inverse microemulsion method was developed to prepare small monodisperse silver nanoparticles.Based on the traditional inverse microemulsion method,silver nanoparticles with small size(3nm?6.8nm),uniform distribution and stable dispersion were obtained by changing the double micelle system into a single micelle system,using ascorbic acid as reducing agent and sodium dioctyl succinate sulfonate as surfactant.(3)Based on the synthesized silver nanoparticles,the properties of luminescence and photocatalytic degradation were explored.The optical properties were tested by transient-steady-state fluorescence spectrometer.The blue light emission peak of 427 nm was obtained by the prepared silver nanoparticles excited by 354 nm,which is rare in the reported literature.Finally,using silver nanoparticles of 10mg/L as catalyst,methylene blue can be degraded by 98% within 2 hours,which is significantly higher than that of silver nanoparticles synthesized by other methods reported.