Controlled Synthesis And Performances Of Ag Nanocrystals By Thio-functionalized Ionic Liouid

In recent years, noble metal nanomaterials have received ever intensive attention owing to theirdistinct physicochemical properties and applications, and various ligands including organics andbiomoleciles have been used to prepare the metal nanoparticles. However, some of these ligands can bringa great deal of pollution to the environment, and usually request the harsh reaction conditions. In this work,1-(10-mercaptodecyl)-3-methylimidazolium bromide ([HS-C10mim]Br) was employed as a “green”stabilizer to prepare monodisperse silver nanoparticles. The as-synthesized silver nanoparticles werecombined with rhodamine6G to obtain a fluorescent nano-sensor of Hg2+, and further their catalyticproperties were studied in chemical reactions. The main contents include as follow:1. The spherical silver nanoparticles about5nm in diameter were synthesized using thiol-functionalized ionic liquid as ligand in aqueous solution at298K. Compared with conventional ligand,silver nanoparticles capped by thiol-functionalized ionic liquid have strong hydrophilic, and greatlyimprove the stability with long shelf-time due to the affinity of thiol groups toward Ag surfaces. For thesynthesis of silver nanoparticles, the temperature of298K is relatively low, unlike the traditional synthesisat high temperature. Therefore, the work reported a feasible method using the thiol group functionalizedionic liquids as ligand to synthesize monodisperse silver nanoparticles with the mild reaction conditions,simple operation, and small size.2. The silver nanoparticles combine with rhodamine6G(Rh6G) to produce easily the AgNPS-Rh6Gnanocomposite fluorescent probe, and the probe can be used to detect mercury ions(Hg2+) in aqueoussolution by fluorescence spectroscopy. The experimental results show that the nanocomposite sensors isvery sensitive to Hg2+with the detection limit of10-13mol/L at pH=2.0. The detection limit is about1000times higher than that reported previously in the literature. Moreover, the sensors have very high selectivityand specificity to Hg2+.3. The as-synthesized silver nanoparticles were employed as a catalyst in reductionof sodiumborbhydride to P-nitrophenol, and the reaction process was monitored by UV-visible spectroscopy. It wasshown that thiol-functionalized ionic liquid capped-silver nanoparticles have very high catalytic activitywith a factor of2834s-1·g-1. To our knowledge, it is the best catalyst for this reaction reported. It is noted that the content of free ionic liquid exerts a great influence on the reaction rate. The free ionic liquid willkeep from the reactants to access the catalyst, and thereby the rate of the catalytic reaction is reducedsignificantly.