Application Properties Of Ag Naoclusters@SiO₂Materials

Nano-materials have been the subject of the research in the21century. Due to the special physicochemical properties, metal nanomaterials have attracted much more attention in the past decades. Among them, the nanoparticles of noble metal Ag are widely used for many applications because of its unusual optical, electric and magnetic characteristics. Silver nanomaterials mainly include silver nanoparticles and silver nanocomposites. We demonstrated the applications in catalytic, antibacterial, electrochemical properties of Ag nanoclusters@SiO2that is synthesized previously by our co-team workers. The main contents and results achieved in this paper were listed as follows:Firstly, the antibacterial performance of Ag nanoclusters@SiO2particles against Escherichia coli(E. coli), Staphylococcus aureus(s.. aureus) and Candida albicans(C. albicans) were tested using zones of inhibition, dilution and plate culture. The results show that it has the highest antibacterial activity on gram-negative bacteria, followed by gram-positive and C. albicans is the lowest. In the quantitative test, the minim inhibitory concentrations(MIC) toward E. coli and S. aureus are0.2mg/mL,0.3mg/mL and the minimum bactericidal concentrations(MBC) are0.3mg/mL,0.5mg/mL respectively. The antibacterial activity is also related to the size of silver particles, action time and concentration of sample. In addition, Ag nanoclusters@SiO2particles are more stable than pure AgNPs, resulting in long-term antibacterial effects.Secondly, we demonstrated the electrochemical behaviors of nitro-compounds and H2O2with the catalytic activity of Ag nanoclusters@SiO2particles. As expected, the resultant material showed excellent electrocatalytic activity to them and the detection of H2O2is0.48M. Moreover, they have higher sensitivity to the detection of nitroaromatic compounds than aliphaticnitro compounds. Compared with other methods, it is a fast, sensitive, reliable and simple manner.Finally, the catalytic activities were tested by catalytic reduction ofp-nitrophenol(p-NP) intop-aminophenol(p-AP) as model reaction with the method of UV-Vis spectroscopy. The results show that the Ag nanoclusters@SiO2particles display highly catalytic activity with p-nitrophenol conversion of98.8%by the2.0mol%at room temperature. Moreover, it remain excellent catalytic activity and can be reused six times after separation. The reaction constant suggested that the reaction followed pseudo-first-order kinetics with respect to p-nitrophenol. The apparentrate constant and the activation energy were estimated to be O.11min-1at298K and54.8kJ/mol, respectively.