| In this paper, silver nanorods and nanoplates have been synthesized by means of ultrasonic irradiation, with fusibility silver salt and a certain concentration of reducing agent and stabilizer in aqueous solution; And when we use the same silver source, reducing agent and stabilizer, but change the system to water / ethanol solution (1:1), a special morphology micro/nanotubes of silver was prepared. The process of growing can be monitored by transmission electron microscopy (TEM) and scanning electron microscope (SEM). The products were characterized by selected area electron diffraction (SAED), X-ray diffraction (XRD), IR spectrophotometer and energy dispersive spectra (EDS). This is the first time to synthesis silver nanorods and nanoplates using sonochemical method, and the preparation of large-size silver microtubes have not been reported whether at home or abroad.Silver nanorod: The reaction solution contains stabilizer PVP 0.40 g /L,reducing agent HMTA 0.80 g /L and silver source AgNO3 0.01 mol /L, under the conditions of constant temperature and ultrasonic irradiation, silver nanorods with uniform morphology was prepared, with average length of 6μm and diameter of 50 nm. We use transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray to characterize the morphology of silver nanorods. At the same time, the impact of the reaction time, stabilizer and reaction temperature on the silver nanorods morphology had been discussed. The experiment shows that the length of silver nanorods is increasing as the reaction time increased, and becoming shorter when the stabilizer concentration increased. The reaction mechanism is proposed by IR analysis.Silver nanoplates: In the above reaction system, we maintain the concentration of silver nitrate of 0.01 mol / L, reducing the concentration of reductant(HMTA 0.20 g/L), while increasing the concentration of stabilizer(PVP 0.60 g/L), then ultrasonic irradiation for 30 minutes at the temperature of 30℃, the silver nanoplates of 200- 280 nm in diameter were prepared. It shows that under the conditions of low concentration of reducing agent, the growth of silver nuclei was inhibited by high concentrations of stabilizing agent, and eventually grows into a plate with smooth surface. With the concentration of PVP stabilizer increasing, nanoplates regularly to become smaller in diameter, which can control the diameter and the size of silver nanoparticles; The paper also examines the effect of reducing agent and medium acidity on the morphology of silver nanoplates. In addition, silver nanoparticles have good antibacterial properties, the results showed that the minimum inhibitory of silver nanoparticles concentration is 8μg /mL.Silver micro/nano-tubes: In this study, we use silver nitrate as silver source, HMTA as the reducing agent, PVP as stabilizer to prepare silver colloid in the organic system of water/ethanol (1:1) under the conditions of constant temperature 30℃and ultrasonic irradiation for 30 min. After 6 days aging at 4℃, the silver microtubes were formed. The silver microtubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). By changing the aging time, stabilizer type, concentration of reducing agent, medium pH and ultrasound treatment, we investigated the morphology differences of silver microtubes. The results showed that it is a self-assembly process to form silver micro/nano-tubes, its length and shape are affected by the reducing agent concentration, stabilizer type, pH value and aging time. When we use stirring instead of ultrasound, the morphology of the silver tubes were heterogeneity.
|
PDF Full Text Request