还原-保护法制备纳米级银粉的研究

以氰化银钾 KAg(CN) 2 ]为原料 ,抗坏血酸为还原剂 ,聚乙烯吡咯烷酮为保护剂和分散剂 ,将还原剂和保护剂在反应体系之外预混合 ,然后滴加到KAg(CN) 2 溶液中 ,制备出粒径分布范围为 2 0～ 30nm的银粉 ,分散剂加入到还原剂中预先混合所得银粉的平均粒径约为分散剂预先加入在原料体系中所得银粉平均粒径的 1 14,在反应温度为 35 3K前随着反应温度的增加银粉粒径逐渐减小 ,超过 35 3K后银粉粒径随反应温度的增加而增加 ,在 35 3K时反应所得银粉的粒径最小。固定还原剂和原料浓度之比 (4 9∶1 0 ) ,在其他条件相同时银粉粒径随着反应物浓度的增加而增加。反应所得银粉用油酸钝化 ,可有效地防止银粉的氧化。用透射电镜 (TEM)和紫外 -可见分光光度计 (UV -Vis)等测试手段对所制得的纳米级银粉进行了表征

Preparation of Ag Nano powder by Reduction protection Method

In this paper,we report a simple and clean method for producing uniform colloidal silver nanoparticles by reduction of potassium silver cyanide KAg (CN) 2] using premixing and passivation techniques.Te reducing agent vitamin C (Vc) was mixed with the protective agent polyvinylpyrrolidone(PVP) prior to dropping into the solution of KAg(CN) 2.Reduction of KAg(CN) 2 took place easily in the premixing system.Average size of silver particles formed by this method was about 20 to 30 nm,about 1/14 of those by traditional method, and could be controlled effectively by changing the reduction conditions.The particle size decreased with the rise of reaction temperature before 353 K and increased after 353 K.When other conditions were identical,the particle size increased with the increase of concentrations of reactants.A passivating agent oleic acid was used to passivate the nanoparticles.The silver powder was characterized by transmission electron micrograph (TEM) and UV-vis spectroscope as well.