Synthesis, characterization, and properties of metallic copper nanoparticles
Synthesis, characterization, and properties of metallic copper nanoparticles
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DOI：
10.1021/cm9708269
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发表时间：
1998-05-01
影响因子：
8.6
通讯作者：
Gedanken, A
中科院分区：
文献类型：
--
作者：
Dhas, NA;Raj, CP;Gedanken, A
采用热还原法和超声化学还原法制备了金属铜簇合物Cu（N2 H3COO）（2）。2 H（2）O络合物。两个还原过程都在氩气气氛下进行2-3小时。FT-IR、粉末X-射线衍射和紫外-可见研究支持Cu 2+离子的还原产物为金属铜纳米晶。热衍生产物的粉末X射线分析显示纯金属铜的形成，而声化学方法产生金属铜和氧化铜（Cu 2 O）的混合物。Cu 2 O沿着铜纳米粒子的形成是由于在声化学条件下原位生成的H2 O2对铜的部分氧化。然而，存在的混合物ee氩/氢（95：5）气氛产生纯铜金属纳米粒子，这可能是由于清除作用的氢对OH。在超声波照射过程中在溶液中产生的自由基。所合成的铜纳米粒子在550- 650 nm范围内具有明显的吸收峰。热衍生铜的透射电子显微镜研究显示存在具有尖锐边缘和小平面的不规则形状的颗粒（200-250 nm）。另一方面，声化学衍生的铜粉显示出含有小纳米颗粒的不规则网络的多孔聚集体（50- 70 nm）的存在。铜纳米颗粒对“乌尔曼反应”具有催化活性，即芳基卤化物的缩合达到80-90%的转化率。研究了碘苯缩合反应的催化时间过程，反应温度为200 ℃，反应时间为1-5小时。比较了热化学法和声化学法制备的纳米铜粉与市售铜粉的催化性能。
Nanoscale particles of metallic copper clusters have been prepared by two methods, namely the thermal reduction and sonochemical reduction of copper(II) hydrazine carboxylate Cu(N2H3COO)(2) . 2H(2)O complex in an aqueous medium. Both reduction processes-take place under an argon atmosphere over a period of 2-3 h. The FT-IR, powder X-ray diffraction, and UV-visible studies support the reduction products of Cu2+ ions as metallic copper nanocrystallites. The powder X-ray analysis of the thermally derived products show the formation of pure metallic copper, while the sonochemical method yields a mixture of metallic copper and copper oxide(Cu2O). The formation of Cu2O along with the copper nanoparticles in the sonochemical process can be attributed to the partial oxidation of copper by in situ generated H2O2 under the sonochemical conditions. However, the presence of a mixture of ee an argon/hydrogen (95:5) atmosphere yields pure copper metallic nanoparticles, which could be due to the scavenging action of the hydrogen towards the OH. radicals that are produced in solution during ultrasonic irradiation. The synthesized copper nanoparticles exhibit a distinct absorption peak in the region of 550-650nm. The transmission electron microscopy studies of the thermally derived copper show the presence of irregularly shaped particles (200-250 nm) having sharp edges and facets. On the other hand, the sonochemically derived copper powder shows the presence of porous aggregates(50-70nm) that contain an irregular network of small nanoparticles. The copper nanoparticles are catalytically active toward an "Ullmann reaction"-that is, the condensation of aryl halides to an extent of 80-90% conversion. The time course of catalysis was studied for condensation of iodobenzene at 200 degrees C for a period of 1-5 h. The catalytic ability of copper nanoparticles produced by the thermal and sonochemical methods was compared with that of commercial copper powders.