以小分子型诱导剂液相还原制备铜纳米片

Synthesis of copper nanoplates via a small molecule inducer assisted chemical process

在次亚磷酸钠-硫酸铜溶液的反应体系中加入小分子型诱导剂,制备了高径厚比的铜纳米片,并将其分散于丙烯酸/环氧复合树脂中制成导电胶。通过X射线衍射(XRD)、扫描电子显微镜(SEM)表征铜纳米片的结构与形貌,采用电阻测试仪测定导电胶的导电性能,研究了诱导剂种类及浓度、反应体系的p H值对铜纳米片形貌的影响,并分析了铜纳米片的形成过程。结果表明:诱导剂胸腺嘧啶的加入及合适的p H是制备铜纳米片的关键;胸腺嘧啶的浓度及p H过低或过高时,均会导致产物中片状铜粉比例减少,颗粒状铜粉比例增加。获得高质量的铜纳米片的最佳条件为:胸腺嘧啶的浓度1.5 mmol/L,p H 1.5,反应时间2 h。此条件下所得的铜纳米片表面平整,厚度为50~100 nm,直径约为15μm,以此铜纳米片制得的导电胶比球磨法片状铜粉制成的导电胶有着更好的导电性。

Copper nanoplates have potential applications in conductive adhesives,conductive paste and other fields. Mechanical milling is the prevailing process in manufacturing flake copper powders,but the dimensions and morphology of the Cu powder particles cannot be controlled because cold welding between particles often occurs.Furthermore,nanoplates cannot be obtained by this process. More and more attention has therefore been paid to chemical processes for the preparation of nanoscale flake copper powders. However,the literature shows that it has been difficult to obtain nanoplates with high aspect ratio because the area of the flake increases with its thickness.In this paper,a new chemical approach is described,in which copper sulfate was chemically reduced by sodium hypophosphite in aqueous solution containing different structure inducers,namely 1 H-benzotriazole（ BTA）,guanine and thymine,to synthesize copper powders with different morphology and particle size. By X-ray diffraction（ XRD） and scanning electron microscopy（ SEM）,the effects of different structure inducers,thymine concentration,and p H value of the solution on the structure and morphology of Cu powder have been investigated in detail,and the growth process of the Cu nanoplates was studied. Conductive adhesives were obtained by combining the asprepared copper powder with an acrylic acid/epoxy composite resin and their conductivity determined using a resistance meter. The results show that the addition of thymine at an appropriate p H value results in the formation of large size and ultra-thin Cu nanoplates,while the addition of BTA or guanine did not. The percentage of Cu nanoplates in the synthesized product is closely related to the p H value and concentration of thymine in the reaction system. Under the optimized conditions—a concentration of thymine of 1. 5 mmol/L,a p H value of 1. 5,and a reaction time of about 2 h—copper powder with a particle diameter about 15 μm,thickness of 50-100 nm and aspect ratios about 190 have been obtained. The resulting Cu nanoplates afforded composite resins with higher conductivity than those prepared using plate copper powders obtained by ball milling.