Effects of two purification pretreatments on electroless copper coating over single-walled carbon nanotubes

Abstract

To achieve the reinforcement of copper matrix composite by single-walled carbon nanotubes, a three-step-refluxing purification of carbon nanotubes sample with HNONaOH-HCl was proposed and demonstrated. A previously reported purification process using an electromagnetic stirring with HHCl mixture was also repeated. Then, the purified carbon nanotubes were coated with copper by the same electroless plating process. At the end, the effects of the method on carbon nanotubes themselves and on copper coating were determined by transmission electron microscope spectroscopy, scanning electron microscope spectroscopy, X-ray diffractometry, thermogravimetric analysis, Fourier transformed infrared spectroscopy, and energy dispersive spectrometry. It was clearly confirmed that both of the two processes could remove most of iron catalyst particles and carbonaceous impurities without significant damage to carbon nanotubes. The thermal stability of the sample purified by HHCl treatment was slightly higher than that purified by HNONaOH-HCl treatment. Nevertheless, the purification by HNONaOH-HCl treatment was more effective for carboxyl functionalization on nanotubes than that by HHCl treatment. The Cu-coating on carbon nanotubes purified by both purification processes was complete, homogenous, and continuous. However, the Cu-coating on carbon nanotubes purified by HHCl was oxidized more seriously than those on carbon nanotubes purified by HNONaOH-HCl treatment.