Growth of a superhydrophobic multi-walled carbon nanotube forest on quartz using flow-vapor-deposited copper catalysts

Abstract

Although studies on carbon nanotube (CNT) growth have made great advancements, direct growth of highly dense CNTs on desired substrates or positions remains an important challenge. Herein, we report a simple method to directly fabricate a CNT forest on a quartz surface using a copper catalyst at 850 °C under a stream of argon-diluted ethanol. Copper nanoparticles (NPs) are used as catalysts, which are generated through flow-vapor-deposition of copper (II) acetylacetonate on a thermal-treated SiO2 (quartz) or Si (silicon wafer) surface. Dense tangled CNT forms on the quartz surface. However, when a silicon wafer is used as the substrate, the only product is a carbon-covered copper NPs instead of CNTs. The growth yield of CNTs is approximately 10.5 g CNT/g Cu⋅h as characterized by thermogravimetric analysis, which is remarkably high compared with those achieved by conventional copper-based catalysts. The stronger metal-support interaction of copper NPs with quartz is suggested to be the key factor for CNT growth. Bamboo-like MWCNTs (BMWCNTs) are the main structures formed through transportation of copper NPs during CNT formation as evidenced by HR-TEM micrographs. Moreover, CNT-grown quartz has superhydrophobic features with a contact angle of 154°, revealing its promising application in self-cleaning coatings.