The Effect of Substrate and Catalyst Properties on the Growth of Multi-Wall Carbon Nanotube Arrays
- PDF / 1,341,041 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 0 Downloads / 199 Views
0900-O12-16.1
The Effect of Substrate and Catalyst Properties on the Growth of Multi-Wall Carbon Nanotube Arrays Sudheer Neralla, Sergey Yarmolenko and Jag Sankar Mechanical and Chemical Engineering, North Carolina A&T State University, Greensboro, NC Vesselin Shanov, Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH Yeo Heung Yun and Mark J. Schulz Mechanical, Industrial and Nuclear Engineering, Smart Materials Nanotechnology Laboratory, University of Cincinnati, Cincinnati, OH Abstract Self-aligned arrays of long multi-walled carbon nanotubes (MWCNT) were grown by chemical vapor deposition (CVD) from a gas mixture of C2H4-H2-Ar-H2O at 750°C. A catalytically active alumina surfaces coated with a thin layer of iron and supported by a Si/SiO2 substrate were prepared using pulsed laser deposition method. Combinatorial approach has been used for optimization of catalytic properties of the multilayered system Si/SiO2/Al2O3/Fe. Sixteen different combinations of catalytic surfaces having thicknesses of Fe (0, 1, 2, and 3 nm), alumina (0, 10, 20 and 30 nm) per sample were deposited on two Si/SiO2 substrates with silica thickness 150 and 500 nm. To study the effect of alumina phase on efficiency of catalytic surfaces two substrate temperatures 200 and 700ºC were used to produce amorphous and γ-alumina phases correspondingly. This approach allowed the optimal structure of catalytic surface to be determined from 64 different substrates on 4 samples in a single MWCNT growth experiment, for a given set of processing conditions. It was found that most efficient growth of MWCNT arrays on amorphous alumina occurred at Fe nanolayer thickness of 2 nm while catalyst having γ-alumina layer has tendency to be more efficient at higher thickness of Fe. Catalytic substrate containing amorphous alumina has less sensitivity to thickness of iron while γ-alumina based catalyst has significant variation in catalytic activity with change of iron content. Introduction The increasing interest in the synthesis and applications of carbon nano tubes (CNTs) can be attributed to their unique structures and properties [1]. Some of these properties include extremely high thermal conductivity, extremely high optical polarizability, high structural perfection and exceptional properties of ballistic transport [2]. Different synthesis techniques like the arc discharge, laser vaporization and chemical vapor deposition methods have been used to grow carbon nano tubes. Among these methods, chemical vapor deposition (CVD) method, often called thermal-CVD, is being widely used to synthesize CNTs at large-scale. Transition metals such as Fe, Co and Ni are frequently used as catalysts. The selection and preparation of the substrate for CNT growth are important aspects which are deciding factors of the nanotubes yield and the ability to purify the product of the synthesis. Since the particle size of the metal catalyst has to be in the order of few nanometers for the growth of CNTs and MWCNTs, deposition of well separated metal nanopartic
Data Loading...
