Growth of Carbon Nanotubes on Mesoporous Silica Coated Planar and Three-Dimensional Surfaces
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Growth of Carbon Nanotubes on Mesoporous Silica Coated Planar and Three-Dimensional Surfaces Katrina Staggemeier1, Jin Ke2, Alison Downard2, Vladimir Golovko2, Nitin Chopra3, Martin G. Bakker1 1 Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336 2 Department of Chemistry, University of Canterbury, Canterbury, Christchurch, New Zealand 3 Department of Materials and Metallurgical Engineering, The University of Alabama, Tuscaloosa. ABSTRACT Well ordered arrays of carbon nanotubes (CNTs) are of interest for a broad range of potential applications including energy storage and as catalyst supports. On some substrates such as copper and nickel, CNTs do not grow well or at all. We have previously shown that mesoporous silica thin films can be deposited onto metal substrates including copper and nickel, and that, after removal of the templating surfactant, the mesoporous silica film can be used as template for the electrodeposition of metals to give metal nanostructures.[Campbell et. al., Micro. Meso. Mater., 97, 114-121 (2006)] The size of the metal nanostructures makes them attractive as seeds for growth of CNTs. We have found that under appropriate conditions nickel deposited into mesoporous silica can act as catalyst for CNT growth on a number of different substrates including copper coated silicon wafers, and nickel foam. Using three different furnaces and different feed streams it was found that the growth is sensitive to carbon source; acetylene and ethylene both produced CNTs whereas attempts to produce CNTs using xylene have so far been unsuccessful. Well ordered mesoporous silica thin films could potentially give arrays of nanorod seeds, leading to well ordered arrays of CNTs, SEM images of some of our samples show dense CNT arrays, but do not indicate significant ordering. INTRODUCTION Well ordered arrays of carbon nanotubes (CNTs) are of interest for a broad range of potential applications including energy storage and as catalyst supports. On some substrates such as copper and nickel, CNTs do not grow well or at all. For fundamental catalysis studies it was desired to grow well ordered arrays of single walled carbon nanotubes. For energy storage applications it is desirable to grow the CNTs on a three dimensionally porous conductor (to allow for efficient electron transport and high energy density). Nickel foam is a readily available commercial material, that is used as current collector in batteries and that is a popular substrate for super capacitor research. There have previously been reports1,2 of growth of carbon nanofibers on nickel foam, but we are not of aware of methods that produce carbon nanotubes. There has been considerable interest in using the templating properties of mesoporous silica to produce, small 2-5 nm, diameter nanoparticles suitable for catalyzing the growth of single walled carbon nanotubes.3-8 The catalyst particles are formed in the mesoporous silica by a variety of methods including electrodeposition.9 As we are interested in growing carbon nanotubes on
