270737 Catalyst-Support Interactions and Their Influence in Water-Assisted Carbon Nanotube Carpet Growth

Tuesday, October 30, 2012: 9:10 AM
311 (Convention Center )
Placidus B. Amama1, Cary L. Pint2, Francesca Mirri3, Matteo Pasquali4, Robert H. Hauge2 and Benji Maruyama5, (1)Materials & Manufacturing Directorate, RXBT, Air Force Research Laboratory/UDRI, WPAFB, OH, (2)Richard E. Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, TX, (3)Department of Chemical & Biomolecular Engineering, Rice University, Houston, TX, (4)Chemical and Biomolecular Engineering, Rice University, Houston, TX, (5)Materials & Manufacturing Directorate, RXBN, Wright Patterson Air Force Research Laboratory, Dayton, OH

The growth and catalyst morphological changes occurring for thin Fe layers deposited on Al2O3, MgO, TiN, and ZrO2 using water-assisted chemical vapor deposition are compared. The growth behaviors of the catalyst substrates were evidently different, with Al2O3/Fe supporting high-quality carbon nanotube (CNT) carpet growth and showing the highest activity and longest lifetime. The TiN/Fe catalyst also supported CNT carpet growth, albeit with much lower activity, shorter lifetime, and lower CNT quality while MgO/Fe and ZrO2/Fe did not support CNT carpet growth under standard growth conditions. Studies using a combination of atomic force microscopy and X-ray photoelectron spectroscopy revealed a general correlation between the catalyst behavior (activity and lifetime) and the evolution of the catalyst (Ostwald ripening and subsurface diffusion rates).  Analysis of MgO/Fe and ZrO2/Fe catalyst systems raise interesting questions related to additional chemical interactions between the substrate and catalyst that could influence nucleation and CNT growth. This work provides a step toward understanding the challenges that arise in engineering efficient CNT growth processes on a desired substrate.

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