Cola, Baratunde A.

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    Highly specular carbon nanotube absorbers
    (Georgia Institute of Technology, 2010-10) Wang, X. J. ; Wang, L. P. ; Adewuyi, O. S. ; Cola, Baratunde A. ; Zhang, Zhuomin ; Georgia Institute of Technology. Center for Organic Photonics and Electronics ; Georgia Institute of Technology. School of Mechanical Engineering
    Specular black materials have important applications, such as in absolute cryogenic radiometers, space-borne spectroradiometers, and some energy conversion devices. While vertically aligned carbon nanotubes (VACNT) can have close-to-unity absorptance, so far the reported reflection has been essentially diffuse. This letter describes a highly specular black absorber made of VACNT. Both the bidirectional reflectance distribution function and specular reflectance were measured at the wavelength λ = 635 nm using a laser scatterometer. The ordinary and extraordinary optical constants were obtained by fitting the specular reflectance, calculated from modified reflectance formulae for light incident from air to a uniaxial medium, considering surface roughness. Furthermore, the absorptance at λ = 635 nm was shown to be 0.994±0.002, based on the measured directional-hemispherical reflectance.
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    Nitrogen- and Boron-Doped Carbon Nanotube Electrodes in a Thermo-Electrochemical Cell
    (Georgia Institute of Technology, 2012) Salazar, Pablo F. ; Kumar, Satish ; Cola, Baratunde A. ; Georgia Institute of Technology. Center for Organic Photonics and Electronics
    We explore the prospects of using doped carbon nanotube (CNT) electrodes to increase the output power of thermo-electrochemical cells (TECs). CNT buckypaper electrodes doped with nitrogen and boron were characterized using cyclic voltammetry, impedance spectroscopy, and TEC test with potassium ferri/ferrocyanide electrolyte. Both doping states increased the electrochemically active surface area of CNT electrodes. Electrostatic interactions with potassium ions altered the charge transfer kinetics for doped CNT electrodes; yet, the symmetry of the charge transfer remained approximately equal to that of pristine CNTs. In TEC test, accumulation of potassium ions at doped CNT electrodes was found to reduce short-circuit current.
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    Conformally coating vertically aligned carbon nanotube arrays using thermal decomposition of iron pentacarbonyl
    (Georgia Institute of Technology, 2012-05) Hildreth, Owen ; Cola, Baratunde A. ; Graham, Samuel ; Wong, C. P. ; Georgia Institute of Technology. Center for Organic Photonics and Electronics
    Conformally coating vertically aligned carbon nanotubes (v-CNT) with metals or oxides can be difficult because standard line-of-sight deposition methods, such as dc sputter coating and electron-beam evaporation, are hindered by the low mean-free-path with
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    Photo-thermal enhanced carbon nanotube rectenna arrays for solar energy conversion
    (Georgia Institute of Technology, 2012-09) Cola, Baratunde A. ; Sibble, Dan ; Georgia Institute of Technology. Office of Sponsored Programs ; Georgia Institute of Technology. School of Mechanical Engineering
    This project was aimed at fabricating dense ordered arrays of vertical carbon nanotube (CNT) rectenna with diode components exhibiting high asymmetry and nonlinearity. Its broad objectives were to explore and demonstrate the devices with solar energy conversion at high solar frequencies and with efficient power conversion that can be used in a variety of defense applications.