Development of Ultrahigh Surface Area Porous Electrodes using Simultaneous and Sequential Meso- and Micro-structuring Me
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1127-T04-08
Development of Ultrahigh Surface Area Porous Electrodes using Simultaneous and Sequential Meso- and Micro-structuring Methods Franchessa Maddox1, Catherine Cook1,2, Leigh McKenzie1,2, Brenda O'Neil1,2, Elizabeth A. Junkin1, Christopher Redden1,2, Soumen Basu1, Martin G. Bakker1,2, Jan-Henrik Småtts3 and Mika Lindén3 1 Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, AL 354870336, U.S.A. 2 Center for Materials for Information Technology, The University of Alabama, Box 870209 Tuscaloosa, AL 35487-0209, U.S.A. 3 Department of Physical Chemistry, Åbo Akademi University, Turku, Finland ABSTRACT Very high surface area nanostructured metal electrodes are of interest as efficient current collectors. For thin film devices, the nanostructured metal can be grown in place using electrodeposition or electroless deposition. For larger devices metal electrodes structured at more than one length scale are desirable. Self-assembling surfactant templates are a versatile method of generating a range of nanostructures. As we report here, electrodeposition of nickel, cobalt and copper from liquid crystalline solutions of Triton X-100 produces a number of nanostructures, with significant surface area increases. Electrodeposition into templates with microstructure has proven more demanding. Oil-in-water Microemulsions of Tween surfactants and soy oil, produce micrometer scale structures, however measured nickel surface area does not scale with sample thickness. The method is also not robust, and was found to give microstructures only for nickel and cobalt. Experiments show that under our conditions a combination of nickel metal, nickel acetate and nickel/detergent microstructures are formed. INTRODUCTION There are many applications for high surface area porous metal electrodes in catalysis, electrolysis and batteries among other applications. Considerable work has been reported on methods of producing high surface area metal nanostructures as thin films on planar electrodes[1-6]. We have previously reported on the application of such methods[7] as well as other new methods[8] to 3-dimensional surfaces. Many of the nanostructure methods involve the use of self-assembling templates, either directly, or by using self-assembly to generate a hard template, which can be used to control the growth of the metal. As we have previously reported[8], and as we will note further in this report, not all such methods transition well from planar surfaces to the heterogenous and curved surfaces of typical three dimensional electrodes. Not all the various nanostructures are equally desirable for use in fabricating porous electrodes, particularly not for electrodes of macroscopic size. For liquid crystal[1-3], reverse micelle[6] and other self-assembling electrodeposition routes[4] the rate of film formation is slow so that only film thicknesses of a micron or less can be grown in a day. Cost effective fabrication of high surface area electrodes therefore needs efficient methods of generating micrometer scale metal st
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