Durability and surface chemistry of horizontally aligned CNT films as electrodes upon electrolysis of acidic aqueous solution
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We devised a simple and effective method of electrochemical functionalization of horizontally aligned CNT films in diluted HCl and H2SO4 solutions upon their electrolysis under a constant current mode. We were able to cause notable generation of carbon–oxygen and carbon–chlorine functional groups on the CNT film anodes as proven by EDX, XPS, and Raman spectroscopy. As a consequence, we observed significant changes of the morphology of the material under electron microscopy, what translated into improved compatibility of CNTs with hydrophilic media. In turn, application of CNT films as cathodes was found as a powerful tool for a thorough cleaning of the nanotubes. Finally, we demonstrated that by the selection of appropriate conditions, CNT films can act as easy-to-make and flexible electrodes with a high stability and performance superior to graphite for generation of non-oxidizing gases such as hydrogen from solution. CNT film electrodes are two orders of magnitude lighter and require much lower overpotential for faradaic splitting of water.
KeywordsWater Contact Angle Hydrochloric Acid Solution Lower Overpotential Constant Current Mode Hemispherical Electron Analyzer
D.J. and K.K. acknowledge the European Research Council (under the Seventh Framework Program FP7/2007–2013, ERC Grant Agreement No 259061) and the Royal Society for the financial support. S.B. is greatly indebted to the Foundation for Polish Science in the framework of KOLUMB Program (FNP-DS-402–7410/2012/Kf), Ministry of Science and Higher Education in Poland (IP2012 003572) in the framework of IUVENTUS PLUS Program and National Science Centre in Poland in the framework of SONATA (2012/05/D/ST5/03519) for financing the research. X-ray photoelectron spectra were obtained at the National EPSRC XPS User’s Service (NEXUS) at Newcastle University, an EPSRC Mid-Range Facility.
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