Electrochemical behaviour of single walled carbon nanotubes – Hydrogen storage and hydrogen evolution reaction

P. S. FERNANDEZ; E. B. CASTRO; S. G. REAL; M. E. MARTINS

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2009 vol. 34 p. 8115 - 8126

0360-3199

The electrochemical behaviour of single walled carbon nanotubes (SWCNT) related to themechanism involved in the hydrogen electrode reaction applying electrochemical andspectroscopic techniques is studied. Cyclic voltammetry applied to electrodes containingdifferent percentages of SWCNT demonstrates that this material can behave as efficientcapacitor and that the hydrogen electrode reaction develops through the H-electrosorptionfollowed by the formation of molecular H2 and its evolution. Also, SWCNT are able tostorage hydrogen within their porous structure. This is confirmed through the galvanostaticcharge and discharge experiments. Electrochemical impedance spectroscopyallowed calculating the real area that takes part in the electrode reaction and the main andvaluable conclusion is that the hydrogen electrode reaction consists of a simple chargetransfer reaction and that the H adatom relaxation or diffusion processes can be disregarded.Furthermore, a model proposed for their structure which was validated throughimpedance experiments confirms those conclusions. Results of Raman spectra allowedidentifying the nature of the electrodes confirming that after purification the material iscomposed of single walled carbon nanotubes.