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Abstract
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The formation of platinum nucleus on the freshly polished aluminum (Al) and anodized
aluminum electrodes (Al2O3/Al) was studied by cyclic voltammetry. Results showed that
the deposition of platinum on freshly polished aluminum from an aqueous 0.5M
phosphate buffer solution containing H2PtCl6 takes place rapidly through the electroreduction
of dissolved Pt (IV) ions. At shorter deposition times, small particles of platinum
crystals were formed on the aluminum and the surface coverage was imperfect. At longer
deposition times, the size of the platinum crystals increases while their number decreases
due to the coalescence and agglomeration processes. The electrodeposition of Pt on the Al
electrode was conveniently carried out over the Al2O3/Al electrode. The electrochemical
and catalytic activities of the Pt/Al and Pt/Al2O3/Al electrodes were studied in 0.1M H2SO4
solution. In cyclic voltammetry, the two pair symmetric peaks appeared in 0.1M H2SO4
solution which was attributed to the formation of strongly (Hs) and weakly bounded
hydrogen (Hw). The occurrence of the third anodic hydrogen peak (H3rd) was revealed at low
scan rate and in high concentration of H2SO4. At potentials more negative than 0.3V vs.
SCE, the current is mainly due to hydrogen evolution reaction. The influence of the various
parameters such as deposition method and amount of platinum, sulfuric acid concentration
and medium temperature on the hydrogen evolution reaction is described. Finally the
kinetic of the hydrogen evolution reaction is also discussed on the Pt/Al electrode.
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