Platinum electrodes faceted surfaces

This result is consistent with the observed effective poisoning of the CO oxidation reaction as reflected in the increased potential induced by bismuth in the cyclic voltammetry on the supported platinum electrodes (Figure 10a). The voltammetry of CO stripping on the supported catalysts indicates a similar behavior to that found on Pt(llO) in that bismuth results in a higher overpotential for CO oxidation. One must conclude that the morphology of the supported platinum catalyst results in facets more akin to the more open-packed Pt(l 10) surface than the Pt(lll) surface, a conclusion supported by comparison of the bismuth redox chemistry on the supported catalyst and the single-crystal surfaces [77]. 

The major effort in HOR electro-catalysis has been focused on understanding the rate dependency on the atomic-scale morphology of a platinum single-crystal surface. Recently, catalysis studies on well-defined Pt single-crystal electrodes clearly demonstrated that the delivered current during the HOR on Pt (hkl) varies with the crystal face symmetry, i.e., it is a structure sensitivity reaction (Markovic, 2003 Markovic etal., 2002). The facets of a well formed crystal, or internal planes through a crystal structure, or a lattice, are specified in terms of miller indices, h, k and 1. These indices (hkl) represent the set of all parallel planes. 

Lang and Clavilier studied the influence of the crystalline surface structure of platinum on the electrochemical polymerization of 3-methylthiophene [63]. The superficial crystalline structure greatly influenced the location of the polymer film on a polyoriented electrode surface. At a low polymerization potential, the (111) facets were first covered with polymer film. The... 

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