Electrochemistry of Pt (100) in alkaline media: A voltammetric study

Pt (100) is one of the fcc metal surface planes that reconstruct upon annealing at high temperatures. The state of the surface is important in electrochemistry, in order to correlate catalytic behavior with surface structure. Therefore, the behavior of single crystalline Pt (100) in alkaline media was investigated, with particular attention paid to surface long-range order. It was found that, in line with previous results, the manner of cooling the crystal after annealing influenced the state of surface significantly, with a profound effect on blank cyclic voltammetry as well as on carbon monoxide oxidation. Different ratios of inert and reductive gases were used to see if an optimal mixture could be obtained. Using air, argon, hydrogen, CO, and combinations of these gases gave rise to different states of the surface, with clear observable differences in blank voltammetric behavior and CO stripping. Also, the effect of alkali-metal cations and bromide on the blank and CO stripping voltammetry was investigated. Our main conclusion is that cooling in a carbon monoxide containing gas gives a clean, almost defect-free surface with long-range 1 × 1 symmetry. A similar surface can also be prepared with a hydrogen-containing cooling gas, but the content of hydrogen in that stream is critical.