Structural effects in electrocatalysis

The oxidation of ethylene glycol (EG) has been studied on platinum single-crystal surfaces in 0.1 M NaOH. A strong structural dependence of the reaction kinetics was found for all 12 single-crystal orientations investigated. The onset of the reaction occurs in the sequence Pt (110) > Pt (100) ≈ Pt (111). However, the peaks of the voltammetry curves for the low-index planes decrease in the order (111) > (110) > (100). Either the (111) or the (100) oriented steps cause a decrease in the activity of the (111) plane. Surfaces vicinal to the (100) plane exhibit a higher activity than Pt (100). The (111) oriented steps in the Pt (110) plane cause an increase in activity, while the (100) oriented steps decrease it. A parallelism between PtOH layer formation and the onset of the oxidation of EG was found which indicates that the reaction involves interaction of the adsorbed and dehydrogenated EG with Pt(OH) ads species.