科研之友
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摘要
Studies on the formation and reduction of surface oxide on Pt-Cu/C core-shell electrocatalysts have been carried out with reference to the nature and type of the adsorbed intermediates formed on the surface as a function of applied potential. In-situ measurements were made using EQCM coupled with cyclic voltammetry to monitor the surface changes. Comparisons between the novel %26quot;core-shell%26quot; electrocatalysts, conventional Pt/C electrocatalysts and unsupported Pt black electrocatalysts have been made. We find that interfacial mass of the adsorbed species increases in a continuous linear manner as the potential is increased during the anodic oxidation. We also find evidence to suggest that the oxide formation on the core-shell electrocatalyst occurs via the formation of adsorbed hydroxyl species involving one electron per surface site and that on pure Pt proceeds via adsorbed oxide involving two electrons per site. A different mechanism for oxide growth on these catalysts was confirmed by the change in the Tafel slopes for anodic oxidation of the surface. The results showed that the core-shell catalyst surface is less oxidized and that the surface strain imposes a barrier to surface oxidation. This also explains the shift in the oxide stripping peak that has been observed for the Pt binary alloy catalysts.
- 出版日期2012
