Diaz-Morales Oscar, Hersbach Thomas J P, Badan Cansin, Garcia Amanda C, Koper Marc T M
Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands.
Faraday Discuss. 2018 Oct 1;210(0):301-315. doi: 10.1039/c8fd00062j.
The "hydrogen region" of platinum is a powerful tool to structurally characterize nanostructured platinum electrodes. In recent years, the understanding of this hydrogen region has improved considerably: on Pt(111) sites, there is indeed only hydrogen adsorption, while on step sites, the hydrogen region involves the replacement of adsorbed hydrogen by adsorbed hydroxyl which interacts with co-adsorbed cations. However, the hydrogen region features an enigmatic and less well-understood "third hydrogen peak", which develops on oxidatively roughened platinum electrodes as well as on platinum electrodes with a high (110) step density that have been subjected to a high concentration of hydrogen. In this paper, we present evidence that the peak involves surface-adsorbed hydrogen (instead of subsurface hydrogen) on a locally "reconstructed" (110)-type surface site. This site is unstable when the hydrogen is oxidatively removed. The cation sensitivity of the third hydrogen peak appears different from other step-related peaks, suggesting that the chemistry involved may still be subtly different from the other features in the hydrogen region.
铂的“氢区域”是对纳米结构铂电极进行结构表征的有力工具。近年来，对该氢区域的理解有了显著提高：在Pt(111)位点上，确实只有氢吸附，而在台阶位点上，氢区域涉及吸附的羟基取代吸附的氢，且羟基与共吸附的阳离子相互作用。然而，氢区域有一个神秘且了解较少的“第三氢峰”，它在氧化粗糙化的铂电极以及具有高(110)台阶密度且暴露于高浓度氢的铂电极上都会出现。在本文中，我们提供证据表明，该峰涉及局部“重构”的(110)型表面位点上的表面吸附氢（而非次表面氢）。当氢被氧化去除时，该位点不稳定。第三氢峰的阳离子敏感性似乎与其他与台阶相关的峰不同，这表明其中涉及的化学过程可能仍与氢区域的其他特征略有不同。
