den Dunnen Angela, van der Niet Maria J T C, Badan Cansin, Koper Marc T M, Juurlink Ludo B F
Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Phys Chem Chem Phys. 2015 Apr 7;17(13):8530-7. doi: 10.1039/c4cp03165b. Epub 2014 Sep 30.
We have examined water desorption from Pt(111) terraces of varying width and its dependence on precoverage by deuterium (D) with temperature programmed desorption studies. We observe distinct water desorption from (100) steps and (111) terraces, with steps providing adsorption sites with a higher binding energy than terraces. Preadsorption of D at the steps causes annihilation of water stabilization at the steps, while it also causes an initial stabilization of water on the (111) terraces. When the (111) terraces also become precovered with D, this water stabilization trend reverses on all surfaces. Destabilization continues for stepped surfaces containing up to 8-atom wide (111) terraces with a (100) step type and these become hydrophobic, in contrast to surfaces with a (110) step type and with the infinite (111) terrace. Our results illustrate how surface defects and a delicate balance between intermolecular forces and the adsorption energy govern hydrophobic vs. hydrophilic behavior, and that the influence of steps on the adsorption of water on nano-structured platinum surfaces has a very long-ranged character.
我们通过程序升温脱附研究，考察了不同宽度的Pt(111)平台上的水脱附情况及其对氘（D）预覆盖度的依赖性。我们观察到(100)台阶和(111)平台上有明显的水脱附现象，台阶提供的吸附位点比平台具有更高的结合能。在台阶处预吸附D会导致台阶处水的稳定作用消失，同时也会使(111)平台上的水初步稳定。当(111)平台也被D预覆盖时，这种水的稳定趋势在所有表面上都会逆转。对于含有高达8个原子宽的(111)平台且具有(100)台阶类型的台阶表面，失稳现象会持续，这些表面会变得疏水，这与具有(110)台阶类型和无限(111)平台的表面形成对比。我们的结果说明了表面缺陷以及分子间力与吸附能之间的微妙平衡如何决定疏水与亲水行为，并且台阶对纳米结构铂表面上水吸附的影响具有非常长程的特性。
