Department of Applied Physics, Chalmers University of Technology, Gothenburg, 412 96, Sweden.
Phys Chem Chem Phys. 2013 Dec 21;15(47):20456-62. doi: 10.1039/c3cp52554f. Epub 2013 Sep 10.
Water interaction with nanostructured graphite surfaces is strongly dependent on the surface morphology. In this work, temperature programmed desorption (TPD) in combination with quadrupole mass spectrometry (QMS) has been used to study water ice desorption from a nanostructured graphite surface. This model surface was fabricated by hole-mask colloidal lithography (HCL) along with oxygen plasma etching and consists of a rough carbon surface covered by well defined structures of highly oriented pyrolytic graphite (HOPG). The results are compared with those from pristine HOPG and a rough (oxygen plasma etched) carbon surface without graphite nanostructures. The samples were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TPD experiments were conducted for H2O coverages obtained after exposures between 0.2 and 55 langmuir (L) and reveal a complex desorption behaviour. The spectra from the nanostructured surface show additional, coverage dependent desorption peaks. They are assigned to water bound in two-dimensional (2D) and three-dimensional (3D) hydrogen-bonded networks, defect-bound water, and to water intercalated into the graphite structures. The intercalation is more pronounced for the nanostructured graphite surface in comparison to HOPG surfaces because of a higher concentration of intersheet openings. From the TPD spectra, the desorption energies for water bound in 2D and 3D (multilayer) networks were determined to be 0.32 ± 0.06 and 0.41 ± 0.03 eV per molecule, respectively. An upper limit for the desorption energy for defect-bound water was estimated to be 1 eV per molecule.
水与纳米结构石墨表面的相互作用强烈依赖于表面形态。在这项工作中，我们使用程序升温脱附（TPD）结合四极质谱（QMS）研究了水冰从纳米结构石墨表面的脱附。该模型表面是通过孔掩模板胶体光刻（HCL）结合氧等离子体刻蚀制备的，由粗糙的碳表面组成，表面覆盖有高度取向热解石墨（HOPG）的定义良好的结构。结果与原始 HOPG 和无石墨纳米结构的粗糙（氧等离子体刻蚀）碳表面进行了比较。使用扫描电子显微镜（SEM）和原子力显微镜（AFM）对样品进行了表征。TPD 实验是在暴露于 0.2 至 55 毫巴（L）之间获得的 H2O 覆盖物后进行的，揭示了复杂的脱附行为。来自纳米结构表面的光谱显示出额外的、依赖于覆盖度的脱附峰。它们被分配到二维（2D）和三维（3D）氢键网络中结合的水、缺陷结合的水和嵌入石墨结构中的水。与 HOPG 表面相比，由于层间开口的浓度更高，纳米结构石墨表面的插层更为明显。从 TPD 光谱中，确定了二维（2D）和 3D（多层）网络中结合水的脱附能分别为 0.32±0.06 和 0.41±0.03 eV/分子。缺陷结合水的脱附能上限估计为 1 eV/分子。
