Structural, electronic and chemical properties of low-index high-entropy alloy surfaces

讨论了高熵合金在腐蚀和磨损防护以及电催化剂等领域的应用。尽管HEAs的表面性质在这些应用中起着核心作用，但它们在很大程度上仍未被探索。本文详细研究了高熵CoCrFeNi合金的低指数(100)、(110)和(111)表面的性质。采用了磁控溅射在单晶衬底上制备的优化外延层。用低能电子衍射、低能电子显微镜和扫描探针显微镜对其表面结构进行了表征。用X射线光电子能谱测定了表面的化学成分。用角度分辨光电子能谱阐明了可能发生的电子表面态的色散。除了各种低指数表面的物理性质外，还将确定它们对氧气和水的吸附行为。此外，这些表面将用于电化学研究。特别是对不同取向的催化剂在析氢反应中的催化性能进行了比较。

High-entropy alloys (HEAs) are discussed for applications in the fields of corrosion and wear protection as well as electrocatalysts. Although the surface properties of HEAs play a central role in these applications, they are still largely unexplored. In this project, the properties of low-index (100), (110) and (111) surfaces of the high entropy alloy CoCrFeNi are investigated in detail. Optimized epitaxial layers are used, which are produced by magnetron sputtering on single-crystalline substrates. The surface structures are characterized by low energy electron diffraction, low energy electron microscopy and scanning probe microscopy. The chemical composition of the surfaces is determined by X-ray photoelectron spectroscopy. The dispersion of electronic surfaces states that may occur is elucidated using angle-resolved photo-electron spectroscopy. In addition to the physical properties of the various low-index surfaces, their adsorption behavior with respect to oxygen and water will also be determined. Furthermore, the surfaces will be used in electrochemical studies. In particular, the different orientations will be compared with respect to their catalytic properties in the hydrogen evolution reaction.