Introducing surface defects on molybdenum disulfide (MoS₂) crystals plays a crucial role in enhancing the electrocatalytic activity toward the hydrogen evolution reaction (HER). Despite the remarkable progress in this area, the precise control of the size, distance, and defective areas with minimal surface contamination remains unachieved. Conventional microfabrication methods often leave organic residues on the surface that impair electrocatalytic activity and hinder interface elucidation by advanced characterization tools. In this study, we pattern for the first-time arrays of pillars in nanometer-thick MoS₂ flakes using a focused ion beam to enhance HER activity. We observe size-dependent stability of the edge-like defects under HER conditions with defective areas. The pillars undergo chemical and structural changes post-patterning due to an amorphization process, unambiguously confirmed by atomic force microscopy, Raman spectroscopy, and synchrotron X-ray photoelectron spectroscopy. Furthermore, the amorphization process is more pronounced in specific in-plane directions, as confirmed by transmission electron microscopy. The electrocatalytic activity of the pillars was measured using a recently reported fabrication method, allowing us to unequivocally correlate defects with HER activity. Microelectrodes with less pillars, i.e. less catalytic sites, demonstrate a lower overpotential of 349 mV at 10 mA cm⁻² showcasing a groundbreaking advancement in their fabrication.

中文翻译：

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聚焦离子束图案化的 MoS2 晶体中边缘状缺陷阵列的尺寸依赖性电催化析氢活性


在二硫化钼 （MoS₂） 晶体上引入表面缺陷在增强析氢反应 （HER） 的电催化活性方面起着至关重要的作用。尽管在这一领域取得了显著进展，但仍然无法以最小的表面污染精确控制大小、距离和缺陷区域。传统的微纳加工方法通常会在表面留下有机残留物，从而损害电催化活性并阻碍高级表征工具的界面解析。在这项研究中，我们使用聚焦离子束首次在纳米厚的 MoS₂ 薄片中对柱阵列进行图案化，以增强 HER 活性。我们在 HER 条件下观察到有缺陷区域的边缘状缺陷的尺寸依赖性稳定性。由于非晶化过程，柱子在图案化后发生化学和结构变化，原子力显微镜、拉曼光谱和同步加速器 X 射线光电子能谱明确证实了这一点。此外，透射电子显微镜证实，非晶化过程在特定的平面内方向上更为明显。使用最近报道的制造方法测量了柱子的电催化活性，使我们能够明确地将缺陷与 HER 活性相关联。具有较少支柱的微电极，即较少的催化位点，在 10 mA ^cm-2 时表现出 349 mV 的较低过电位，展示了其制造的突破性进展。