The corrosion of materials is an undesirable and costly process affecting many areas of technology and everyday life. As such, considerable effort has gone into understanding and preventing it. Organic molecule based coatings can in certain circumstances act as effective corrosion inhibitors. Although they have been used to great effect for more than sixty years, how they function at the atomic-level is still a matter of debate. In this work, computer simulation approaches based on density functional theory are used to investigate benzotriazole (BTAH), one of the most widely used and studied corrosion inhibitors for copper. In particular, the structures formed by protonated and deprotonated BTAH molecules on Cu(111) have been determined and linked to their inhibiting properties. It is found that hydrogen bonding, van der Waals interactions and steric repulsions all contribute in shaping how BTAH molecules adsorb, with flat-lying structures preferred at low coverage and upright configurations preferred at high coverage. The interaction of the dehydrogenated benzotriazole molecule (BTA) with the copper surface is instead dominated by strong chemisorption via the azole moiety with the aid of copper adatoms. Structures of dimers or chains are found to be the most stable structures at all coverages, in good agreement with scanning tunnelling microscopy results. Benzotriazole thus shows a complex phase behaviour in which van der Waals forces play an important role and which depends on coverage and on its protonation state and all of these factors feasibly contribute to its effectiveness as a corrosion inhibitor.

中文翻译：

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了解范德华DFT方法的腐蚀抑制作用：苯并三唑。

材料的腐蚀是不希望的且成本高昂的过程，会影响技术和日常生活的许多领域。因此，在理解和预防上已经付出了很大的努力。基于有机分子的涂料在某些情况下可以充当有效的腐蚀抑制剂。尽管它们已经被广泛使用了60多年，但它们在原子级上如何发挥作用仍是一个有争议的问题。在这项工作中，基于密度泛函理论的计算机模拟方法被用于研究苯并三唑（BTAH），苯并三唑是最广泛使用和研究的铜腐蚀抑制剂之一。特别是，已确定了由质子化和去质子化的BTAH分子在Cu（111）上形成的结构，并将其与它们的抑制性能相关联。发现氢键 范德华相互作用和空间斥力都有助于塑造BTAH分子的吸附方式，低覆盖度时优选平坦结构，高覆盖率时优选直立构型。脱氢的苯并三唑分子（BTA）与铜表面的相互作用取而代之的是借助借助于铜原子的经由唑部分的强化学吸附作用。发现二聚体或链的结构在所有覆盖范围内都是最稳定的结构，与扫描隧道显微镜的结果非常吻合。因此，苯并三唑显示出复杂的相行为，其中范德华力起着重要的作用，并且取决于覆盖率及其质子化状态，所有这些因素都切实地有助于其作为缓蚀剂的有效性。