Evazzade Iman, Zagalskaya Alexandra, Alexandrov Vitaly
Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.
Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.
J Phys Chem Lett. 2022 Apr 7;13(13):3047-3052. doi: 10.1021/acs.jpclett.1c04187. Epub 2022 Mar 30.
Cathodic corrosion of metals discovered more than 120 years ago remains a poorly understood electrochemical process. It is believed that the corrosion intermediates formed during cathodic polarization are extremely short-lived species because of their high reactivity. Together with the concurrent vigorous hydrogen evolution, this makes it challenging to investigate the reaction mechanism and detect the intermediates experimentally. From a computational standpoint, the process also presents a serious challenge as it occurs at rather low negative potentials in concentrated alkaline solutions. Here, we use density-functional-theory calculations to elucidate the identity of reaction intermediates and their reactivity at the Pt(111)/electrolyte interface. By controlling the electrode potential in an experimentally relevant region through constant Fermi-level molecular dynamics, we reveal the formation of alkali cation-stabilized Pt hydrides as intermediates of cathodic corrosion. The results also suggest that the found Pt anions could discharge at the interface to produce H by reacting with either surface-bound hydrogen species or solution water molecules.
120多年前发现的金属阴极腐蚀仍是一个人们了解甚少的电化学过程。据信，阴极极化过程中形成的腐蚀中间体是寿命极短的物种，因为它们具有高反应活性。再加上同时发生的剧烈析氢反应，这使得研究反应机理并通过实验检测中间体具有挑战性。从计算的角度来看，该过程也带来了严峻挑战，因为它发生在浓碱性溶液中相当低的负电位下。在此，我们使用密度泛函理论计算来阐明反应中间体的身份及其在Pt(111)/电解质界面的反应活性。通过恒费米能级分子动力学在实验相关区域控制电极电位，我们揭示了碱金属阳离子稳定的铂氢化物作为阴极腐蚀中间体的形成。结果还表明，所发现的铂阴离子可在界面放电，通过与表面结合的氢物种或溶液水分子反应生成氢气。
