Plate Paul, Höhn Christian, Bloeck Ulrike, Bogdanoff Peter, Fiechter Sebastian, Abdi Fatwa F, van de Krol Roel, Bronneberg Aafke C
Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, 10623 Berlin, Germany.
ACS Appl Mater Interfaces. 2021 Jan 20;13(2):2428-2436. doi: 10.1021/acsami.0c15977. Epub 2021 Jan 10.
There is an urgent need for cheap, stable, and abundant catalyst materials for photoelectrochemical water splitting. Manganese oxide is an interesting candidate as an oxygen evolution reaction (OER) catalyst, but the minimum thickness above which MnO thin films become OER-active has not yet been established. In this work, ultrathin (<10 nm) manganese oxide films are grown on silicon by atomic layer deposition to study the origin of OER activity under alkaline conditions. We found that MnO films thinner than 1.5 nm are not OER-active. X-ray photoelectron spectroscopy shows that this is due to electrostatic catalyst-support interactions that prevent the electrochemical oxidation of the manganese ions close to the interface with the support, while in thicker films, Mn and Mn oxide layers appear as OER-active catalysts after oxidation and electrochemical treatment. From our investigations, it can be concluded that one Mn-O monolayer is sufficient to establish oxygen evolution under alkaline conditions. The results of this study provide important new design criteria for ultrathin manganese oxide oxygen evolution catalysts.
迫切需要用于光电化学水分解的廉价、稳定且丰富的催化剂材料。氧化锰作为析氧反应（OER）催化剂是一个有趣的候选材料，但MnO薄膜成为OER活性的最小厚度尚未确定。在这项工作中，通过原子层沉积在硅上生长超薄（<10 nm）氧化锰薄膜，以研究碱性条件下OER活性的起源。我们发现厚度小于1.5 nm的MnO薄膜没有OER活性。X射线光电子能谱表明，这是由于静电催化剂-载体相互作用阻止了靠近与载体界面的锰离子的电化学氧化，而在较厚的薄膜中，Mn和Mn氧化物层在氧化和电化学处理后表现为OER活性催化剂。从我们的研究中可以得出结论，一个Mn-O单分子层足以在碱性条件下实现析氧。这项研究的结果为超薄氧化锰析氧催化剂提供了重要的新设计标准。
