Redox properties of birnessite from a defect perspective

作者：Haowei Peng, Ian G. McKendry, Ran Ding, Akila C. Thenuwara, Qing Kang, Samantha L. Shumlas, Daniel R. Strongin, Michael J. Zdilla, John P. Perdew · 发表于：Proceedings of the National Academy of Sciences · 年份：2017 · DOI：10.1073/pnas.1706836114 · 被引用次数：81 · 研究领域：Copper-based nanomaterials and applications、Catalytic Processes in Materials Science、Geochemistry and Elemental Analysis

layers, accompanied by interlayer charge-neutralizing cations. Using first-principles calculations, we reveal the nature of Mn(III) in birnessite with the concept of the small polaron, a special kind of point defect. Further taking into account the effect of the spatial distribution of Mn(III), we propose a theoretical model to explain the structure-performance dependence of birnessite as an oxygen evolution catalyst. We find an internal potential step which leads to the easy switching of the oxidation state between Mn(III) and Mn(IV) that is critical for enhancing the catalytic activity of birnessite. Finally, we conduct a series of comparative experiments which support our model.