Department of Chemistry and Pharmacy, Chemistry of Thin Film Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 4, 91058, Erlangen, Germany.
Department für Geographie und Geowissenschaften, GeoZentrum NordBayern, Applied Geology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 5, 91054, Erlangen, Germany.
Nat Commun. 2018 Nov 1;9(1):4565. doi: 10.1038/s41467-018-07031-1.
Understanding the mechanism of water oxidation to dioxygen represents the bottleneck towards the design of efficient energy storage schemes based on water splitting. The investigation of kinetic isotope effects has long been established for mechanistic studies of various such reactions. However, so far natural isotope abundance determination of O produced at solid electrode surfaces has not been applied. Here, we demonstrate that such measurements are possible. Moreover, they are experimentally simple and sufficiently accurate to observe significant effects. Our measured kinetic isotope effects depend strongly on the electrode material and on the applied electrode potential. They suggest that in the case of iron oxide as the electrode material, the oxygen evolution reaction occurs via a rate-determining O-O bond formation via nucleophilic water attack on a ferryl unit.
了解水氧化为氧气的机制是设计基于水分解的高效储能方案的瓶颈。动力学同位素效应的研究长期以来一直是各种此类反应的机理研究的基础。然而，到目前为止，还没有应用于确定固体电极表面产生的 O 的天然同位素丰度的方法。在这里，我们证明了这样的测量是可行的。此外，它们在实验上简单且足够准确，可以观察到显著的效果。我们测量的动力学同位素效应强烈依赖于电极材料和所施加的电极电势。它们表明，在氧化铁作为电极材料的情况下，氧气析出反应是通过亲核水分子攻击铁氧单元来形成决定速率的 O-O 键来进行的。
