Davis Earl Matthew, Bergmann Arno, Zhan Chao, Kuhlenbeck Helmut, Cuenya Beatriz Roldan
Department of Interface Science, Fritz-Haber Institute of the Max Planck Society, 14195, Berlin, Germany.
Nat Commun. 2023 Aug 8;14(1):4791. doi: 10.1038/s41467-023-40461-0.
Water electrolysis to produce 'green H' with renewable energy is a promising option for the upcoming green economy. However, the slow and complex oxygen evolution reaction at the anode limits the efficiency. CoO with added iron is a capable catalyst for this reaction, but the role of iron is presently unclear. To investigate this topic, we compare epitaxial CoO(111), CoFeO(111), and FeO(111) thin film model electrocatalysts, combining quasi in-situ preparation and characterization in ultra-high vacuum with electrochemistry experiments. The well-defined composition and structure of the thin epitaxial films permits the obtention of quantitatively comparable results. CoFeO(111) is found to be up to about four times more active than CoO(111) and about nine times more than FeO(111), with the activity depending acutely on the Co/Fe concentration ratio. Under reaction conditions, all three oxides are covered by oxyhydroxide. For CoFeO(111), the oxyhydroxide's Fe/Co concentration ratio is stabilized by partial iron dissolution.
利用可再生能源通过水电解生产“绿色氢气”是即将到来的绿色经济的一个有前景的选择。然而，阳极处缓慢且复杂的析氧反应限制了效率。添加铁的氧化钴是该反应的一种有效催化剂，但目前铁的作用尚不清楚。为了研究这个课题，我们将超高真空中的准原位制备和表征与电化学实验相结合，比较了外延CoO(111)、CoFeO(111)和FeO(111)薄膜模型电催化剂。外延薄膜明确的组成和结构使得能够获得定量可比的结果。发现CoFeO(111)的活性比CoO(111)高约四倍，比FeO(111)高约九倍，活性强烈依赖于Co/Fe浓度比。在反应条件下，所有三种氧化物都被羟基氧化物覆盖。对于CoFeO(111)，羟基氧化物的Fe/Co浓度比通过部分铁溶解而稳定。
