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Ordering and Phase Control in Epitaxial Double-Perovskite Catalysts for the Oxygen Evolution Reaction
ACS Catalysis ( IF 11.3 ) Pub Date : 2017-09-20 00:00:00 , DOI: 10.1021/acscatal.7b02036
Felix Gunkel 1 , Lei Jin 2, 3 , David N. Mueller 3 , Clemens Hausner 1 , Daniel S. Bick 1 , Chun-Lin Jia 2, 3 , Theodor Schneller 1 , Ilia Valov 3 , Rainer Waser 1, 3 , Regina Dittmann 3
Affiliation  

The complex oxide compound praseodymium barium cobalt oxide (PBCO) is an efficient catalyst for the oxygen evolution reaction (OER) during electrochemical water splitting, with an activity that is mainly ascribed to PBCO’s inherent atomic structure and band alignment. Here, we report on epitaxial PBCO thin films showing electrocatalytic properties, with current densities of up to 10 mA/cm2 at 1.8 V vs RHE. Dense PBCO thin films are synthesized in a disordered perovskite phase as well as in a coherently oxygen vacancy ordered (double) perovskite phase, in which oxygen vacancies are incorporated in every second CoO2−δ atomic plane along the out-of-plane direction. The transition from disordered to ordered growth occurs with temperature control during the growth process and can be directly monitored in situ by means of reflection high-energy electron diffraction. The epitaxial fabrication process allows the control of the structure and phase of the oxide catalysts, providing model systems for exploring structure–property relations and atomistic processes of catalysis during the OER. For all structural compositions, we demonstrate remarkably similar catalytic properties, indicating a negligible effect of the structural bulk phase on OER catalysis. Rational design routes for perovskite catalysts derived merely from bulk properties should therefore be met with suspicion.

中文翻译:

外延双钙钛矿催化剂中析氧反应的有序化和相控制

复合氧化物compound钴酸钴钡(PBCO)是电化学水分解过程中氧气释放反应(OER)的有效催化剂,其活性主要归因于PBCO固有的原子结构和能带排列。在这里,我们报道了具有电催化特性的外延PBCO薄膜,在1.8 V vs. RHE的电流密度下,其电流密度高达10 mA / cm 2。致密的PBCO薄膜是在无序的钙钛矿相以及相干的氧空缺有序(双)钙钛矿相中合成的,其中氧空位每第二个CoO2 被掺入沿平面外方向的原子平面。从无序生长到有序生长的转变发生在生长过程中的温度控制下,并且可以通过反射高能电子衍射直接进行原位监测。外延制造过程允许控制氧化物催化剂的结构和相,从而提供了模型系统,用于探索OER期间的结构-性质关系和催化的原子过程。对于所有结构组成,我们表现出非常相似的催化性能,表明结构本体相对OER催化的影响可忽略不计。因此,应该怀疑仅从整体性质得到的钙钛矿催化剂的合理设计路线。
更新日期:2017-09-20
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