Electrocatalytic reactions are known to take place at the catalyst/electrolyte interface. Whereas recent studies of size-dependent activity in nanoparticles and thickness-dependent activity of thin films imply that the sub-surface layers of a catalyst can contribute to the catalytic activity as well, most of these studies consider actual modification of the surfaces. In this study, the role of catalytically active sub-surface layers was investigated by employing atomic-scale thickness control of the La_0.7Sr_0.3MnO₃ (LSMO) films and heterostructures, without altering the catalyst/electrolyte interface. The activity toward the oxygen evolution reaction (OER) shows a non-monotonic thickness dependence in the LSMO films and a continuous screening effect in LSMO/SrRuO₃ heterostructures. The observation leads to the definition of an “electrochemically-relevant depth” on the order of 10 unit cells. This study on the electrocatalytic activity of epitaxial heterostructures provides new insight in designing efficient electrocatalytic nanomaterials and core-shell architectures.

中文翻译：

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亚表面对原子级精确 La0.7Sr0.3MnO3 异质结构电催化活性的贡献

已知电催化反应发生在催化剂/电解质界面处。尽管最近对纳米颗粒的尺寸依赖性活性和薄膜的厚度依赖性活性的研究表明催化剂的亚表面层也可以促进催化活性，但这些研究中的大多数都考虑了表面的实际改性。在这项研究中，通过采用原子级厚度控制 La _0.7 Sr _0.3 MnO _{3 来}研究催化活性次表面层的作用。(LSMO) 薄膜和异质结构，而不会改变催化剂/电解质界面。对析氧反应 (OER) 的活性显示出 LSMO 薄膜中的非单调厚度依赖性和 LSMO/SrRuO ₃异质结构中的连续屏蔽效应。观察结果导致定义了 10 个单元格数量级的“电化学相关深度”。这项关于外延异质结构电催化活性的研究为设计高效的电催化纳米材料和核壳结构提供了新的见解。