Electrocatalytic splitting of water is a promising method of hydrogen generation. Here, we report an enhanced electrocatalytic performance for water electrolysis, achieved through a progressive increase in the ordering of oxygen vacancies in the structural network of oxides. In transition from Sr₂FeCoO_6−δ (disordered) to CaSrFeCoO_6−δ (ordered) and Ca₂FeCoO_6−δ (highly ordered), the change in the average ionic radius of the A-site metals leads to an increase in the concentration and ordering of oxygen vacancies, resulting in a progressive enhancement of the electrocatalytic activity for both cathodic and anodic half-reactions of water splitting, i.e., hydrogen-evolution (HER) and oxygen-evolution (OER) reactions. The OER electrocatalysis is particularly important, as it is considered the bottleneck for water electrolysis. These electrocatalysts show better activity than the precious metal catalyst RuO₂. In contrast to most bifunctional catalysts reported to date, these catalysts can be used in bulk form, without the need for nanofabrication, composite formation, or any additional processing. Density functional theory calculations indicate that the vacancy order leads to a shift of the electronic bands toward the Fermi level. We propose that the ordering of oxygen vacancies can be used as a handle for the design of highly active electrocatalysts.

中文翻译：

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作为钙钛矿氧化物结构有序函数的电催化活性增强

水的电催化分解是一种很有前途的制氢方法。在这里，我们报告了增强的水电解电催化性能，这是通过逐步增加氧化物结构网络中氧空位的有序性来实现的。从 Sr ₂ FeCoO _6-δ（无序）到 CaSrFeCoO _6-δ（有序）和 Ca ₂ FeCoO _{6-δ 的转变}（高度有序），A位金属的平均离子半径的变化导致氧空位的浓度和有序性的增加，导致水的阴极和阳极半反应的电催化活性逐渐增强分裂，即析氢（HER）和析氧（OER）反应。OER 电催化尤为重要，因为它被认为是水电解的瓶颈。这些电催化剂表现出比贵金属催化剂RuO _{2更好的活性}. 与迄今为止报道的大多数双功能催化剂相比，这些催化剂可以以散装形式使用，无需纳米加工、复合材料形成或任何额外的加工。密度泛函理论计算表明，空位顺序导致电子能带向费米能级移动。我们建议氧空位的排序可以作为设计高活性电催化剂的一个手段。