Developing highly stable and efficient catalysts for oxygen evolution reaction (OER) is extremely important to sustainable energy conversion and storage, but improved efficiency is largely hindered by sluggish reaction kinetics. Dense and bimetal ruthenates have emerged as one of the promising substitutes to replace single-metal ruthenium or iridium oxides, but the fundamental understanding the role of A-site cations is still blurring. Herein, a family of lanthanides (Ln = all the lanthanides except Pm) are applied to synthesize pyrochlore lanthanide ruthenates (LnRuO), and only LnRuO (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) with pure phase can be obtained by the ambient-pressure calcination. Compared with the perovskite ruthenates (SrRuO) and rutile RuO, the [RuO] units in these LnRuO present the largely distorted configurations and different energy level splitting to prevent the excessive Ru oxidation and dissolution, which leads the primary improvement in the electrocatalytic OER performance. In the similar crystalline field split states, the charge transfer between [RuO] units and Ln cations also affect catalytic activities, even in the LnRuO surface reconstruction during the OER process. Consequently, TbRuO showed the highest OER performance among all the prepared LnRuO with similar morphologies and crystallization. This systematic work gives fundamental cognition to rational design of high-performance OER electrocatalysts in proper water electrolysis technologies.

中文翻译：

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烧绿石稀土钌酸A位在电催化析氧反应中的作用


开发用于析氧反应（OER）的高度稳定和高效的催化剂对于可持续的能源转换和存储极其重要，但缓慢的反应动力学在很大程度上阻碍了效率的提高。致密双金属钌酸盐已成为替代单金属钌或氧化铱的有前途的替代品之一，但对 A 位阳离子的作用的基本了解仍然模糊。本文采用镧系元素家族（Ln=除Pm之外的所有镧系元素）来合成烧绿石镧系元素钌酸盐（LnRuO），并且仅LnRuO（Ln=Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、或Lu)可以通过常压煅烧获得纯相。与钙钛矿钌酸盐（SrRuO）和金红石RuO相比，这些LnRuO中的[RuO]单元呈现出大幅扭曲的构型和不同的能级分裂，以防止Ru过度氧化和溶解，从而导致电催化OER性能的初步改善。在类似的晶体场分裂状态下，[RuO]单元和 Ln 阳离子之间的电荷转移也会影响催化活性，甚至在 OER 过程中的 LnRuO 表面重构中也是如此。因此，在所有制备的具有相似形貌和结晶的LnRuO中，TbRuO表现出最高的OER性能。这项系统工作为在适当的水电解技术中合理设计高性能 OER 电催化剂提供了基础认知。