Prussian blue analogs (PBAs) are promising catalysts for green hydrogen production. However, the rational design of high-performing PBAs is challenging, which requires an in-depth understanding of the catalytic mechanism. Here FeMn@CoNi core–shell PBAs are employed as precursors, together with Se powders, in low-temperature pyrolysis in an argon atmosphere. This synthesis method enables the partial dissociation of inner FeMn PBAs that results in hollow interiors, Ni nanoparticles (NPs) exsolution to the surface, and Se incorporation onto the PBA shell. The resulting material presents ultralow oxygen evolution reaction (OER) overpotential (184 mV at 10 mA cm⁻²) and low Tafel slope (43.4 mV dec⁻¹), outperforming leading-edge PBA-based electrocatalysts. The mechanism responsible for such a high OER activity is revealed, assisted by density functional theory (DFT) calculations and the surface examination before and after the OER process. The exsolved Ni NPs are found to help turn the PBAs into Se-doped core–shell metal oxyhydroxides during the OER, in which the heterojunction with Ni and the Se incorporation are combined to improve the OER kinetics. This work shows that efficient OER catalysts could be developed by using a novel synthesis method backed up by a sound understanding and control of the catalytic pathway.

中文翻译：

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增强普鲁士蓝类似物的析氧反应性能：金属溶出、中空内部和阴离子调节的三重作用

普鲁士蓝类似物（PBA）是有前途的绿色氢生产催化剂。然而，高性能PBA的合理设计具有挑战性，需要深入了解催化机制。这里采用 FeMn@CoNi 核壳 PBA 作为前体，与 Se 粉末一起在氩气气氛中进行低温热解。这种合成方法使得内部 FeMn PBA 部分解离，导致内部空心，Ni 纳米颗粒 (NP) 溶出到表面，Se 结合到 PBA 壳上。所得材料具有超低析氧反应（OER）过电势（10 mA cm ^-2时为184 mV ）和低塔菲尔斜率（43.4 mV dec ^-1），优于领先的基于PBA的电催化剂。在密度泛函理论 (DFT) 计算和 OER 过程前后的表面检查的辅助下，揭示了造成如此高 OER 活性的机制。研究发现，在 OER 过程中，溶出的 Ni NPs 有助于将 PBA 转化为 Se 掺杂的核壳金属羟基氧化物，其中 Ni 的异质结和 Se 的掺入相结合，以改善 OER 动力学。这项工作表明，通过使用一种新的合成方法，通过对催化途径的充分理解和控制，可以开发高效的 OER 催化剂。