Electrocatalytic water splitting provides a sustainable method for storing intermittent energies, such as solar energy and wind, in the form of hydrogen fuel. However, the oxygen evolution reaction (OER), constituting the other half-cell reaction, is often considered the bottleneck in overall water splitting due to its slow kinetics. Therefore, it is crucial to develop efficient, cost-effective, and robust OER catalysts to enhance the water-splitting process. Transition-metal-based coordination polymers (CPs) serve as promising electrocatalysts due to their diverse chemical architectures paired with redox-active metal centers. Despite their potential, the rational use of CPs has faced obstacles including a lack of insights into their catalytic mechanisms, low conductivity, and morphology issues. Consequently, achieving success in this field requires the rational design of ligands and topological networks with the desired electronic structure. This study delves into the design and synthesis of three novel conjugated coordination polymers (CCPs) by leveraging the full conjugation of terpyridine-attached flexible tetraphenylethylene units as electron-rich linkers with various redox-active metal centers [Co(II), Ni(II), and Zn(II)]. The self-assembly process is tuned for each CCP, resulting in two distinct morphologies: nanosheets and nanorings. The electrocatalytic OER performance efficiency is then correlated with factors such as the nanostructure morphology and redox-active metal centers in alkaline electrolytes. Notably, among the three morphologies studied, nanorings for each CCP exhibit a superior OER activity. Co(II)-integrated CCPs demonstrate a higher activity between the redox-active metal centers. Specifically, the Co(II) nanoring morphology displays exceptional catalytic activity for OER, with a lower overpotential of 347 mV at a current density of 10 mA cm^–2 and small Tafel slopes of 115 mV dec^–1. The long-term durability is demonstrated for at least 24 h at 1.57 V vs RHE during water splitting. This is presumably the first proof that links the importance of nanostructure morphologies to redox-active metal centers in improving the OER activity, and it may have implications for other transdisciplinary energy-related applications.

中文翻译：

---

自组装共轭配位聚合物纳米环：形态和氧化还原位点在碱性电催化析氧反应中的作用


电催化水分解提供了一种以氢燃料形式存储间歇性能源（例如太阳能和风能）的可持续方法。然而，构成另一种半电池反应的析氧反应（OER）由于其动力学缓慢，通常被认为是整个水分解的瓶颈。因此，开发高效、经济且稳定的 OER 催化剂来增强水分解过程至关重要。基于过渡金属的配位聚合物（CP）因其多样化的化学结构与氧化还原活性金属中心相结合而成为有前景的电催化剂。尽管CPs具有潜力，但其合理使用仍面临障碍，包括缺乏对其催化机制、低电导率和形态问题的深入了解。因此，要在该领域取得成功，需要合理设计具有所需电子结构的配体和拓扑网络。本研究通过利用三联吡啶连接的柔性四苯乙烯单元作为富电子连接体与各种氧化还原活性金属中心 [Co(II)、Ni(II) 的完全共轭，深入研究了三种新型共轭配位聚合物 (CCP) 的设计和合成。 ）和锌（II）]。自组装过程针对每个 CCP 进行调整，产生两种不同的形态：纳米片和纳米环。然后，电催化 OER 性能效率与纳米结构形态和碱性电解质中的氧化还原活性金属中心等因素相关。值得注意的是，在研究的三种形态中，每个 CCP 的纳米环都表现出优异的 OER 活性。 Co(II) 集成的 CCP 在氧化还原活性金属中心之间表现出更高的活性。 具体来说，Co(II) 纳米环形态对 OER 表现出优异的催化活性，在 10 mA cm ^–2 的电流密度下具有 347 mV 的较低过电位和 115 mV dec ^–1