Ru-Substituted MnO2 for Accelerated Water Oxidation: The Feedback of Strain-Induced and Polymorph-Dependent Structural Changes to the Catalytic Activity and Mechanism,ACS Catalysis

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Ru-Substituted MnO2 for Accelerated Water Oxidation: The Feedback of Strain-Induced and Polymorph-Dependent Structural Changes to the Catalytic Activity and Mechanism
ACS Catalysis ( IF 11.3 ) Pub Date : 2022-12-15 , DOI: 10.1021/acscatal.2c04759
Yongze Qin _{1,

2} , Yu Liu ₁ , Yanzhi Zhang _{1,

2} , Yindong Gu _{1,

2} , Yuebin Lian ₁ , Yanhui Su _{1,

2} , Jiapeng Hu ₁ , Xiaohui Zhao ₁ , Yang Peng ₁ , Kun Feng ₃ , Jun Zhong ₃ , Mark H. Rummeli ₁ , Zhao Deng _{1,

2}

Affiliation

Heteroatomic modulation of MnO₂ is an effective way to introduce and tailor the catalytically active sites for electrochemical water oxidation. While great efforts have been devoted to parsing the configuration and coordination of dopants in dictating the catalytic activity, less is considered about the feedback from the structurally adapted MnO₂ host to the intrinsic activity of catalytic sites. In this study, the topological effect on oxygen evolution reaction (OER) activity was systemically investigated for partially Ru-substituted MnO₂ of various polymorphs. We show that MnO₂ of different porosities responds differently to the Ru integration, thereby resulting in varied lattice strains and morphological changes. While the highly porous τ-MnO₂ undergoes amorphization upon Ru substitution, the closely packed β-MnO₂ suffers crystal splintering with drastically enhanced structural defects, which lends to a low OER overpotential of 278 mV at 10 mA cm^–2 and a high turnover frequency of 2022.2 h^–1 that is 19.6-fold higher than that of the commercial RuO₂ benchmark. Therefore, the integration of Ru does not simply append active sites to the relatively inert metal oxides but simultaneously modifies the crystal structure of MnO₂ to retroactively modulate the catalytic activity. We further show that OER on the Ru-substituted β-MnO₂ follows a lattice oxygen mechanism as a result of the adapted oxide substrate. This study furnishes a fresh and systemic view on the dopant–substrate interplay for modulating the electrocatalytic activity of tunneled MnO₂ structures.

中文翻译：

用于加速水氧化的 Ru 取代 MnO2：应变诱导和多晶型相关的结构变化对催化活性和机理的反馈

MnO ₂的杂原子调制是引入和调整电化学水氧化催化活性位点的有效方法。虽然已经付出了巨大的努力来分析掺杂剂在决定催化活性方面的构型和配位，但很少有人考虑结构适应的 MnO ₂主体对催化位点固有活性的反馈。在这项研究中，系统研究了各种晶型的部分 Ru 取代的 MnO ₂对析氧反应 (OER) 活性的拓扑效应。我们证明 MnO ₂不同孔隙率对 Ru 积分的响应不同，从而导致不同的晶格应变和形态变化。当高度多孔的 τ-MnO ₂在 Ru 取代时经历非晶化，而紧密堆积的 β-MnO _{2遭受晶体分裂，结构缺陷显着增强，这导致在 10 mA cm}^–2下的低 OER 过电势为 278 mV和高周转率2022.2 h ^{–1的频率是商业 RuO}₂基准的 19.6 倍。因此，Ru的结合并不是简单地将活性位点附加到相对惰性的金属氧化物上，而是同时改变了MnO _{2的晶体结构}追溯调节催化活性。我们进一步表明，由于适应的氧化物基板，Ru 取代的 β-MnO ₂上的 OER遵循晶格氧机制。这项研究为掺杂剂-底物相互作用调节隧道 MnO ₂结构的电催化活性提供了一个全新的系统观点。

更新日期：2022-12-15

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