Coordination Symmetry Breaking of Single-Atom Catalysts for Robust and Efficient Nitrate Electroreduction to Ammonia,Advanced Materials

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Coordination Symmetry Breaking of Single-Atom Catalysts for Robust and Efficient Nitrate Electroreduction to Ammonia
Advanced Materials ( IF 27.4 ) Pub Date : 2022-07-15 , DOI: 10.1002/adma.202205767
Xue-Feng Cheng ₁ , Jing-Hui He ₁ , Hao-Qing Ji ₂ , Hao-Yu Zhang ₁ , Qiang Cao ₁ , Wu-Ji Sun ₁ , Cheng-Lin Yan ₂ , Jian-Mei Lu ₁

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Nitrate electrocatalytic reduction (NO₃RR) for ammonia production is a promising strategy to close the N-cycle from nitration contamination, as well as an alternative to the Haber–Bosch process with less energy consumption and carbon dioxide release. However, current long-term stability of NO₃RR catalysts is usually tens of hours, far from the requirements for industrialization. Here, symmetry-broken Cusingle-atom catalysts are designed, and the catalytic activity is retained after operation for more than 2000 h, while an average ammonia production rate of 27.84 mg h⁻¹ cm⁻² at an industrial level current density of 366 mA cm⁻² is achieved, obtaining a good balance between catalytic activity and long-term stability. Coordination symmetry breaking is achieved by embedding one Cu atom in graphene nanosheets with two N and two O atoms in the cis-configuration, effectively lowering the coordination symmetry, rendering the active site more polar, and accumulating more NO₃⁻ near the electrocatalyst surface. Additionally, the cis-coordination splits the Cu 3d orbitals, which generates an orbital-symmetry-matched π-complex of the key intermediate *ONH and reduces the energy barrier, compared with the σ-complex generated with other catalysts. These results reveal the critical role of coordination symmetry in single-atom catalysts, prompting the design of more coordination-symmetry-broken electrocatalysts toward possible industrialization.

中文翻译：

单原子催化剂的配位对称性破缺以实现稳健高效的硝酸盐电还原制氨

用于氨生产的硝酸盐电催化还原 (NO ₃ RR) 是关闭 N 循环免受硝化污染的一种有前途的策略，也是 Haber-Bosch 工艺的替代方案，能耗和二氧化碳排放更少。_{然而，目前NO 3} RR催化剂的长期稳定性通常为数十小时，远远达不到工业化的要求。在这里，设计了对称破缺的Cusingle原子催化剂，在366 mA的工业水平电流密度下，催化活性在运行2000 h以上后仍保持不变，平均产氨率为27.84 mg h ^-1 cm ^-2厘米^-2达到了催化活性和长期稳定性之间的良好平衡。通过将一个Cu原子嵌入石墨烯纳米片中实现配位对称性破坏，其中两个N和两个O原子呈顺式构型，有效地降低了配位对称性，使活性位点更具极性，并在电催化剂表面附近积累更多的NO ₃^{- 。}此外，顺式-配位分裂Cu 3d轨道，与其他催化剂产生的σ配合物相比，产生关键中间体*ONH的轨道对称匹配的π配合物并降低能垒。这些结果揭示了配位对称性在单原子催化剂中的关键作用，促使设计更多的配位对称性破坏电催化剂走向可能的工业化。

更新日期：2022-07-15

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