物理化学学报 >> 2024, Vol. 40 >> Issue (6): 2307015.doi: 10.3866/PKU.WHXB202307015

所属专题： 电催化功能材料

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双层单原子催化剂用于促进高活性和选择性电催化硝酸盐还原制氨

于镜坤1, 雍雪2,*(), 曹昂3, 卢思宇1,*()   

  1. 1 郑州大学, 化学学院绿色催化中心, 郑州 450001
    2 Department of Chemistry, University of Sheffield, Sheffield, S37HF, UK
    3 Department of Physics, Technical University of Denmark, Kongens Lyngby 2800, Denmark
  • 收稿日期:2023-07-06 修回日期:2023-08-22 录用日期:2023-08-23 发布日期:2023-11-29
  • 通讯作者: Email: sylu2013@zzu.edu.cn (卢思宇)x.yong@sheffield.ac.uk (雍雪)
  • 基金资助:
    国家自然科学基金项目(51973200); 国家自然科学基金项目(52122308); 郑州国家超级计算中心资助

Bi-Layer Single Atom Catalysts Boosted Nitrate-to-Ammonia Electroreduction with High Activity and Selectivity

Jingkun Yu1, Xue Yong2,*(), Ang Cao3, Siyu Lu1,*()   

  1. 1 Green Catalysis Center, and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
    2 Department of Chemistry, University of Sheffield, Sheffield, S37HF, UK
    3 Department of Physics, Technical University of Denmark, Kongens Lyngby 2800, Denmark
  • Received:2023-07-06 Revised:2023-08-22 Accepted:2023-08-23 Published:2023-11-29
  • Contact: Email: sylu2013@zzu.edu.cn (Siyu Lu)x.yong@sheffield.ac.uk (Xue Yong)
  • Supported by:
    the National Natural Science Foundation of China(51973200); the National Natural Science Foundation of China(52122308); the National Supercomputing Center in Zhengzhou, China

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摘要：

高效、高选择性的单原子催化剂(SACs)在电催化硝酸盐还原制氨过程中具有重要作用。然而，由于中间体、金属活性中心和配位环境之间复杂的竞争性电子相互作用，仍然面临挑战。本研究采用密度泛函理论(DFT)计算，对27种SACs以及双层SACs (BSACs)进行了系统研究，通过轴向d–d轨道杂化提高了从SACs到BSACs的电催化硝酸盐还原反应(NO3RR)的活性和选择性。考虑到可能的O端、N端、NO端和NO二聚体途径，计算结果显示，在单层SACs中，Ti-Pc和V-Pc分别具有优异的极限电位(UL)，分别为−0.24和−0.48 V。形成能、溶解势以及从头算分子动力学结果表明，在反应条件下，这些催化剂非常稳定。在这些单层TM-Pc中，它们的d带能级和占据数受到dxz/dyz和pz轨道杂化的影响。其轴向dz2轨道的可用性通过形成dz2–dz2相互作用来进一步调整d带和反应性。在此基础上，以Ti-Pc和V-Pc为底物，通过形成轴向d–d轨道杂化来构建BSACs，为调节NO3RR催化性能提供了一种独特的新途径。重要的是，我们发现d带中心(εd)、dxz + dyz轨道的占据数和UL之间存在二维火山关系，用于描述它们的NO3RR催化性能。最佳的BSACs应该同时具备适当的εd和dxz + dyz占用数。Ti-Mo和Ti-Ta被确定为出色的NO3RR催化剂，其UL均降低至−0.13 V。而dz2–dz2轨道之间的杂化则增强了双层金属之间的电荷转移和结构稳定性。缺乏相邻的金属位点将导致生成NO2、NO和N2的能垒较高，从而抑制副产物生成。最终，本研究揭示了在SACs和BSACs上对硝酸盐还原进行合理优化的方法，可为改进电催化剂的设计提供指导。

关键词: 硝酸盐还原, 第一性原理计算, 单原子催化剂, 双层单原子催化剂, 轴向轨道杂化

Abstract:

Designing efficient single-atom catalysts (SACs) with high selectivity for the electrocatalytic reduction of nitrate to ammonia formation is both crucial and challenging. This challenge arises due to the intricate and competitive electronic interactions among intermediates, metal active centers, and coordination environments. In this work, we present a comprehensive investigation detailing how to enhance the activity and selectivity of the electrocatalytic nitrate reduction reaction (NO3RR) by transitioning from single-layer SACs to bilayer SACs (BSACs). This enhancement is achieved through axial d–d orbital hybridization, as elucidated by a systematic study of 27 SACs and BSACs utilizing density functional theory (DFT) calculations. Considering potential pathways involving O-terminal, N-terminal, NO-terminal, and NO-dimer configurations, our calculations reveal that among monolayer SAC candidates, Ti-Pc and V-Pc exhibit low limiting potentials (UL) of −0.24 and −0.48 V, respectively. Furthermore, analyses of formation energy, dissolution potential, and ab initio molecular dynamics results demonstrate the robust stability of these catalysts under reaction conditions. In these single-layer transition metal (TM)-Pc complexes, the d-band energy levels and occupation numbers are influenced by dxz/dyz and pz orbital hybridizations. Notably, the presence of axial dz2 orbitals introduces a novel avenue for fine-tuning d-band characteristics and reactivity through dz2–dz2 interactions. Building on these insights, the formation of BSACs using Ti-Pc and V-Pc as substrates, facilitated by axial d–d orbital hybridization, offers a distinctive approach to modulating the catalytic performance of NO3RR. Significantly, we establish a two-dimensional volcano correlation encompassing the d-band center (εd), dxz + dyz orbital occupation numbers, and UL to describe NO3RR catalytic efficacy. Optimal BSACs should possess concurrent appropriate εd and dxz + dyz occupation numbers. Remarkably, Ti-Mo and Ti-Ta BSACs emerge as exceptional NO3RR catalyst candidates, both displaying a remarkably low UL of −0.13 V. The hybridization between dz2–dz2 orbitals heightens charge transfer and structural stability within double-layer metals. The scarcity of contiguous metal sites introduces a substantial energy barrier hindering NO2, NO, and N2 formation, effectively suppressing NO3RR by-products. In summation, this investigation imparts valuable insights into effectively enhancing nitrate reduction on SACs and BSACs, offering valuable guidance for advancing electrocatalyst development.

Key words: Nitrate reduction, First-principles calculation, Single-atom catalysts, Bilayer single-atom catalysts, Axial orbital hybridization