催化学报 ›› 2025, Vol. 74: 411-424.DOI: 10.1016/S1872-2067(25)64691-2

• 论文 • 上一篇    下一篇

石墨二炔负载的d8态Fe双原子催化剂耦合-解耦自旋态转换机制研究

朱晓辉a, 邢浩然b, 何光裕a, 肖海c, 陈银娟a,*(), 李隽d,e   

  1. a江苏省绿色催化材料与技术重点实验室, 先进催化与绿色制造协同创新中心, 江苏常州 213164
    b南京大学化学与化学工程学院, 配位化学国家重点实验室, 先进微结构协同创新中心, 江苏南京 210023
    c清华大学化学系, 北京 100084
    d清华大学化学系理论化学中心, 稀土新材料教育部工程研究中心, 北京 100084
    e中国科学院赣江创新研究院稀土基础科学中心, 江西赣州 341119
  • 收稿日期:2025-01-06 接受日期:2025-03-18 出版日期:2025-07-18 发布日期:2025-07-20
  • 通讯作者: *电子信箱: chen_yinjuan@hotmail.com (陈银娟).
  • 基金资助:
    江苏省自然科学基金(BK20220618);江苏省研究生科研与实践创新计划(KYCX24_3199);国家自然科学基金基础科学中心项目“单原子催化”(22388102)

Insights into the couple-decouple spin state shifting of graphdiyne-supported d8 state Fe dual-atom catalysts

Xiaohui Zhua, Haoran Xingb, Guangyu Hea, Hai Xiaoc, Yinjuan Chena,*(), Jun Lid,e   

  1. aKey Laboratory of Advanced Catalytic Materials and Technology, Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou 213164, Jiangsu, China
    bState Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Street, Nanjing 210023, Jiangsu, China
    cDepartment of Chemistry, Tsinghua University, Beijing 100084, China
    dDepartment of Chemistry and Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education, Tsinghua University, Beijing 100084, China
    eFundamental Science Center of Rare Earths, Ganjiang Innovation Academy, Chinese Academy of Sciences, Ganzhou 341119, Jiangxi, China
  • Received:2025-01-06 Accepted:2025-03-18 Online:2025-07-18 Published:2025-07-20
  • Contact: *E-mail: chen_yinjuan@hotmail.com (Y. Chen).
  • Supported by:
    Natural Science Foundation of Jiangsu Province(BK20220618);Postgraduate Research & Practice Innovation Program of Jiangsu Province(KYCX24_3199);NSFC Center for Single-Atom Catalysis(22388102)

摘要:

作为单原子催化剂(SACs)的自然延伸, 双原子催化剂(DACs)具有原子负载量大、双原子邻近位点潜在协同作用、多功能化的活性位点和独特的反应机制等优点, 已经成为化学和能源转化过程非均相催化领域的主要研究热点之一. 与SACs相比, DACs表现出更为复杂的电子相互作用和协同效应. 研究表明, 第二个金属原子的引入可以有效调控金属中心的电子结构和自旋态. 其中, 自旋态作为催化剂电子结构和电催化性能相关联的关键描述符引起了学界热烈地讨论. 近年来, 大量探索性研究考察了自旋态与催化特性之间的构-效关系, 但针对具体催化剂特定原子水平结构与自旋特性之间的固有关联仍鲜见报道. 因此, 研究电子自旋态与催化活性中心本征拓扑结构及几何结构之间的构-效关系具有重要意义.

本文以具有共轭二炔链(−C≡C−C≡C−)C18基团构筑的三角形本征孔结构的石墨二炔(GDY)为载体, 综合考虑GDY拓扑结构及第二个金属原子相对负载位点变化, 设计了16种Fe双原子催化剂Fe2-GDYn. 通过计算金属原子的结合能, 发现所有结构的结合能均在−7 eV以下, 确保了所有设计DACs的热力学稳定性. 并以两个金属原子的直线距离d和其到GDY所在平面的垂直距离差d作为关键描述符, 标记Fe2-GDYn的几何特性. 采用高精度磁基态收敛策略来研究电子组态和自旋态, 并以反铁磁(AFM)和铁磁(FM)态能量差ΔE = EAFM - EFM作为自旋基态评判标准, 对Fe2-GDYn进行自旋特征的定性和定量分析. 研究表明, 当垂直距离差d ≥ 0.294 Å时, 两个铁原子的自旋态相反; 当d ≤ 0.034 Å时, 两个铁原子的自旋态相同; 当d在0.034−0.294 Å范围内, 自旋态在FM和AFM之间随机出现. 在此基础上, 根据GDY骨架本征孔结构特性, 定义铁原子之间最短响应键的间隔数Ntot (Ntot = Nσ + Nσ+π + Nσ+2π, 其中Nσ, Nσ+πNσ+2π分别为两个铁原子之间C−C, C=C和C≡C键的数量)和π% (π% = (Nσ+π + 2*Nσ+2π)/Ntot)被作为新的描述符. 研究发现, 除了Fe2-GDY0和Fe2-GDY3表现出明显的FM特性, 其他结构的∆E均小于化学精度, 即1 kcal mol-1 (0.043 eV). 此外, 有十个结构具有较小|ΔE|值, 且均满足π% ≥ 60%. 表明离域π电子的存在导致铁原子之间的自旋态解耦, 无法明确区分其FM和AFM态. 两个铁原子之间的自旋耦合主要受到相邻短程Fe-Fe相互作用的主导, 而自旋解耦则可归因于最短相应键内的长程π键成分. 对Fe−C键和PDOS能级分布的研究揭示了Fe 3d轨道中的显著轨道分裂, 其轨道分裂模式受到两个d8铁原子的几何和化学键合对称性变化的影响. 此外, 针对典型Fe2-GDYn结构单位点ORR理论机制研究表明, 不同Fe2-GDYn几何结构和电子性质直接导致其最优ORR路径及决速步自由能垒产生显著差异.

综上, 本文采用密度泛函理论计算, 结合载体的结构特征及双原子位点分布, 深入探究了DACs拓扑结构、自旋与催化性能的构-效关系. 该研究有望为S/DACs周期性模型精确自旋特性的研究提供借鉴, 以期促进自旋调控S/DACs的理性设计.

关键词: 双原子催化剂, 石墨二炔, 理性设计, 电子结构, 自旋态

Abstract:

Dual-atom catalysts (DACs), a natural extension of single-atom catalysts (SACs), have emerged as a prominent focal point in the field of heterogeneous catalysis, particularly in the context of chemical and energy conversion processes. Despite the fact that the catalytic activity of DACs is significantly modulated by the electronic structure of the catalyst, understanding how electron spin states are affected by variations in topology and geometric structure remains challenging and relatively unexplored. Herein, we propose the rational design of stable DACs composed of two iron atoms anchored on pristine graphdiyne (GDY), Fe2-GDYn. A comprehensive and systematic investigation was carried out to elucidate the electronic configuration and spin states involved in the deliberate convergence towards the magnetic ground state, with the aim of uncovering the structure-spin relationship. Through an in-depth analysis of spin populations, electronic localization/delocalization, and the chemical bonding characteristics of the central metal atoms and the GDY skeleton, it was revealed that the spin coupling between the two iron atoms is preponderantly dictated by adjacent short-range Fe-Fe interactions. Conversely, spin decoupling can be attributed to the long-range π-bond component within the linkage. Moreover, geometric and chemical bonding asymmetries were found to induce orbital and spin splitting in iron atoms possessing an electronic configuration of d8. These findings provide important insights into the relationship between topology and spin, thereby presenting novel strategies for the rational design of spin-manipulated DACs.

Key words: Dual-atom catalysts, Graphdiyne, Rational design, Electronic structure, Spin state