催化学报 ›› 2027, Vol. 92: 123-129.DOI: 10.1016/S1872-2067(26)65217-5

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前线分子轨道理论揭示零价单原子催化剂的稳定性与活性机制

徐余幸a, 李胤a, 王恒伟a, 滕波涛b, 路军岭a,*   

  1. a中国科学技术大学化学与材料科学学院, 精准智能化学全国重点实验室, 安徽合肥 230026;
    b天津科技大学化工与材料学院, 天津市卤水化工与资源生态化利用重点实验室, 天津 300457
  • 收稿日期:2026-03-02 接受日期:2026-06-03 出版日期:2027-01-18 发布日期:2026-10-30
  • 通讯作者: *电子信箱: junling@ustc.edu.cn (路军岭).
  • 基金资助:
    国家自然科学基金(22532005, 22202190, 92477136); 中国科学技术大学前沿科学重大研究计划(LS2060000002); 中国科学院机器人AI-Scientist平台, 中国科学院前沿科学重点研究项目(ZDBS-LY-SLH003); 同步辐射联合基金(KY2060000258); USTC-GIA-REGCC-Ganzhou联合基金(FU2025C003).

Frontier orbital insights into the stability and activity of zero-valent single-atom catalysts

Yuxing Xua, Yin Lia, Hengwei Wanga, Botao Tengb, Junling Lua,*   

  1. aKey Laboratory of Precision and Intelligent Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, Anhui, China;
    bTianjin Key Laboratory of Brine Chemical Engineering and Resource Eco-utilization, College of Chemical Engineering and Materials Science, Tianjin University of Science and Technology, Tianjin 300457, China
  • Received:2026-03-02 Accepted:2026-06-03 Online:2027-01-18 Published:2026-10-30
  • Contact: *E-mail: junling@ustc.edu.cn (J. Lu).
  • Supported by:
    National Natural Science Foundation of China (22532005, 22202190, 92477136), the Major Frontier Research Project of the University of Science and Technology of China (LS2060000002), the robotic AI-Scientist platform of Chinese Academy of Sciences, the Key Research Program of Frontier Sciences, CAS (ZDBS-LY-SLH003), the National Synchrotron Radiation Laboratory (KY2060000258), and the USTC-GIA-REGCC-Ganzhou Joint Fund (FU2025C003).

摘要: 单原子催化剂因结构明确, 金属利用率高和独特电子性质, 在加氢等反应中具有重要应用潜力. 然而, 孤立金属原子表面自由能高, 易迁移并聚集失活, 尤其在高温涉氢反应中稳定性问题更突出. 传统观点认为, 强金属-载体相互作用源于金属向载体的显著电荷转移, 并通常表现为较高金属氧化态. 但近年来低价甚至零价单原子催化剂也表现出优异活性和稳定性, 说明高稳定性并不一定依赖强电荷转移. 因此, 从轨道层面揭示金属-载体相互作用的本质对于理解其稳定机制至关重要, 但相关研究仍极为有限.
本文以B掺杂g-C3N4负载近零价Pd1单原子催化剂(Pd1/BCN)为模型, 引入FMO理论, 发现Pd1原子与载体之间的能级为交错型结构, 继而存在两个前线轨道耦合通道. 首先, 通过密度泛函理论计算比较了g-C3N4与BCN的电子结构. 结果表明, B掺杂显著调控了载体能带结构, 使带隙由1.18缩至0.73 eV, 并同时调节载体HOS和LUS的位置, 为Pd1与载体之间形成更强前线轨道耦合提供了条件. 结构优化显示, Pd1在两种载体上均主要锚定于孔边吡啶N1位点, 但Pd1/BCN中Pd–N键明显缩短, 吸附能由Pd1/g-C3N4的−2.03增至−2.19 eV, 说明B掺杂提高了Pd1的稳定性. 与此同时, Bader电荷分析表明, Pd1/BCN中Pd1仅带0.27|e|正电, 低于Pd1/g-C3N4的0.49 |e|, 更接近零价Pd1; 差分电荷密度也显示Pd1周围存在更明显的电子积累, 说明载体向金属的电子反馈增强. 进一步的PDOS分析揭示, 气相Pd1的HOMO位于载体N1的HOMO与LUMO之间, 形成交错能级排列, 从而产生两个协同通道: 一方面, Pd1 HOMO向N1 LUMO供电子; 另一方面, N1 HOMO向Pd1 LUMO反馈电子. B掺杂同时缩小这两个通道的能级差, 使双向耦合更强, Pd1价态接近零价, 而且呈现更高稳定性. 积分晶体轨道哈密顿布居(ICOHP)结果进一步表明, Pd1/BCN中Pd–N键的ICOHP值为−1.89 eV, 明显强于Pd1/g-C3N4的−1.31 eV, 验证了轨道耦合增强带来的Pd1单原子稳定性提升. 在反应性能方面, Pd1/BCN对H2活化表现出更优动力学和热力学特征. 尽管两种催化剂上吸附H2的H–H键长接近, 但Pd1/BCN上H2解离能垒仅为0.54 eV, 显著低于Pd1/g-C3N4的1.07 eV, 且反应能由−0.05降至−0.49 eV. 其原因在于富电子Pd1/BCN能更有效地向H2的反键轨道供电子, 并与解离后的H原子形成更强Pd–H轨道杂化, 从而促进H–H键断裂并稳定反应产物.
综上, 本工作首次基于FMO理论在轨道层面上揭示了零价Pd1 SACs的稳定性与催化活性问题, 建立了从载体能带结构和轨道耦合出发理解单原子稳定性与活性的统一框架, 该理论有望进一步拓展至其他金属单原子、掺杂载体及加氢、脱氢和电催化反应体系. 为实现SACs催化剂的理性设计提供了有益的理论指导.

关键词: 单原子催化剂, 金属-载体相互作用, 前线轨道理论, 稳定性, 加氢反应

Abstract: The stability of single-atom catalysts (SACs) has been a major concern for their practical applications. The orbital-level understanding of the nature of metal-support interaction is of essential importance, but has been rarely reported. Here, frontier molecular orbital (FMO) theory is employed to investigate the stabilization mechanism of a nearly zero-valent Pd1 catalyst supported on boron-doped g-C3N4 (Pd1/BCN). We demonstrate that the exceptional stability originates from enhanced frontier orbital coupling under a staggered energy-level alignment between the Pd1 atom and the support. Boron doping effectively modulates the support's band structure, enhancing both the charge transfer from the highest occupied molecular orbital of Pd1 atom to the support's lowest unoccupied state and the electron back-donation from the support's highest occupied state to the lowest unoccupied molecular orbital of Pd1. This balanced dual coupling minimizes net charge transfer, thereby stabilizing Pd1 atoms in a nearly zero-valent state. The FMO theory further consistently rationalizes the superior H2 activation kinetics and thermodynamics on electron-enriched Pd1/BCN, establishing it as a valuable framework for the rational design of SACs with optimized activity and stability.

Key words: Single-atom catalysts, Metal-support interaction, Frontier orbital theory, Stability, Hydrogenation reactions