Du Shihu, Zhang Ziheng, Li Gang, Cheng Shibo, Kong Xiangtao, Li Lu, Yuan Qinqin, Xie Hua, Jiang Ling
State Key Laboratory of Chemical Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
School of Chemistry and Chemical Engineering, Shandong University Jinan 250100 China.
Chem Sci. 2025 Aug 20. doi: 10.1039/d5sc04467g.
Metal carbides hold significant potential as catalytic and functional materials. However, the absence of explicit directives hinders investigations of the reaction mode of metal carbide clusters. In this study, we employ size-specific photoelectron velocity-map imaging spectroscopy to explore the reactivity of metal tricarbon clusters MC (M = Os, Ir, Pt) in nitrogen activation. The experimental results reveal two competing modes of nitrogen activation: cleavage of the N[triple bond, length as m-dash]N bond with formation of a stable C-N bond, and chemisorption. IrC exhibits coexistence of dual nitrogen activation mechanisms, while OsC achieves nitrogen activation through cleavage of the N[triple bond, length as m-dash]N bond and PtC employs chemisorption-mediated activation of dinitrogen. Further theoretical analysis suggests that the activation of N by MC (M = Os, Ir, Pt) decreases as the 5d orbital energy of the metal atoms decreases. Additionally, the chemisorption mode becomes more dominant, consistent with the experimental results. These findings are promising for advancing nitrogen activation and have important implications for the development of related single-atom catalysts with isolated metal atoms dispersed on supports.
金属碳化物作为催化和功能材料具有巨大潜力。然而，缺乏明确的指导方针阻碍了对金属碳化物团簇反应模式的研究。在本研究中，我们采用尺寸特异性光电子速度映射成像光谱来探索金属三碳团簇MC（M = Os、Ir、Pt）在氮活化中的反应活性。实验结果揭示了两种相互竞争的氮活化模式：N≡N键的断裂并形成稳定的C-N键，以及化学吸附。IrC表现出双重氮活化机制的共存，而OsC通过N≡N键的断裂实现氮活化，PtC则采用化学吸附介导的双氮活化。进一步的理论分析表明，MC（M = Os、Ir、Pt）对N的活化随着金属原子5d轨道能量的降低而减弱。此外，化学吸附模式变得更加占主导地位，这与实验结果一致。这些发现对于推进氮活化具有重要意义，并对开发相关的单原子催化剂具有重要启示，其中孤立的金属原子分散在载体上。
