【作者】 刘佳；

【导师】 程世博；

【作者基本信息】 山东大学 ， 化学， 2025， 硕士

【摘要】 团簇是介于原子、分子和宏观物质之间的多核聚集体,是连接微观物质结构和宏观性质的关键桥梁。超原子作为团簇科学中的重要组成部分,因其可以模拟元素周期表中特定原子的性质成为研究的热点领域。功能化超原子构建是突破材料性能瓶颈的关键方向,其中磁性超原子通过原子级磁序调控推动高密度存储与量子器件发展,超卤素则凭借高电子亲和性成为催化体系与绿色合成的核心基元。同时,针对团簇催化领域中非贵金属催化剂性能内在限制的核心挑战,本文提出了非金属掺杂策略实现磁性超原子的高效设计方法,并发展定向外电场(OEEF)驱动的超卤素无损构建方法。同时,通过调控OEEF的参数,本文建立了吸附强度、反应能垒与OEEF参数的动态关联机制,为功能化超原子的设计及复杂催化反应中团簇的智能调控提供了理论框架与方法学支撑。本论文的内容和核心创新点体现在:(1)在团簇研究中,通过非金属原子掺杂来调控过渡金属团簇的磁性与光谱特性为开发新型超原子提供了关键的调控手段。本研究基于密度泛函理论(DFT),系统地研究了 Co4Pn(n=1-6)团簇的几何结构、稳定性、电子性质、磁性能和光谱特性。研究结果表明,除Co4P团簇外,其它团簇的基态结构均以Co4框架为基本结构单元,其中P原子优先占据由Co原子形成的三角形面上方的位点。所有团簇均表现出高磁矩特征,其磁性主要源于Co原子的d轨道。同时,Co4P4团簇具有高度对称的Td点群结构,通过键长、电荷分布及轨道特征分析发现团簇呈现由Co4四面体核与P4壳层组成的核壳构型,且其热力学稳定性已通过计算验证。分子轨道分析表明,Co4P4团簇具有明确的超原子轨道排布,具体的排布方式为1S2|1P6|2S2|1D10|2P6|1F14|3S2|2D8,其中两个单电子平行自旋地占据了近简并的超原子D轨道,这一发现为研究超原子的磁性机制提供了理论基础。此外,本研究还模拟了 Co4P4团簇的红外和拉曼光谱,为解释其电子和几何特性奠定了理论基础。这项研究为磁性超原子的设计及其光谱响应特性的可控制备提供了新视角。(2)基于DFT,本研究系统地研究了不同方向和强度的OEEF对Co4P4团簇的电子性质、小分子吸附及CO氧化反应的影响。计算结果表明,OEEF可将团簇的电子亲和能(EA)从非超卤素提升至超卤素的阈值,同时保持核壳结构、磁性和超原子轨道排布的稳定性。通过建立OEEF强度与EA值的多项式拟合方程,本研究实现了 EA值的非侵入式精确调控。值得注意的是,OEEF对电荷分布的定向调控效应与场强的变化有直接联系,这种定向性可能通过调控活性位点分布与反应能垒直接影响催化反应进程。为了明确OEEF对反应路径的作用机制,基于CO氧化模型,本研究揭示了 OEEF通过场强/方向调控CO/O2吸附与活化过程的机制,证实其可精准调控小分子吸附并实现活化/钝化态的可逆切换。进一步分析反应路径表明,OEEF对反应能垒呈现规律性的调制效应。总而言之,本研究提出了一种新型调控策略,为超原子的精准构建和高效催化剂的设计提供了新思路。更多还原

【Abstract】 Clusters are multinuclear aggregates between atoms,molecules and macroscopic substances,which are the critical bridges connecting the microscopic material structure and macroscopic properties.Superatoms,as an essential component in cluster science,have become an exciting area of research for their ability to mimic the properties of specific atoms in periodic table of elements.Functionalized superatoms are key to overcoming material performance bottlenecks:magnetic superatoms advance high-density storage and quantum devices via atomic-level magnetic ordering,while superhalogens drive catalytic systems and green synthesis with high electron affinity(EA).Meanwhile,to address the fundamental challenge of inherent performance limitations of non-precious metal clusters catalysts,in this paper,we employ a non-metallic doping strategy to realize the efficient design of magnetic superatoms,and also develop a non-destructive superhalogen construction technique driven by oriented external electric field(OEEF).In addition,through regulating the parameters of OEEF,we have established a dynamic correlation mechanism between adsorption strength,reaction barrier and OEEF,providing a theoretical framework and methodological foundation for the design of functional superatoms and the intelligent regulation of clusters in complex catalytic reactions.The key contributions and novel aspects of this study can be summarized as:(1)Tailoring the magnetic properties and spectroscopic characteristics of transition metal(TM)clusters by doping non-metallic atoms is essential for the development of novel superatoms.Here,we employed DFT to investigate the geometry,stability,electronic structure,and magnetic properties of the Co4Pn(n=1-6)clusters.Our findings revealed that,except for Co4P,the clusters adopted a structure where phosphorus(P)atoms were added to the triangular faces of a Co4 core.These clusters exhibit high magnetic moments,primarily arising from the d-orbitals of Co atoms.Notably,Co4P4 adopts a highly symmetric Td point group structure,characterized by a core-shell configuration composed of Co4 and P4 tetrahedra.This structure,which represents the smallest cluster-based architecture,was confirmed through distance,charge,and orbital analyses,and is thermodynamically stable.Molecular orbital analysis uncovers a well-defined superatomic orbital arrangement of 1S2|1P6|2S2|1D10|2P6|1F14|3S2|2D8 with two electrons in parallel spin arrangements in the D orbitals,providing insights into the magnetic behavior of these superatoms.Furthermore,the infrared and Raman spectra of Co4P4 were further analyzed to establish a theoretical foundation for interpreting its electronic and geometrical properties.This study offers new perspectives on designing magnetic superatoms and tailoring their spectral response functions for targeted applications.(2)Based on the DFT,we investigated the effects of different orientations and strengths of OEEF on the electronic properties,the adsorption of small molecules,and the CO oxidation reaction of Co4P4.The results showed that OEEF enables precise raising the EA from the nonsuperhalogens to the superhalogens defining threshold,while the core-shell structure,magnetic properties,and superatomic orbital arrangement remain stable during the regulation process.Non-invasive and precise regulation of EA were achieved by establishing a polynomial fitting equation between OEEF strengths and EAs.Notably,the oriented modulation effect of OEEF on charge distribution is directly linked to the change in field strength,and this orientation may directly affect the catalytic reaction process by modulating the distribution of active sites and reaction energy barriers.To clarify OEEF’s mechanistic control over reaction pathways,this study employs a CO oxidation model to reveal field strength/oriented-dependent regulation of CO/O2 adsorption-activation processes,demonstrating precision in molecular adsorption modulation and reversible active/passive state switching.Further analysis showed that OEEF exhibits a regular modulation effect on the energy barrier.In summary,we propose a new regulatory strategy to provide new ideas for the construction of superatoms and the design of efficient catalysts.更多还原