| 金红石TiO2纳米团簇与铀酰相互作用的相对论密度泛函理论计算 | |
| Relativistic DFT Calculations of Interaction between Rutile TiO2 Nanoparticle Clusters and Uranyl Species | |
| 摘要: 采用全电子相对论密度泛函理论方法探索金红石型TiO2纳米团簇与铀酰的相互作用。考察金红石团簇模型（包括层数和表面积大小）变化对吸附铀形成复合物结构、吸附作用能等性质的影响，确定2层、表面积为1.1 nm×0.6 nm、包括63个原子的纳米团簇（标记为2L-Ti15）能够合理描述金红石纳米粒子性质的同时，还能节约计算资源。对2L-Ti15-[（UO2）（H2O）3]2+复合物计算表明，纳米团簇和铀酰存在共价键作用；优化得到U-Osurf键长0.233~0.238 nm，这一距离在已发现铀酰基配合物U-O距离范围内。在气相条件下，纳米团簇对铀酰吸附反应为放热过程（-3.02 eV）；考虑溶剂介质环境的影响，反应则需要吸收少许能量（0.16 eV）。U-Osurf键的能量分解发现，纳米团簇和铀酰的化学键作用为轨道相互作用主导的（占94%），它的静电吸引略大于Pauli排斥。基于电子密度的QTAIM（quantum theory of atoms in molecule）分析揭示，U-Osurf作用是介于离子和共价之间的配位键，其强度高于复合物中的U-OH2键作用，但比U=O键弱。波函数分析表明，来自纳米团簇的O（2p）贡献HOMO轨道，并混有σ（U=O）成键性质，而LUMO轨道则为Ti（3d）修饰的U（5f）性质，复合物HOMO-LUMO带隙为2.40 eV，相对吸附前的纳米团簇半导体粒子的3.35 eV变窄。从吸收光谱角度而言，复合物体系可能在可见光区域具有更强的捕光性能。 | |
| 关键词: 金红石TiO2纳米团簇 铀污染物 吸附作用本质 电子结构 相对论密度泛函理论 | |
| 基金项目: 国家自然科学基金（No.21671060，21273063）资助项目。 | |
| Abstract: The interaction between rutile TiO2 nanoparticle clusters (NPCs) and aquouranyl species have been examined using a relativistic functional theory (DFT). Effects of NPCs with various layers (1~4) and different surface areas on structural parameters of uranium adsorption complexes as well as adsorption interaction energies were investigated. It is found that the two-layered (2L) NPC (labeled as 2L-Ti15) with a surface area of 1.1 nm×0.6 nm and containing 63 atoms can reasonably stand for experimentally real TiO2 nanocrystallite. Moreover, the model is able to save computational resources. Calculations reveal a covalent bonding interaction in the 2L-Ti15-[(UO2)(H2O)3]2+ complex. The direct evidences include that the bond lengths of U-Osurf were optimized to be 0.233~0.238 nm, which fall well within the range of U-O distances of reported uranyl complexes. The process that the NPC adsorbs aquouranyl species is exothermic in the gas phase, releasing energy of -3.02 eV; the consideration of environment media of solution results in a slightly uphill process, requiring 0.16 eV energy. The energetic decomposition indicates that U-Osurf bonds are dominated by orbital interactions, accounting for 94%; other factors show a little effect, although electrostatic attraction is a little larger than Pauli repulsion. Electron density-based QTAIM (quantum theory of atoms in molecule) analyses unravel that the U-Osurf interaction is a dative bond per se, whose strength is stronger than that of U-OH2, but much weaker than that of U=Oyl. Inspection of wavefunction demonstrates that HOMO is contributed by O(2p) of NPC TiO2 mixed with a small amount of σ(U=O) bonding character, while LUMO is U(5f)-based character modified by Ti(3d). The HOMO-LUMO gap was calculated to be 2.40 eV, which much narrower than the one of NPC semiconductor (3.35 eV). From a point of view of absorption spectra, the complex system would present a visible light-harvesting capability. | |
| Keywords: rutile TiO2 nanoparticle clusters uranium contaminant adsorption interaction nature electronic structures relativistic DFT | |
| 投稿时间：2017-10-28 修订日期：2018-02-07 | |
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| 郑明,张红星,袁福龙,潘清江.金红石TiO2纳米团簇与铀酰相互作用的相对论密度泛函理论计算[J].无机化学学报,2018,34(5):874-882. | |
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