CO分子在Co(0001)表面吸附的第一性原理研究

应用第一性原理对CO分子在Co(0001)表面( squar3× squar3)R30°−CO吸附结构进行不同形式的密度泛函计算研究. 结果表明：吸附能修正前,仅RPBE泛函预测CO顶位吸附;而修正后PW91、PBE和PKZB泛函结果也表明CO分子Top顶位吸附最稳定,与实验结果一致.对于吸附几何结构、吸附前后体系功函、C-O伸缩振动频率和CO分子态密度分布,所有泛函给出一致的结果,且与已有实验结果符合.     

CO在Pu(100)表面吸附的研究

采用密度泛函理论(DFT)研究了CO分子在Pu (100)面上的吸附. 计算结果表明：CO在Pu (100)表面的C端吸附比O端吸附更为有利,属于强化学吸附. CO吸附态的稳定性为穴位倾斜>穴位垂直>桥位>顶位. CO分子与表面Pu原子的相互作用主要源于CO分子的杂化轨道和Pu原子的杂化轨道的贡献. 穴位倾斜吸附的CO分子的离解能垒较小(0.280eV),表明在较低温度下,CO分子在Pu (100)表面会发生离解吸附,离解的C,O原子将占据能量最低的穴位. 关键词： 密度泛函理论 Pu (100) CO 分子和离解吸附     

CO在Pu(100)表面吸附的研究

采用密度泛函理论(DFT)研究了CO分子在Pu (100)面上的吸附. 计算结果表明：CO在Pu (100)表面的C端吸附比O端吸附更为有利，属于强化学吸附. CO吸附态的稳定性为穴位倾斜>穴位垂直>桥位>顶位. CO分子与表面Pu原子的相互作用主要源于CO分子的杂化轨道和Pu原子的杂化轨道的贡献. 穴位倾斜吸附的CO分子的离解能垒较小(0.280eV)，表明在较低温度下，CO分子在Pu (100)表面会发生离解吸附，离解的C，O原子将占据能量最低的穴位.     

气体分子在类石墨烯材料负载单个金属原子表面的吸附特性

采用密度泛函理论方法研究了不同种类和数量的气体小分子在类石墨烯材料(graphenylene)衬底支撑的金属原子(M=Co, Mo和Pd, gra-M)表面的吸附特性,系统地分析了吸附不同数量的NO和CO分子的稳定构型,吸附能,电荷转移量以及引起的体系电子结构和磁性变化.研究结果表明:1) NO、CO气体小分子的稳定吸附位在金属原子顶位,吸附物与衬底间的电荷转移量表明负载不同的金属原子能够有效地调制类石墨烯材料的气敏特性;2)单个和两个气体分子吸附能够引起gra-M体系的自旋电荷密度分布发生变化,进而使得气体吸附体系表现出不同磁矩大小.     

不同覆盖度下丙硫醇在Au(111)面吸附的理论研究

采用基于密度泛函理论的第一性原理方法研究了丙烷硫醇 (C₃H₇SH)在Au(111)面五种覆盖度(1/16, 2/16, 3/16, 4/16, 1/3) 下的未解离和解离吸附的结构、能量和吸附性质. 发现丙烷硫醇的倾斜角和吸附能均受覆盖度影响, 计算结果显示丙烷硫醇的倾斜角随着覆盖度的增大减小了6°–10°, 吸附能随覆盖度的增大减小了0.21 eV. 特别针对饱和覆盖度, 研究了三种可能的表面结构: (2√3×2√3 ight)R30°, 2√3×3和(3×3). 发现S–H键未解离时三种表面结构的吸附构型和吸附能基本一致; S–H键解离后, (2√3×2√3 ight)R30°和2√3×3结构的吸附能比以(3×3)结构的吸附能约高0.05–0.07 eV, 说明C₃H₇S在Au(111)面吸附时, 倾向于形成(2√3×2√3 ight)R30°和2√3×3结构. 此外, 采用DFT-D2方法对饱和覆盖度下C₃H₇SH分子在Au(111)面的吸附进行了范德华修正, 结果显示分子间相互作用使吸附物和Au表面的距离减小, 该相互作用对吸附能的修正值为0.53 eV, 修正后结果与实验结果接近. 关键词： 第一性原理 覆盖度 表面结构 范德华力     

金属和非金属原子间协同效应调控气体小分子的吸附特性研究

采用基于密度泛函理论方法系统地研究了单个NO和CO小分子在非金属(B和N)与金属Ni原子共掺杂石墨烯(Bx-Ny-gra-Ni,x+y=0,1,2,3)表面的吸附特性,分析了吸附气体小分子的几何结构,吸附能,电荷转移量以及引起体系磁性变化等情况.研究结果表明：NO和CO倾向于吸附在Ni原子的顶位,B和N掺杂原子的数量和比例能够有效地调制小分子的吸附强度;与吸附的CO分子相比,Bx-Ny-gra-Ni表面吸附的NO分子能获得较多的电荷,进而表现出高的稳定性.此外,利用吸附的气体小分子与衬底间相互作用强度和灵敏性的差异、以及引起反应衬底的磁性变化将为设计石墨烯基气敏、催化和电子器件提供重要参考.     

气体分子在Co-BN表面吸附的第一性原理研究

采用包含色散力校正的密度泛函理论(DFT-D)方法系统地研究了气体分子(O2, H2, NO, CO, CO2, SO2, H2S, H2O)在Co掺杂单层BN(Co-BN)表面的吸附, 分析了吸附小分子的几何结构, 吸附能, 电荷转移等情况. 结果表明: 1) CO等气体分子主要吸附在Co及其近邻六元环的顶位, 吸附结构的电荷转移表明掺杂原子Co对BN衬底的气敏特性有较好的调制作用; 2) 在Co-BN表面吸附的O2和CO较易被活化, 表明Co-BN可能是一种对CO氧化有较好催化活性的新型催化材料.     

第一性原理分析二氧化碳在CaO(100)表面的吸附性能

运用广义梯度密度泛函理论（GGA-PW91）结合周期平板模型方法,研究了CO2分子分别在1×1×1和2×2×1CaO(100)超晶胞面最稳定位的吸附行为。结果表明：CaO(100)表面的Osurf原子为CO2分子的有效吸附位,能够和CO2分子形成稳定吸附键C-Osurf, 其吸附能为0.858 eV。在吸附前后C和Osurf原子的价电子组态分别由2s0.892p2.47和2s1.842p4.99变化为2s0.682p2.33和2s1.902p5.17,而且在CO2分子中的O2s原子与Surface层的Casub4s原子间存在相互作用。考察了多个CO2分子在2×2×1 CaO(100)表面吸附时存在分子间相互排斥作用,发现当四个CO2分子吸附到2×2×1CaO(100)超晶胞面时,排斥能为1.76 eV,不利于CO2分子的吸附。     

第一性原理分析二氧化碳在CaO(100)表面的吸附性能

运用广义梯度密度泛函理论（GGA-PW91）结合周期平板模型方法,研究了CO2分子分别在1×1×1和2×2×1CaO(100)超晶胞面最稳定位的吸附行为。结果表明：CaO(100)表面的Osurf原子为CO2分子的有效吸附位,能够和CO2分子形成稳定吸附键C-Osurf, 其吸附能为0.858 eV。在吸附前后C和Osurf原子的价电子组态分别由2s0.892p2.47和2s1.842p4.99变化为2s0.682p2.33和2s1.902p5.17,而且在CO2分子中的O2s原子与Surface层的Casub4s原子间存在相互作用。考察了多个CO2分子在2×2×1 CaO(100)表面吸附时存在分子间相互排斥作用,发现当四个CO2分子吸附到2×2×1CaO(100)超晶胞面时,排斥能为1.76 eV,不利于CO2分子的吸附。     

原子分子在Ni(100)表面吸附的第一性原理研究

本文采用密度泛函理论,结合周期性平板模型,通过对原子H、N、O、S和C,分子CO、N2、NH3、NO,以及自由基CH3、CH、CH2、OH在Ni(100)表面吸附的研究,比较了它们的吸附能,稳定吸附位点,吸附结构及扩散能垒等信息.这些吸附质与表面结合能力从小到大依次是N2NH3COCH3NOHOHCH2CNSONCHC.在所有的原子中,O原子倾向于吸附在桥位,而其余的原子则倾向于吸附在空位.除N2之外的分子吸附物(CO、NO、NH3),最佳吸附位点均为四重空位,而N2的最稳定吸附位置为顶位.对于自由基吸附物(CH、CH2、CN、OH)而言,它们倾向于吸附在四重空位,而CH3则稳定吸附在桥位.     

CO adsorption on the Cu(1 1 1) surface: A density functional study

The adsorption of CO on the Cu(1 1 1) surface has been studied with ab initio density functional theory. The adsorbate-metal system was analyzed with the local density approximation, the gradient corrected functional of Perdew and Wang and the B3LYP hybrid functional, for comparison. A slab model was used for the pattern at a coverage of 1/3. The local density approximation and the gradient corrected functional give the fcc site as the favorable adsorption site. In contrast, the B3LYP functional results in the preference of the top site, in agreement with the experiment. These results confirm the suggested explanation for the failure of standard functionals, based on the position of the highest occupied and lowest unoccupied molecular orbital. The results of total energy calculations are presented, together with projected densities of states and Mulliken populations. In addition, the basis set superposition error is discussed for CO/Cu(1 1 1) and for CO/Pt(1 1 1).     

A density functional theory study on the adsorption of CO and O₂ on Cu-terminated Cu₂O（111） surface

The adsorptions of CO and O2 molecules individually on the stoichiometric Cu-terminated Cu2O(111) surface are investigated by first-principles calculations on the basis of the density functional theory.The calculated results indicate that the CO molecule preferably coordinates to the Cu2 site through its C atom with an adsorption energy of -1.69 eV,whereas the O2 molecule is most stably adsorbed in a tilt type with one O atom coordinating to the Cu2 site and the other O atom coordinating to the Cu1 site,and has an adsorption energy of -1.97 eV.From the analysis of density of states,it is observed that Cu 3d transfers electrons to 2π orbital of the CO molecule and the highest occupied 5σ orbital of the CO molecule transfers electrons to the substrate.The sharp band of Cu 4s is delocalized when compared to that before the CO molecule adsorption,and overlaps substantially with bands of the adsorbed CO molecule.There is a broadening of the 2π orbital of the O2 molecule because of its overlapping with the Cu 3d orbital,indicating that strong 3d-2π interactions are involved in the chemisorption of the O2 molecule on the surface.     

Adsorption of CO on the O2 pre-adsorbed LaFeO3 (0 1 0) surface: A density functional theory study

The adsorption of CO molecule on the O₂ pre-adsorbed LaFeO₃ (0 1 0) surface has been investigated using a density functional theory calculation. The calculated results show that the most appropriate reaction occurs between the CO and the pre-adsorbed O₂. After CO adsorption, the bonding mechanism between Fe site and the pre-adsorbed O₂ is not modified, and the HOMO–LUMO energy gap of the M1 mode is narrowed, which is caused by the redistribution of electron density in the surface.     

第一性原理研究CO在Cu(110)表面的吸附

本文采用基于密度泛函理论的第一性原理方法, 并同时考虑范德华力的作用, 计算并分析了CO在Cu(110)表面的吸附情况. 结果表明: 1) CO在两个表面Cu原子的短桥位位置吸附最强, 吸附能为1.28 eV. 第二稳定吸附位置为表面Cu原子的顶位, 吸附能为1.23 eV. CO在其他两个位置, 表面两个Cu的长桥位和表面四个Cu的中心位的吸附要弱一些, 约为0.86 eV 和 0.83 eV. 2) 在Cu表面吸附的CO的C-O键长有部分拉长, 这与较强的吸附能和电荷转移相应. 3) 电荷分析表明所有吸附的CO整体上从衬底上面获得部分电荷, 约为0.2 个电荷.     

第一性原理研究CO在Cu(110)表面的吸附

本文采用基于密度泛函理论的第一性原理方法,并同时考虑范德华力的作用,计算并分析了CO在Cu(110)表面的吸附情况.结果表明:1)CO在两个表面Cu原子的短桥位位置吸附最强,吸附能为1.28 e V.第二稳定吸附位置为表面Cu原子的顶位,吸附能为1.23 e V.CO在其他两个位置,表面两个Cu的长桥位和表面四个Cu的中心位的吸附要弱一些,约为0.86 e V和0.83 e V.2)在Cu表面吸附的CO的C-O键长有部分拉长,这与较强的吸附能和电荷转移相应.3)电荷分析表明所有吸附的CO整体上从衬底上面获得部分电荷,约为0.2个电荷.     

General insight into CO oxidation: a density functional theory study of the reaction mechanism on platinum oxides

CO oxidation on PtO2(110) has been studied using density functional theory calculations. Four possible reaction mechanisms were investigated and the most feasible one is the following: (i) the O at the bridge site of PtO2(110) reacts with CO on the coordinatively unsaturated site (CUS) with a negligible barrier; (ii) O2 adsorbs on the bridge site and then interacts with CO on the CUS to form an OO-CO complex; (iii) the bond of O-OCO breaks to produce CO2 with a small barrier (0.01 eV). The CO oxidation mechanisms on metals and metal oxides are rationalized by a simple model: The O-surface bonding determines the reactivity on surfaces; it also determines whether the atomic or molecular mechanism is preferred. The reactivity on metal oxides is further found to be related to the 3rd ionization energy of the metal atom.     

A density functional theory study on the adsorption of CO and O2 on Cu-terminated Cu2O （111） surface

The adsorptions of CO and 02 molecules individually on the stoichiometric Cu-terminatcd Cu20 （111） surface are investigated by first-principles calculations on the basis of the density functional theory. The calculated results indicate that the CO molecule preferably coordinates to the Cu2 site through its C atom with an adsorption energy of-1.69 eV, whereas the 02 molecule is most stably adsorbed in a tilt type with one O atom coordinating to the Cu2 site and the other O atom coordinating to the Cul site, and has an adsorption energy of -1.97 eV. From the analysis of density of states, it is observed that Cu 3d transfers electrons to 2π orbital of the CO molecule and the highest occupied 5σ orbital of the CO molecule transfers electrons to the substrate. The sharp band of Cu 4s is delocalized when compared to that before the CO molecule adsorption, and overlaps substantially with bands of the adsorbed CO molecule. There is a broadening of the 2π orbital of the 02 molecule because of its overlapping with the Cu 3d orbital, indicating that strong 3d-2π interactions are involved in the chemisorption of the 02 molecule on the surface.     

CO on Pd(110): determination of the optimal adsorption site

We present ab initio pseudo-potential plane-wave total-energy calculations for the geometric and electronic structure of the CO-covered Pd(110) surface. Our calculations were performed within the local-density approximation (LDA) of density functional theory (DFT). There has been some controversy as to whether CO prefers to adsorb at a bridge or on-top site when exposed to Pd(110). Total energy calculations for a CO monolayer adsorbed at the on-top and bridge adsorption sites revealed the bridge site adsorption to be favored by 0.59 eV per CO molecule. The preferential adsorption of CO to the bridge site was further corroborated by our band-structure calculations, with only the bridge site results being in good agreement with recent inverse photoemission experiments.     

锰基金属有机框架材料{[Mn2(ina)4(H2O)2]·2EtOH}n的电子结构、磁性和吸附性能的理论研究

本文采用密度泛函理论研究了锰基金属有机框架(MOF)材料{[Mn2(ina)4(H2O)2]·2EtOH}n的电子性质, 磁学性质及吸附二氧化碳的性能,结果表明: 该MOF材料是一种反铁磁耦合材料, 其高的CO2结合亲和力主要归因于CO2 (作为Lewis碱的氧孤对电子)到不饱和金属位点(Lewis酸)的较高电荷转移。本文也对实验中报道的对CO2/N2烟气混合物有高选择性CO2吸附能力进行了验证,理论计算值与实验值有着很好的一致性。