Interaction of a transition metal atom with intrinsic defects in single-walled carbon nanotubes

Interaction of a transition metal atom with defects in single-walled carbon nanotubes (SWNTs) were investigated through density functional theory calculations. For three kinds of intrinsic defects (single vacancies, double vacancies and Stone-Wales defects) in (5,5) armchair and (10,0) zigzag SWNTs, stable configurations were analyzed. The orientation of the specific bonds of the defects is related to the most stable configuration among several possible configurations. The stable adsorption sites and binding energies of a Ni atom on three intrinsic defects were calculated and compared to those on perfect side walls. All defects enhance Ni adsorption, and the single vacancy shows the most exothermic binding. These results shed light on the nature of the interaction of the transition metal with defects in SWNT, an important topic to the many aspects of carbon nanotubes interacting with transition metals. Particularly, this is useful for the fabrication of nanosized transition metal particles supported on carbon nanotubes.     

Adsorption of spillover hydrogen atoms on single-wall carbon nanotubes

Spillover of hydrogen on nanostructured carbons is a phenomenon that is critical to understand in order to produce efficient hydrogen storage adsorbents for fuel cell applications. The spillover and interaction of atomic hydrogen with single-walled carbon nanotubes (SWNTs) is the focus of this combined theoretical and experimental work. To understand the spillover mechanism, very low occupancies (i.e., 1 and 2 H atoms adsorbed) on (5,0), (7,0), (9,0) zigzag (semiconducting) SWNTs and a (5,5) armchair (metallic) SWNT, with corresponding diameters of 3.9, 5.5, 7.0, and 6.8 A, were investigated. The adsorption binding energy of H atoms depends on H occupancy, tube diameter, and helicity (or chirality), as well as endohedral (interior) vs exohedral (exterior) binding. Exohedral binding energies are substantially higher than endohedral binding energies due to easier sp(2)-sp(3) transition in hybridization of carbon on exterior walls upon binding. A binding energy as low as -8.9 kcal/mol is obtained for 2H atoms on the exterior wall of a (5, 0) SWNT. The binding energies of H atoms on the metallic SWNT are significantly weaker (about 23 kcal/mol weaker) than that on the semiconductor SWNT, for both endohedral and exohedral adsorption. The binding energy is generally higher on SWNTs of larger diameters, while its dependence on H occupancy is relatively weak except at very low occupancies. Experimental results at 298 K and for pressures up to 10 MPa with a carbon-bridged composite material containing SWNTs demonstrate the presence of multiple adsorption sites based on desorption hysteresis for the spiltover H on SWNTs, and the experimental results were in qualitative agreement with the molecular orbital calculation results.     

CO2 adsorption by nitrogen-doped carbon nanotubes predicted by density-functional theory with dispersion-correcting potentials

The interaction of CO(2) to the interior and exterior walls of pristine and nitrogen-doped single-walled carbon nanotubes (SWNT) has been studied using density-functional theory with dispersion-correcting potentials (DCPs). Our calculations predict Gibbs energies of binding between SWNT and CO(2) of up to 9.1 kcal mol(-1), with strongest binding observed for a zigzag [10,0] nanotube, compared to armchair [6,6] (8.3 kcal mol(-1)) and chiral [8,4] (7.0 kcal mol(-1)). Doping of the [10,0] tube with nitrogen increases the Gibbs energies of binding of CO(2) by ca. 3 kcal mol(-1), but slightly reduced binding is found when [6,6] and [8,4] SWNT are doped in similar fashion. The Gibbs energy of binding of CO(2) to the exterior of the tubes is quite small compared to the binding that occurs inside the tubes. These findings suggest that the zigzag SWNT show greater promise as a means of CO(2) gas-capture.     

Pd6簇与H2分子相互作用的密度泛函理论研究

通过相对论有效核势密度泛函理论计算,优化了Pd6(H)2和Pd6(H)4等簇的平衡几何结构,预测了氢分子在Pd6簇表面上的吸附行为与活化解离性质.计算结果表明,单态的Pd6簇可以活化两个氢分子;第一个H2和第二个H2吸附解离过程速率决定步骤的能垒分别是66.4和24.5kJ/mol、在形成的分子氢配合物Pd6(H2)和Pd（H)2H2中,H2主要作为给电子配体.在最稳定的二氢簇合物Pd6(H)2中,H倾向与3个Pd相互作用,形成面位氢的多核成键吸附方式.     

The direct observation of 2H‐DPP metalation on Pd(111) and Cu/Pd(111) surface

The metalation behaviors of 5,15‐diphenylporphyrin (2H‐DPP) on Pd(111) and Cu/Pd(111) have been investigated using scanning tunneling microscopy and density functional calculations. We show that 2H‐DPP molecules deposited on Pd(111) surface form Pd‐DPP with a proportion of about 75% already at room temperature (RT). This is in contrast to non‐metalation adsorption of 2H‐DPP on Cu–Pd alloy at RT. Annealing to 323 K facilitates the metalation of 2H‐DPP on Cu–Pd alloy island. The comparison of the results indicates that the metalation of 2H‐DPP calls for both enough surface free energy of approaching N? H bond and enough reactivity of breaking N? H bond. Copyright © 2016 John Wiley & Sons, Ltd.     

Density Functional Theory Study of MoO3 Molecule Encapsulated inside Single-walled Carbon Nanotubes~

The binding energies, geometric structures and electronic properties of molybdenum trioxide (MoO3) molecule encapsulated inside (8,0), (9,0), (10,0) and (14,0) single-walled carbon nanotubes (SWNTs) have been investigated using density functional theory (DFT) method. Due to curvature effect, the calculated binding energy values are different, the variation of which indicated that the stability of MoO3 /SWNT systems increases with increasing the radius of SWNTs. At the same time, owing to the presence of MoO3 molecule, the band gap of MoO3 /SWNTs systems decreases. The analysis of density of states (DOS) reveals hybridization between C-2p and Mo-4d and between C-2p and O-2p orbitals near the Fermi level, which results in electron transfer from SWNTs to MoO3 molecule. The present computations suggest that electronic properties of SWNTs can be modified by doping MoO3 molecule.     

Phthalocyanine-pyrene conjugates: a powerful approach toward carbon nanotube solar cells

In the present work, a new family of pyrene (Py)-substituted phthalocyanines (Pcs), i.e., ZnPc-Py and H(2)Pc-Py, were designed, synthesized, and probed in light of their spectroscopic properties as well as their interactions with single-wall carbon nanotubes (SWNTs). The pyrene units provide the means for non-covalent functionalization of SWNTs via π-π interactions. Such a versatile approach ensures that the electronic properties of SWNTs are not impacted by the chemical modification of the carbon skeleton. The characterization of ZnPc-Py/SWNT and H(2)Pc-Py/SWNT has been performed in suspension and in thin films by means of different spectroscopic and photoelectrochemical techniques. Transient absorption experiments reveal photoinduced electron transfer between the photoactive components. ZnPc-Py/SWNT and H(2)Pc-Py/SWNT have been integrated into photoactive electrodes, revealing stable and reproducible photocurrents with monochromatic internal photoconversion efficiency values for H(2)Pc-Py/SWNT as large as 15 and 23% without and with an applied bias of +0.1 V.     

Rheological, thermal, and mechanical characterizations of polystyrene/single-walled carbon nanotube composites

For preparation of polystyrene (PS) composites, a polymeric dispersant, pyrene-capped polystyrene (PyPS), was applied for noncovalent functionalization of single-walled carbon nanotubes (SWNTs) to improve both dispersion quality and PS–SWNT interfacial interactions. To demonstrate the critical role of PyPS, the composites with the absence of PyPS (PS/SWNT) were also prepared for comparison. Rheological studies suggest that addition of SWNTs, particularly of PyPS-functionalized SWNTs, suppresses significantly large-scale relaxation of PS chains but has little effect on their short-range dynamics. Relative to PS, moderately improved thermal and mechanical properties took place on the composites with either pristine or PyPS-functionalized SWNTs. The PS/PyPS/SWNT composite usually presents better performance than the PS/SWNT one at a fixed SWNT content.     

复合半导体负载金属材料光催化性能研究

CO₂和烃类光催化直接合成烃类氧化物在合成化学、碳资源利用和环境保护等方面均有重大意义。用溶胶-凝胶和浸渍-还原相结合的方法制得M/V₂O₅-TiO₂(M=Pd、Cu、Ni和Ag)光催化剂。利用XRD、TPR、IR、TPD、UV-Vis DRS和光反应器等技术研究了负载金属复合半导体的物相结构、吸附性能、光吸收性能和光催化反应性能。结果表明：金属负载在复合半导体上延迟了TiO₂由锐钛矿向金红石相的转化,增强了V与载体TiO₂的相互作用,使TiO₂光吸收限发生蓝移,对可见光部分的吸收明显增加,拓宽了催化剂的光响应范围;材料吸光性能强弱顺序Pd/V₂O₅-TiO₂ >Cu/V₂O₅-TiO₂ >Ag/V₂O₅-TiO₂>Ni/V₂O₅-TiO₂;材料的吸附性能及反应物的吸附态是反应发生的关键,CO₂在Ag/V₂O₅-TiO₂表面无法形成卧式吸附态,没有目的产物甲基丙烯酸(MAA)生成,光量子效率低;光吸收性能较好的Pd/V₂O₅-TiO₂对CO₂吸附能力过强,卧式吸附态脱附温度高,光催化效率不高;Cu/V₂O₅-TiO₂对CO₂吸附能力适中,CO₂与C₃H₆脱附温度较接近,实现了“光-表面-热”的协同作用,光量子效率最高,达15.1%。     

Encapsulation of carbon chain molecules in single-walled carbon nanotubes

The vacuum space inside carbon nanotubes offers interesting possibilities for the inclusion, transportation, and functionalization of foreign molecules. Using first-principles density functional calculations, we show that linear carbon-based chain molecules, namely, polyynes (C(m)H(2), m = 4, 6, 10) and the dehydrogenated forms C(10)H and C(10), as well as hexane (C(6)H(14)), can be spontaneously encapsulated in open-ended single-walled carbon nanotubes (SWNTs) with edges that have dangling bonds or that are terminated with hydrogen atoms, as if they were drawn into a vacuum cleaner. The energy gains when C(10)H(2), C(10)H, C(10), C(6)H(2), C(4)H(2), and C(6)H(14) are encapsulated inside a (10,0) zigzag-shaped SWNT are 1.48, 2.04, 2.18, 1.05, 0.55, and 1.48 eV, respectively. When these molecules come inside a much wider (10,10) armchair SWNT along the tube axis, they experience neither an energy gain nor an energy barrier. They experience an energy gain when they approach the tube walls inside. Three hexane molecules can be encapsulated parallel to each other (i.e., nested) inside a (10,10) SWNT, and their energy gain is 1.98 eV. Three hexane molecules can exhibit a rotary motion. One reason for the stability of carbon chain molecules inside SWNTs is the large area of weak wave function overlap. Another reason concerns molecular dependence, that is, the quadrupole-quadrupole interaction in the case of the polyynes and electron charge transfer from the SWNT in the case of the dehydrogenated forms. The very flat potential surface inside an SWNT suggests that friction is quite low, and the space inside SWNTs serves as an ideal environment for the molecular transport of carbon chain molecules. The present theoretical results are certainly consistent with recent experimental results. Moreover, the encapsulation of C(10) makes an SWNT a (purely carbon-made) p-type acceptor. Another interesting possibility associated with the present system is the direction-controlled transport of C(10)H inside an SWNT under an external field. Because C(10)H has an electric dipole moment, it is expected to move under a gradient electric field. Finally, we derive the entropies of linear chain molecules inside and outside an open-ended SWNT to discuss the stability of including linear chain molecules inside an SWNT at finite temperatures.     

Pd Loaded NiCo Hydroxides for Biomass Electrooxidation: Understanding the Synergistic Effect of Proton Deintercalation and Adsorption Kinetics

The key issue in the 5-hydroxymethylfurfural oxidation reaction (HMFOR) is to understand the synergistic mechanism involving the protons deintercalation of catalyst and the adsorption of the substrate. In this study, a Pd/NiCo catalyst was fabricated by modifying Pd clusters onto a Co-doped Ni(OH)₂ support, in which the introduction of Co induced lattice distortion and optimized the energy band structure of Ni sites, while the Pd clusters with an average size of 1.96 nm exhibited electronic interactions with NiCo support, resulting in electron transfer from Pd to Ni sites. The resulting Pd/NiCo exhibited low onset potential of 1.32 V and achieved a current density of 50 mA/cm² at only 1.38 V. Compared to unmodified Ni(OH)₂, the Pd/NiCo achieved an 8.3-fold increase in peak current density. DFT calculations and in situ XAFS revealed that the Co sites affected the conformation and band structure of neighboring Ni sites through CoO₆ octahedral distortion, reducing the proton deintercalation potential of Pd/NiCo and promoting the production of Ni³⁺−O active species accordingly. The involvement of Pd decreased the electronic transfer impedance, and thereby accelerated Ni³⁺−O formation. Moreover, the Pd clusters enhanced the adsorption of HMF through orbital hybridization, kinetically promoting the contact and reaction of HMF with Ni³⁺−O.     

Simulation of adsorption of DNA on carbon nanotubes

We report molecular dynamics simulations of DNA adsorption on a single-walled carbon nanotube (SWNT) in an aqueous environment. We have modeled a DNA segment with 12 base pairs (Dickerson dodecamer) and a (8,8) SWNT in water, with counterions to maintain total charge neutrality. Simulations show that DNA binds to the external surface of an uncharged or positively charged SWNT on a time scale of a few hundred picoseconds. The hydrophobic end groups of DNA are attracted to the hydrophobic SWNT surface of uncharged SWNTs, while the hydrophilic backbone of DNA does not bind to the uncharged SWNT. The binding mode of DNA to charged SWNTs is qualitatively different from uncharged SWNTs. The phosphodiester groups of the DNA backbone are attracted to a positively charged SWNT surface while DNA does not adsorb on negatively charged SWNTs. There is no evidence for canonical double-stranded DNA wrapping around either charged or uncharged SWNTs on the very short time scales of the simulations. The adsorption process appears to have negligible effect on the internal stacking structure of the DNA molecule but significantly affects the A to B form conversion of A-DNA. The adsorption of A-DNA onto an uncharged SWNT inhibits the complete relaxation of A-DNA to B-DNA within the time scale of the simulations. In contrast, binding of the A-DNA onto a positively charged SWNT may promote slightly the A to B conversion.     

A Computational Study of a Single‐Walled Carbon‐Nanotube‐Based Ultrafast High‐Capacity Aluminum Battery

Exploring suitable electrode materials is a fundamental step toward developing Al batteries with enhanced performance. In this work, we explore using density functional theory calculations the feasibility of single‐walled carbon nanotubes (SWNTs) as a cathode material for Al batteries. Carbon nanotubes with hollow structures and large surface area are able to overcome the difficulty of activating the opening of interlayer spaces as observed in graphite electrode during the first intercalation cycle. Our results show that AlCl₄ binds strongly with the SWNT to result in an energetically and thermally stable AlCl₄‐adsorbed SWNT system. Diffusion calculations show that the SWNT system allows ultrafast diffusion of AlCl₄ with a more favorable inner surface diffusion than outer surface diffusion. Our charge‐density difference and Bader atomic charge analysis confirm the oxidation of SWNT upon adsorption of AlCl₄, which shows a similar behavior to the previously studied graphite cathode. The average open‐circuit voltage and AlCl₄ storage capacity increases with increasing SWNT diameter and can be as high as 1.96 V and 275 mA h g⁻¹ in (25,25) SWNT relative to graphite (70 mA h g⁻¹). All of these properties show that SWNTs are a potential cathode material for high‐performance Al batteries and should be explored further.     

Stable containment of radionuclides on the nanoscale by cut single-wall carbon nanotubes

The physisorption of radiolabeled (125)I(-) ions from aqueous solution and the Brunauer-Emmett-Teller (BET) surface areas of various carbonaceous materials [HiPco single-wall carbon nanotubes (SWNTs), F-SWNTs, cut SWNTs, charcoal, graphite, F-graphite and C(60)] have been measured and compared. By far, cut SWNTs (mainly 20-50 nm lengths) displayed the largest surface area of the materials (1180 m(2).g(-1)), being approximately double that of uncut SWNT and charcoal. At low concentrations of (125)I(-), nearly all of the (125)I(-) was adsorbed from aqueous solution within 1 min at room temperature by the cut SWNTs, uncut SWNTs, and charcoal; the other materials showed much less adsorption under the same conditions. Once adsorbed, the (125)I(-) wash-off rate by pure water was highly variable but was especially slow for cut SWNTs (t(1/2) approximately 2720 h) compared to the other materials; wash-off of (125)I(-) by an aqueous H(2)O(2) solution was even slower (t(1/2) approximately 14 300 h). Taken together, these data demonstrate the greatly increased surface area and dramatically enhanced retention properties of cut SWNTs over uncut SWNTs.     

Impurity effects on small Pd clusters: a relativistic density functional study of Pd4X, X = H, C, O

We carried out relativistic density functional calculations to investigate systematically the effect of main group element impurities H, C, and O on a Pd4 cluster. We determined a bridging coordination for Pd4H as most stable, whereas several other local minima are energetically close. The interaction of C with Pd4 is strong enough to restructure the cluster, resulting in two Pd2 units bridged by 4-fold coordinated C, but other isomers are again almost degenerate. Nearly degenerate isomers of Pd4O exhibit 2- and 3-fold coordination of O. In the most stable structures, the binding energies of the impurities, 295 kJ/mol for Pd4H, 655 kJ/mol for Pd4C, and 367 kJ/mol for Pd4O, are large enough to allow bond breaking of common small molecules when they interact with an ensemble of Pd4 clusters. Interestingly, the noteworthy relativistic effect on the properties of Pd4 also affects the interaction with impurity atoms. Comparison with other metals reveals similarities with Ni4X and differences from Ir4H, Ir4C, and Pt4H.     

氢和硫原子在Pd、Au和Cu及PdAu、PdCu合金(111)表面吸附的密度泛函研究

用密度泛函理论研究了氢和硫原子在金属Pd、Au、Cu以及合金PdM3、Pd2M2 和Pd3M(111)表面的吸附(M=Au, Cu), 得到了覆盖率为0.25时最稳定的吸附位、结合能以及吸附前后表面的驰豫情况. 结果表明, 氢和硫均与Pd形成最稳定的吸附, Cu次之, Au的吸附最弱, 其在三种纯金属(111)表面的最稳定吸附位均为fcc位. 由于PdAu合金具有较大的晶格常数, Pd3Au 合金吸附氢的结合能甚至较纯Pd更大, 除此之外, 氢和硫在PdM合金表面的吸附基本随M组分的增加而减弱, 而最稳定的吸附位随金属种类和组成变化而变化. 根据计算得到的吸附结合能, 发现与PdCu合金相比, PdAu合金在Au含量较低(约25%, 摩尔分数)时, 氢和硫吸附的结合能下降较慢, 而Au含量较高(跃50%)时, 结合能迅速下降, 这表明含金量为25%-50%的PdAu合金有可能在保持相近透氢性能的同时, 比PdCu合金具有更好的抗硫毒性.     

Gas sensor array based on metal-decorated carbon nanotubes

Here we demonstrate design, fabrication, and testing of electronic sensor array based on single-walled carbon nanotubes (SWNTs). Multiple sensor elements consisting of isolated networks of SWNTs were integrated into Si chips by chemical vapor deposition (CVD) and photolithography processes. For chemical selectivity, SWNTs were decorated with metal nanoparticles. The differences in catalytic activity of 18 catalytic metals for detection of H(2), CH(4), CO, and H(2)S gases were observed. Furthermore, a sensor array was fabricated by site-selective electroplating of Pd, Pt, Rh, and Au metals on isolated SWNT networks located on a single chip. The resulting electronic sensor array, which was comprised of several functional SWNT network sensors, was exposed to a randomized series of toxic/combustible gases. Electronic responses of all sensor elements were recorded and the sensor array data was analyzed using pattern-recognition analysis tools. Applications of these small-size, low-power, electronic sensor arrays are in the detection and identification of toxic/combustible gases for personal safety and air pollution monitoring.     

2-乙基蒽醌在双金属整体式催化剂上的氢化反应: 实验和DFT研究

过氧化氢(H2O2)是一种绿色化工原料和环境友好氧化剂. 目前, 超过 98% 的H2O2是通过蒽醌法生产. 蒽醌法主要包括 2-乙基蒽醌氢化生成 2-乙基氢蒽醌和 2-乙基氢蒽醌氧化生成 2-乙基蒽醌和H2O2的过程. 其中, 2-乙基蒽醌氢化是关键步骤. 在氢化过程中, 生成的 2-乙基氢蒽醌和四氢-2-乙基氢蒽醌是目标产物, 同时生成许多副产物. 目前, Pd 颗粒催化剂是广泛使用的催化剂, 但是蒽醌氢化过程中, 质量传递是主要的控制因素. 与颗粒催化剂对比, 整体式催化剂可以减弱整个反应的内外扩散, 提高反应速率. 很多研究结果显示, 整体式催化剂的传质优于颗粒催化剂, 可以提高催化效率. 近期许多研究显示, 双金属颗粒催化剂在很多氢化反应中体现出优异的催化性能. 本工作制备了双金属整体式催化剂, 考察了其在蒽醌氢化过程中的催化性能.首先, 通过浸渍法制备了4 种双金属整体式催化剂 Pd-M/SiO2/COR (M = Ni, Fe, Mn和 Cu)以及Pd/SiO2/COR和Ni/SiO2/COR两种单金属整体式催化剂. 催化活性结果显示, Ni/SiO2/COR的H2O2产量低于 Pd/SiO2/COR, 而且在 700 oC还原的 Pd-Ni/SiO2/COR 整体式催化剂在 Pd/M = 2 时取得了最高选择性 (95.3%) 和H2O2产量 (7.5 g/L). 然后, 考察了金属负载量的影响. 结果显示, 在金属负载量低于 0.4% 时, 随着金属负载量增加, 选择性和H2O2产量增加, 在金属负载量高于0.4% 时, 随着金属负载量增加, 选择性和H2O2产量降低. TEM结果表明, 添加第二种金属后, 双金属整体式催化剂颗粒尺寸变小, 分布更均匀. EDS结果显示, 双金属形成了合金. H2-TPR结果显示, 随着Pd/M比率增加, 还原温度降低, 说明Pd有助于第二种金属氧化物的还原. 这可能是由于 Pd 表面的氢溢流到第二种金属 (Ni, Fe, Mn和 Cu) 表面. 此外, 文献结果表明, 合金的形成能够抑制 PdH 的形成. 本工作表明添加第二种金属 (Ni, Fe, Mn和Cu) 后, PdH 的峰强度减弱或者峰消失, 也说明形成了合金. XPS 结果显示, 添加第二种金属后,在 336.3 ± 0.1 和 341.4 ± 0.1 eV 出现了新的 Pd 3d5/2和 Pd 3d3/2峰, 说明形成了合金. H2-O2滴定结果表明, Pd-Ni/SiO2/COR的Pd分散度和Pd比表面积都高于其他双金属催化剂, 说明第二种金属 Ni 更有利于促进 Pd 的分散, 减弱颗粒集聚, 揭示了Pd 和 Ni 之间强烈的相互作用. DFT 计算结果显示, Pd3M1(M = Ni, Fe, Mn和Cu) 双金属整体式催化剂和 2-乙基蒽醌之间的结合能低于 Pd/SiO2/COR和 2-乙基蒽醌之间的结合能, 但是 Pd3M1(M = Ni, Fe和Mn) 双金属催化剂和 2-乙基氢蒽醌之间的结合能减小得很少, 这可能是由于 2-乙基蒽醌的 C=O 和第二种金属之间具有强烈相互作用的缘故. Pd3Cu1双金属催化剂和 2-乙基氢蒽醌之间的结合能减小很多, 主要是由于 Pd3Cu1表面不利于 2-乙基氢蒽醌的吸附.因此, Pd-Ni/SiO2/COR 比 Pd/SiO2/COR, Ni/SiO2/COR 和其他的双金属整体式催化剂具有更高的选择性和H2O2产量, 主要是由于合金的形成以及 2-乙基氢蒽醌的 C=O 双键和 2-乙基氢蒽醌强烈的相互作用.     

Adsorption and Decarbonylation Reaction of Furfural on the Pd(111) and M/Pd(111)(M=Ni,Cu and Ru) Surfaces

By performing with density functional theory(DFT) method, the detailed adsorption process and the catalytic decarbonylation mechanisms of furfural over Pd(111) and M/Pd(111)(M = Ni, Cu, Ru) surfaces toward furan were clarified. The results of atomic size factor, formation energy and d-band center showed that Ru/Pd(111) surface was the most stable and active. The adsorption energies of furfural on the different surfaces followed the order Ru/Pd(111) Cu/Pd(111) Pd(111) Ni/Pd(111). After analyzing Mulliken atomic charge population and the deformation density, we can find that on Ru/Pd(111) surface, the number of charge transfer was the most and the interaction was the strongest. Therefore, its adsorption energy was the highest. Furthermore, the furfural decarbonylation pathway is more kinetically feasible on bimetallic surface, and the reaction is the most likely to occur on Ru/Pd(111).     

Pd/SWNTs负载型催化剂的制备及其催化性能

利用单壁碳纳米管(SWNTs)自身的还原性, 将PdCl2溶液中的Pd2+直接还原成金属Pd负载在SWNTs表面上, 制备了具有良好催化性能的Pd/SWNTs负载型催化剂. 通过透射电镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和热重分析(TG)对Pd/SWNTs 进行了表征, 并利用Suzuki反应对Pd/SWNTs的催化性能进行了测试. 实验结果表明, 用SWNTs与12 mmol·L-1的PdCl2的水溶液直接作用, 得到Pd/SWNTs催化材料的Pd负载量达到14.13%(w, 质量分数), 颗粒分散均匀, 粒径小(2 nm左右), 与SWNTs结合紧密; 用经过H2还原的Pd/SWNTs作催化剂, 在90 ℃下进行Suzuki反应, 30 min后反应就基本完成, 其联苯的产率达到98.10%, 催化活性较高, 可望广泛用于有机合成反应.