Pt adsorption on the PbTiO3(110) polar surface: a density functional theory study

The monolayer (ML) and submonolayer Pt on both terminations of PbTiO₃(110) polar surface have been studied by using density functional theory (DFT) with projector‐augmented wave(PAW) potential and a supercell approach. The most favored ML Pt arrangements on PbTiO and O₂ terminations are the hollow site and the short‐bridge site, respectively. By examining the geometries of different ML arrangements, we know that the dominant impetus for stability of the favored adsorption site for PbTiO termination is the Pt–Ti interaction (mainly from covalent bonding), while that for O₂ termination is the Pt–O interaction (mainly from ionic bonding). In addition, the appearance of the gap electronic states in the outermost layers of each termination indicates that a channel for charge transfer between adsorbed layer and substrate is formed. Moreover, the interface hybridization between Pt 5d and O 2p orbitals is also observed, especially for ML Pt on O₂ termination. The stability sequences for various arrangements of 1/2 ML Pt adsorption conform well with those of ML Pt adsorption, and the most stable arrangement is energetically more favorable than the corresponding ML coverage in the view of adsorption energy maximization. The behavior, i.e. the increase in adsorption energy with decrease in coverage, indicates that Pt? Pt interactions weaken those between Pt and the substrate. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural characterisation of [Pt(NH3)4]2[W(CN)8][NO3]·2H2O donor–acceptor complex

The bimetallic [Pt(NH₃)₄]₂[W(CN)₈][NO₃]·2H₂O is characterised by single-crystal X-ray diffraction [S.G.P2₁/m(11), a=8.0418(7), b=19.122(2), c=9.0812(6) Å, Z=2]. All platinum centres have the square-plane D_4h geometry with average dimensions Pt(1)–N 2.042(2) and Pt(2)–N 2.037(10) Å. The octacyanotungstate anion has the square-antiprismatic D_4d configuration with average dimensions W(1)–C 2.164(13), C–N 1.140(12), W(1)–N 3.303(5) Å. The structure exhibits two different mutual orientations of Pt versus W units resulting in Pt(2)–W(1), W(1)^* separations of 4.77(2), 4.55(2)^* and Pt(1)–W(1) of 6.331(8) Å. A centrosymmetric structure reveals groups of two distinct columns: the first is formed by intercalated NO₃⁻ between parallel [Pt(1)(NH₃)₄]²⁺ planes and the second consists of [W(CN)₈]³⁻ interlayered by, parallel to square faces of W-antiprisms, [Pt(2)(NH₃)₄]²⁺. The structure is stabilised through a three-dimensional hydrogen bond network via nitrogen atoms of cyanide ligands, hydrogen atoms of NH₃ ligands, water molecules and oxygen atoms of NO₃⁻ counteranions. The vibrational pattern and the range of ν(CN) frequencies attributable to the electronic environment of W(V) and W(IV) are consistent with the ground state Pt(II)↔W(V) charge transfer.     

First-principles study of the adsorption of formaldehyde on the clean and atomic oxygen covered Cu(1 1 1) surface

The interaction of formaldehyde with the clean and atomic oxygen-covered Cu(1 1 1) surfaces has been studied by means of cluster model density functional calculations in which Cu₂₂(14,8) is used to represent the perfect Cu(1 1 1) surface. The calculations point towards a η¹-H₂CO---O orientation with the oxygen atom almost on top of a copper surface atom. The formaldehyde adsorption energy is of 22–25 kJ/mol and the internal geometry of adsorbed formaldehyde is almost identical to that of the molecule in the gas-phase. The C---O bond is almost parallel to the surface and the conformation with the molecular plane normal to the surface is slightly preferred to the conformation with the molecular plane nearly parallel to the surface. A Cu₂₂---O model where atomic oxygen is adsorbed on a fcc hollow site was used to study the co-adsorption and reaction of formaldehyde with atomic oxygen. Oxygen co-adsorption has a dramatic effect on the formaldehyde adsorption energy which is increased by 50%. The calculated energy barrier for the formation of the dioxymethylene intermediate species through the H₂CO+O→H₂CO₂ reaction is of 36 kJ/mol.     

3D equilibrium crystal shapes of Pb: the significance of step-resolved images

Scanning tunnelling microscopy has proven to be an extremely useful technique for imaging small crystallites equilibrated at elevated temperature. As an example, we review recent work on three-dimensional Pb crystallites of 1–2 μm diameter, supported on Ru(0 0 1). Large (1 1 1) facets and, depending on temperature, small (1 1 2) facets were observed in the top section of the crystallites. The temperature dependent facet anisotropy was analyzed to yield the absolute step free energies of Pb(1 1 1) vicinal steps. The vicinal region close to the (1 1 1) facet was studied in detail to determine the shape exponent, the step–step interaction energy and the constant of the dipole interaction potential. Boundary conditions of the evaluated vicinal region have been specified for proving the universality of shapes, characterized by the exponent of 3/2, which is clear evidence for the 1/x² step interaction potential. The role of the activation barrier for facet growth or shrinkage is discussed in the context of attaining 3D equilibrium of crystallites. A comparative study of crystallites with defect-free and dislocated facets shows significant differences, providing direct evidence of the activation barrier. Reliable step–step interaction energies were obtained for dislocated crystallites. Extrapolating the temperature dependent total step interaction energy to 0 K yields for the first time values of the structure dependent dipole–dipole step interaction energies of A- and B-steps.     

一氧化碳辅助钯、铂纳米晶的形貌控制

形貌控制对调控贵金属纳米晶的催化和光学性能至关重要．近年来,在发展铂、钯纳米晶的形貌控制的方法过程中,一氧化碳（CO）不仅作为合成铂、钯纳米晶的优良还原剂,还可通过在特定晶面的选择性吸附辅助铂、钯纳米晶的形貌控制．CO辅助铂、钯纳米晶形貌控制的方法正逐步展现出独特的优越性,甚至帮助我们制备了一些目前其他方法所无法制备的纳米晶．该综述文章首先从表面科学的角度分析讨论CO分子在铂、钯单晶面上的不同吸附行为,然后总结分析了CO调控铂、钯纳米晶形貌的几个典型例子（超薄钯纳米片、介晶钯纳米花、钯四角叉／四面体以及铂纳米立方体、铂钴削角八面体）,讨论了CO在控制铂、钯纳米晶的形貌控制作用及其化学本质,最后提出CO在辅助贵金属纳米晶的形貌控制中的挑战和展望．     

一氧化碳分子在Pt/t-ZrO2(101)表面的吸附性质

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CO分子在完整与Pt负载的四方ZrO2(101)表面的吸附行为.结果表明:表面第二层第二氧位和表面第二桥位分别为CO分子和Pt原子在完整ZrO2(101)表面的稳定吸附位,且覆盖度为0.25ML(monolayer)时均为稳定吸附构型,吸附能分别为56.2和352.7kJ·mol-1.CO分子在负载表面的稳定吸附模式为C-end吸附,吸附能为323.8kJ·mol-1.考察了CO分子在负载表面吸附前后的振动频率、态密度和轨道电荷布居分析,并与CO分子和Pt原子在ZrO2表面的结果进行比较.结果表明,C端吸附CO分子键长为0.1161nm,与自由的和吸附在ZrO2表面后的CO相应值(0.1141和0.1136nm)相比伸长.吸附后C―O键伸缩振动频率为2018cm-1,与自由CO分子相比发生红移;吸附后CO带部分正电荷,电子转移以Pt5dCO2π的π反馈机理占主导地位.     

The adsorption, CMC determination and corrosion inhibition of some N-alkyl quaternary ammonium salts on carbon steel surface in 2 M H2SO4

Electrochemical measurements were performed to investigate the effectiveness of cationic surfactants of the N-alkyl quaternary ammonium salt type, i.e. myristyltrimethylammonium chloride (MTACl), cetyldimethylbenzylammonium chloride (CDBACl), and trioctylmethylammonium chloride (TOMACl), as corrosion inhibitors for type X4Cr13 ferritic stainless steel in 2 M H₂SO₄ solution. Potentiodynamic polarization measurements showed that these surfactants hinder both anodic and cathodic processes, i.e. act as mixed-type inhibitors. It was found that the adsorption of the N-alkyl ammonium ion in 2 M H₂SO₄ solution follows the Langmuir adsorption isotherm. Plots of log [θ/(1 − θ)] versus log c_inh yielded straight lines with a slope, which changed drastically at the critical micelle concentration (CMC) of the surfactants studied. Accordingly, the CMC could be accurately determined from these measurements. The calculated values of the free energy of adsorption ΔG_ads are, in cases when the charge on the metal surface is negative with respect to the PZC, relatively high what is characteristically for the chemisorption. On the other hand, for positive metal surfaces it is assumed that SO₄²⁻ anions are adsorbed first, so the cationic species would be limited by the surface concentration of anions. Accordingly ΔG_ads values were lower in this case and the adsorption is due to merely electrostatic attraction, which is characteristically of physisorption.     

Effects and structures of the O/Cu surfactant layer in O-mediated film growth of Cu on Ru(0 0 0 1)

The O-mediated Cu-film growth on O-precovered Ru(0 0 0 1) is investigated by means of scanning tunneling microscopy for growth temperatures between 300 and 600 K. Cu-films on clean Ru(0 0 0 1) grow in a multilayer mode. For O precoverages (Θ) between 0.2 ML (monolayer) and the saturation coverage (Θ=0.5 ML), a layer-by-layer growth is observed at growth temperatures between 350 and 450 K. On Cu-islands, an O/Cu surfactant layer is formed, which floats on-top of the growing film and induces the layerwise Cu-film growth. The surface coverage of the O/Cu surfactant layer linearly rises with the O precoverage up to Θ≈0.4 ML, where it completely covers the surface. Two different types of the surfactant layer are identified, inducing different surfactant mechanisms. For Θ=0.1–0.4 ML, the O/Cu surfactant structure (A-type) displays some local order and induces inhomogeneous nucleation at the misfit-induced relaxation structure of the Cu-film. The layer-wise growth is explained by the concept of two mobilities, implying a large attempt frequency for adatom jumps over the interlayer diffusion barrier at the steps. For Θ = 0.4–0.5 ML, a disordered O/Cu surfactant layer is established (B-type), inducing homogeneous nucleation. The layer-wise Cu-film growth is attributed to a reduction of the effective interlayer diffusion barrier. Cu-film growth at 400 K on the ordered (3×2√3)O/Cu structure formed at temperatures around 520 K yields the conclusion that the O/Cu surfactant structures are composed of randomly arranged O–Cu–O strings and disrupted “Cu₂O(1 1 1)” fragments.     

Temperature dependence of adlayers on Pt(1 1 1) and Au(1 1 1) in a sulfuric acid solution studied by in situ IRAS

Temperature dependence studies of adsorption of sulfuric acid species on Pt(1 1 1) and Au(1 1 1) electrodes were carried out using in situ infrared reflection absorption spectroscopy. A temperature-dependent shift of the interconversion potential between HSO₄⁻/H₃O⁺ and H₂SO₄ on a Pt(111) electrode was observed. A temperature-dependent frequency shift of the absorption bands of HSO₄⁻ was also observed on both Pt(1 1 1) and Au(1 1 1) electrodes in the potential region where a √3×√7 structure evolved. Modelling experiments in ultrahigh vacuum revealed that ordering of the overlayer water molecules played an important role in the frequency of the absorption bands of HSO₄⁻.     

Chemical composition and reactivity of water on hexagonal Pt-group metal surfaces

The dissociation behaviour and valence-electronic structure of water adsorbed on clean and oxygen-covered Ru{0001}, Rh{111}, Pd{111}, Ir{111} and Pt{111} surfaces has been studied by high-resolution X-ray photoelectron spectroscopy with the aim of identifying similarities and trends within the Pt-group metals. On average, we find higher reactivity for the 4d metals (Ru, Rh, Pd) as compared to 5d (Ir, Pt), which is correlated with characteristic shifts in the 1b(1) and 3a(1) molecular orbitals of water. Small amounts of oxygen (< 0.2 ML) induce dissociation of water on all five surfaces, for higher coverages (> 0.25 ML) only intact water is observed. Under UHV conditions these higher coverages can only be reached on the 4d metals, the 5d metals are, therefore, not passivated.     

Thermodynamics and kinetics of oxygen-induced segregation of 3d metals in Pt-3d-Pt(111) and Pt-3d-Pt(100) bimetallic structures

The stability of subsurface 3d transition metals (3d represents Ni, Co, Fe, Mn, Cr, V, and Ti) in Pt(111) and Pt(100) was examined in vacuum and with 0.5 ML atomic oxygen by a combined experimental and density functional theory (DFT) approach. DFT was used to predict the trends in the binding energy of oxygen and in the stability of 3d metals to remain in the subsurface layer. DFT calculations predicted that for both (111) and (100) crystal planes the subsurface Pt-3d-Pt configurations were thermodynamically preferred in vacuum and that the surface 3d-Pt-Pt configurations were preferred with the adsorption of 0.5 ML atomic oxygen. Experimentally, the DFT predictions were verified by using Auger electron spectroscopy to monitor the segregation of Ni and Co in Pt-3d-Pt structures on polycrystalline Pt foil, composed of mainly (111) and (100) facets. The activation barrier for the oxygen-induced segregation of Ni was found to be 17+/-1 kcal/mol attributed to the Pt(111) areas and 27+/-1 kcal/mol attributed to the Pt(100) areas of the Pt foil. For Pt-Co-Pt, the activation barrier was found to be 10+/-1 kcal/mol and was attributed to the Pt(111) areas of the Pt foil. The Bronsted-Evans-Polanyi relationship was utilized to predict the activation barriers for segregation of the other Pt-3d-Pt(111) and Pt-3d-Pt(100) systems. These results are further discussed in connection to the activity and stability for cathode bimetallic electrocatalysts for proton exchange membrane fuel cells.     

Calorimetric determination of the acidic character of amorphous and crystalline aluminosilicates

Aluminosilicates can present different structures such as crystalline true zeolite molecular sieves or amorphous silica–aluminas. With a large surface area available, both can be involved as catalysts, adsorbents or catalyst supports, and the determination of their surface acidic properties is an important parameter in the study of such materials.

The number, strength and strength distribution of the acidic sites were determined using microcalorimetry linked to a volumetric line. Ammonia was used as a basic probe molecule. The adsorption temperatures ranged from 353 K up to 473 K. The samples consisted of two amorphous silica–aluminas (Si/Al ≈ 6.5) and three microporous zeolites H-β, H-ZSM-5 and H-MCM-22 with similar Si/Al ratios (Si/Al ≈ 13).

The differential heats of ammonia adsorption versus coverage and the corresponding isotherms are given. The H-ZSM-5, H-MCM-22, H-β samples display a plateau of constant adsorption heats near 150 kJ mol⁻¹, while the silica–alumina samples present continuously decreasing heats from 150 kJ mol⁻¹ at zero coverage to 40 kJ mol⁻¹ at high coverage, due to their surface heterogeneity. For amorphous silica–aluminas, the number of acid sites is dependent of the aluminum distribution at the surface.

The differences observed in the adsorption behavior of ammonia over the three zeolites arise from differences in their morphology, i.e. the total free volumes, pore geometries and electric field gradients at the adsorption sites. The adsorption isosteres have also been calculated from the adsorption isotherms, and the isosteric heats of adsorption have been compared with the heats measured by calorimetry.     

Influence of electronic and steric effects on stability constants and electrochemical reversibility of divalent ion complexes with glycine and sarcosine. A glass electrode potentiometric, sampled direct current polarographic, virtual potentiometric, and molecular modelling study

Cd^II complexes with glycine (gly) and sarcosine (sar) were studied by glass electrode potentiometry, direct current polarography, virtual potentiometry, and molecular modelling. The electrochemically reversible Cd^II–glycine–OH labile system was best described by a model consisting of M(HL), ML, ML₂, ML₃, ML(OH) and ML₂(OH) (M = Cd^II, L = gly) with the overall stability constants, as log β, determined to be 10.30 ± 0.05, 4.21 ± 0.03, 7.30 ± 0.05, 9.84 ± 0.04, 8.9 ± 0.1, and 10.75 ± 0.10, respectively. In case of the electrochemically quasi-reversible Cd^II–sarcosine–OH labile system, only ML, ML₂ and ML₃ (M = Cd^II, L = sar) were found and their stability constants, as log β, were determined to be 3.80 ± 0.03, 6.91 ± 0.07, and 8.9 ± 0.4, respectively. Stability constants for the ML complexes, the prime focus of this work, were thus established with an uncertainty smaller than 0.05 log units. The observed departure from electrochemical reversibility for the Cd–sarcosine–OH system was attributed mainly to the decrease in the transfer coefficient . The MM2 force field, supplemented by additional parameters, reproduced the reported crystal structures of diaqua-bis(glycinato-O,N)nickel(II) and fac-tri(glycinato)-nickelate(II) very well. These parameters were used to predict structures of all possible isomers of (i) [Ni(H₂O)₄(gly)]⁺ and [Ni(H₂O)₄(sar)]⁺; and (ii) [Ni(H₂O)₃(IDA)] and [Ni(H₂O)₃(MIDA)] (IDA = iminodiacetic acid, MIDA = N-methyl iminodiacetic acid) by molecular mechanics/simulated annealing methods. The change in strain energy, ΔU_str, that accompanies the substitution of one ligand by another (ML + L′ → ML′ + L), was computed and a strain energy ΔU_str = +0.28 kcal mol⁻¹ for the reaction [Ni(H₂O)₄(gly)]⁺ + sar → [Ni(H₂O)₄(sar)]⁺ + gly was found. This predicts the monoglycine complex to be marginally more stable. By contrast, for the reaction [Ni(H₂O)₃IDA] + MIDA → [Ni(H₂O)₃MIDA] + IDA, ΔU_str = −0.64 kcal mol⁻¹, and the monoMIDA complex is predicted to be more stable. This correlates well with (i) stability constants for Cd–gly and Cd–sar reported here; and (ii) known stability constants of ML complex for glycine, sarcosine, IDA, and MIDA.     

Acetaldehyde on Pt(111) and Pt/Sn(111): a DFT study of the adsorption structures and of the vibrational spectra

The relative stability of the eta1mu1 (atop) and eta2mu2 (di-sigma) geometries of acetaldehyde are compared on Pt(111) and on two PtSn alloys ((2 x 2) and (square root(3) x square root(3))R30 degrees) by means of density functional theory (DFT) calculations. At low coverage on Pt (1/9 ML), the two forms are equivalent in energy, with eta1mu1 being slightly more stable. At high coverage (1/4 and 1/3 ML), eta2mu2 is less competitive and acetaldehyde is adsorbed through the aldehydic hydrogen. The evolution of the adsorption energy with the coverage and the apparition of the structure adsorbed through the aldehydic hydrogen are explained by the existence of attractive dipole-dipole interactions. On PtSn, only the eta1mu1 geometry is stable with an adsorption energy equal to that on Pt, in agreement with temperature-programmed desorption (TPD) experiments. The calculated vibrational spectra allow us to conclude that the experimental spectrum corresponds to a mixture of eta1mu1 (majority) and eta2mu2 (minority) structures on Pt and to only eta1mu1 on PtSn. The various interactions and the relative stability of the species on Pt and PtSn are explained by the density of states (DOS) curves.     

Electronic properties of Pt in bimetallic systems: photoemission and molecular-orbital studies for Pt---Al surface alloys

The adsorption of Pt on polycrystalline Al leads to the formation of surface alloys. The electronic properties of these systems have been examined using XPS and ab initio SCF calculations. The Pt---Al surface alloys display a Pt(5d) band that appears at much higher binding energy (≈ 1.8 eV) than in metallic Pt. This is accompanied by positive shifts in the Pt 4f (≈ 1.2 eV) and Al 2s (≈ 0.2 eV) levels. The Pt---Al bond is complex, involving an Al(3s, 3p) → Pt(6s, 6p) charge transfer and a Pt(5d) → Pt(6s, 6p) rehybridization that localize electrons in the region between the two metal centers.     

Pt原子在γ-Al2O3(001)表面的吸附及迁移

采用密度泛函理论(DFT)中广义梯度近似(GGA)方法, 对Pt原子与γ-Al₂O₃(001)面的相互作用及迁移性能进行了研究. 分析了各种可能吸附位及吸附构型的松弛和变形现象, 吸附能和迁移能垒的计算结果表明: Pt团簇能够稳定吸附在该表面. Pt原子在表面O位的吸附能明显较高, 这主要是由Pt向基底O原子转移了电子所致. 电荷布居分析表明, Pt原子显电正性, Pt和Al原子之间存在排斥作用, 导致与Al原子产生较弱相互作用. 计算的平均吸附能大小依赖于Pt团簇的大小和形状, 总体趋势是随着Pt原子数增多, 吸附能降低. Pt原子在γ-Al₂O₃(001)表面迁移过程所需克服的迁移能垒最高值为0.51 eV. 随着吸附的Pt原子数增多,更倾向于形成Pt团簇. 因此, Pt原子在γ-Al₂O₃(001)表面的吸附演变不可能形成光滑、均匀平铺的吸附构型, 而在一定条件下容易出现团聚.     

Assembly of molecular squares and helical chain polymers of Mo(W)/Cu/S clusters using thiolato ligands as linkers

Reactions between thiomolybdate or thiotungstate [Et₄N]₂[MS₄] (M = Mo, W) and CuSBu^t led to the formation of two novel Mo(W)/Cu/S clusters [Et₄N]₄[{MS₄Cu₂(μ-SBu^t)}₄] (1, M = Mo; 2, M = W). Single-crystal X-ray diffraction studies reveal that 2 is the first example of a molecular square containing CuS₂WS₂Cu building blocks. The reactions of [Et₄N]₂[MS₄] with CuCl followed by the addition of K₂SSS (SSS = 1,3,4-thiadiazole-2,5-dithiolate) yielded novel polymers {[Et₄N]₂[MS₄Cu₂(SSS)]}_n (3, M = Mo; 4, M = W). Crystal structure determination shows that the CuS₂WS₂Cu building blocks in the anion of 4 are bridged by SSS²⁻ ligands to produce a helical chain running down the crystallographic b axis.     

Theoretical and experimental study of the inelastic neutron scattering spectra of β-5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one

The inelastic neutron scattering (INS) spectra of β-5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (β-NTO) are presented to 1400 cm⁻¹. The β-NTO vibrational frequencies observed differ considerably from the -NTO vibrational frequencies and normal mode frequency calculations for the isolated molecule. The INS spectrum contains detail unobserved in the previous IR studies, including combinations and overtones of the phonon and internal modes of β-NTO. The INS spectra are compared with periodic DFT calculations to show that the periodic DFT results correctly predict the solid-state molecular vibrational frequencies.     

Physico-chemical and thermodynamic aspects of fibroblastic attachment on RGDS-modified chitosan membranes

In the present study, the cell attachment/spreading behaviour of L929 mouse fibroblasts on chitosan membranes was evaluated by using physico-chemical properties. For this purpose chitosan membranes were prepared and then photochemically modified with the cell adhesive peptide RGDS (Arg-Gly-Asp-Ser). The physico-chemical properties of unmodified (CHI) and RGDS-modified chitosan (CHI-RGDS) membranes were evaluated by calculating surface free energy (γ_sv) and interfacial free energy (γ_sw) values using captive bubble contact angle measurements and harmonic mean equation. The cell attachment experiments were performed both in 10% FBS containing and serum-free media with CHI and CHI-RGDS membranes. Eventually, it was not possible to predict a direct relationship between the change in physico-chemical properties and L929 cell attachment behaviour. The experimental results obtained from cell attachment agree with the theoretical prediction for the free energy of adhesion except for the cell attachment on CHI membrane in serum-free medium. Although a negative interfacial free energy of adhesion was calculated for CHI membrane in serum-free medium (ΔF_adh = −2.19 ergs/cm²), the cell attachment was poor (70%) compared to CHI-RGDS (90%) and none of the cells were spread on CHI surface to gain a fibroblastic morphology. Negative energy of adhesion was calculated for CHI and CHI-RGDS in 10% FBS medium, in which 100% of cells were attached on the membranes correlating with the thermodynamic approach. It can be suggested that, adsorption of serum proteins strongly affected the cell attachment meanwhile the presence of biosignal RGDS molecules triggered the cell spreading in serum medium.     

氢原子在Pt及Pt系双金属催化表面吸附的密度泛函理论研究

采用密度泛函理论(dFT)考察了Pt(100)、(110)、(111)三种表面氢原子的吸附行为, 计算了覆盖度为0.25 ML时氢原子在Pt 三种表面和M-Pt(111)双金属(M=Al, Fe, Co, Ni, Cu, Pd)上的最稳定吸附位、表面能以及吸附前后金属表面原子层间弛豫情况. 分析了氢原子在不同双金属表面吸附前后的局域态密度变化以及双金属表面d 带中心偏离费米能级的程度并与氢吸附能进行了关联. 计算结果表明, 在Pt(100), Pt(110)和Pt(111)表面, 氢原子的稳定吸附位分别为桥位、短桥位和fcc 穴位. 三种表面中以Pt(111)的表面能最低, 结构最稳定. 氢原子在不同M-Pt(111)双金属表面上的最稳定吸附位均为fcc 穴位, 其中在Ni-Pt 双金属表面的吸附能最低, Co-Pt 次之. 表明氢原子在Ni-Pt 和Co-Pt 双金属表面的吸附最稳定. 通过对氢原子在M-Pt(111)双金属表面吸附前后的局域态密度变化的分析, 验证了氢原子吸附能计算结果的准确性. 掺杂金属Ni、Co、Fe 的3d-Pt(111)双金属表面在吸附氢原子后发生弛豫, 第一层和第二层金属原子均不同程度地向外膨胀. 此外, 3d金属的掺入使得其对应的M-Pt(111)双金属表面d带中心与Pt 相比更靠近费米能级, 吸附氢原子能力增强, 表明3d-Pt系双金属表面有可能比Pt具有更好的脱氢活性.