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The applicability of a heteroaromatic photoredox catalyst in an additive-free photo-mediated hydroamination of stilbenes is described. Initiated by the excitation of a highly potent organic pyrimid...

Structures, energies, and stability of aliphatic PNP ligated CoIII/CoI amine and amido complexes in different spin (singlet, triplet, and open-shell singlet) states and coordination spheres have be...

The mechanisms of iridium-catalyzed nonoxidative conversion of light hydrocarbons have been computed on flat Ir(111) and stepped Ir(211) surfaces under given conditions. On Ir(111), CH4 dissociatio...

Periodic density functional theory calculations were employed to study the mechanisms of H2O dissociative adsorption on the Ni(211) surface at different coverages. Due to stronger H-bonding, H2O cl...

Here, we describe a selective palladium catalyst system for chemodivergent functionalization of alkynes with syngas. In the presence of the advanced ligand L2 bearing 2-pyridyl substituent as a bui...

To investigate the hydrocracking mechanisms of polycyclic aromatic hydrocarbons, we used HZSM-5 with one Al substitution (T1, T3, T5, T7, T11 and T12) as solid acid catalyst and 9,10-dihydroanthrac...

Reduction of carbonyl moieties to the corresponding alcohol using simply hydrazine hydrate has been considerably unfeasible until now due to the well-known condensation reaction. However, herein, we report that using an excess of 20-fold equivalents, the reduction proceeds in excellent yields.

A few years ago, we introduced alternative-type bulk ZrO2-based catalysts for nonoxidative propane dehydrogenation (PDH). Currently, they belong to the state of the art catalysts owing to their env...

In this work, steady-state tests of propane dehydrogenation, density functional theory calculations, operando UV–vis spectroscopy, ex situ and in situ electron paramagnetic resonance spectroscopy, ...

For the hydroformylation of alkenes, developing ligand-free heterogeneous catalysts is a research focus because of both fundamental research interests and potential commercial applications. However...

Experimentally, surface carbon hydrogenation on metallic iron forms CH4, ethylene/ethane, and propene/propane, while previous density functional theory studies showed that these reactions are highly endothermic. This disagreement can be attributed to the shortcoming of low coverage of surface carbon atoms and the underestimated role of surface hydrogen. On a p(4 × 4) Fe(110) surface with 0.25 ML carbon coverage (4 C atoms) and other free sites filled with H atoms, we studied surface C hydrogenation with spectators and found that the formation of CH4, ethylene/ethane, and propene/propane becomes exothermic. Coupling of CH + CH and CH3C + CH to acetylene and propylene is favored thermodynamically. Next, CHCH and CH3CCH can be hydrogenated into CH2CH and CH3CHCH, and the subsequent hydrogenation of CH2CH and CH3CHCH determines the formation and selectivity of alkenes and alkanes. The most important surface species is carbide HC for chain initiation or CH3C (RC for higher homolog) for chain propagation. This ...

The catalytic dehydrocoupling of hydrazine borane (N2H4·BH3, HB) using two molecularly defined PNP Fe(II) hydride complexes [(PNHP)Fe(HBH3)(H)(CO)] (PNHP = HN[CH2CH2P(i-Pr)2], 1-BH3) and [(PNP)Fe(H...

Dissociation of CO often occurs on Ru surfaces with dense chemisorbed CO (CO*) adlayers, ubiquitous in the practice of catalysis, where the strong bond in CO tends to weaken via bimolecular reactions with H2 before cleavage. Nevertheless, H2 adsorption on CO*-crowded Ru surfaces is a rare event because of the CO*-induced barrier and the competitive adsorption between CO and H2. Here, we thereby performed a comprehensive ab initio study of the coadsorption of CO and H2 as well as the following initiation reaction on Ru(0001). At 100–550 K (3 MPa, H2/CO = 2), Ru(0001) is always saturated, covered by CO with a “hexagonal” pattern, where H2 adsorption is neither kinetically nor thermodynamically favored. On the basis of a systematic analysis of the electronic structure, we find that two adjacent coadsorbed CO* can serve as a promoter for the scission of the H–H bond in H2(g), leading to the simultaneous formation of two COH* molecules in one step (Ea = 1.64 eV). This so-called CO self-promoting hydrogenation ...

CO adsorption on the perfect Ir(111) as well as the unreconstructed Ir(100) and Ir(110) surfaces at different coverages has been computed at the level of periodic density functional theory. General...

The morphology change of metallic nanoparticles induced by the interaction of gas molecules with nanoparticles is a very important surface chemistry process in heterogeneous catalysis. Here, we performed a thorough study to provide understanding of the influence of CO adsorption on theoretically established Ru nanoparticle models through an approach combining density functional theory, Wulff construction, and ab initio atomistic thermodynamics. The morphology of constructed Ru nanoparticles undergoes significant evolution upon changing CO coverage, exposed temperature, and pressure. The contribution from flat facets becomes more significant in equilibrium morphology of nanoparticles as the surface CO coverage increases. Such morphological evolution has a consequential impact on the inherited catalytic performance of Ru NPs, as they were applied into three probe catalytic reactions, CO direct dissociation, HCO formation, and CH3 hydrogenation. This study enriches the current knowledge of the ruthenium nano...

To understand the mechanisms of Fe-based Fischer–Tropsch synthesis in a retrosynthetic way, successive dissociation of CH4, C2H6, and CH3CHO on the Fe(110) p(5 × 5) surface has been systematically computed using density functional theory. The successive dissociation of CH4 [CH4 → H + CH3 → 2H + CH2 → 3H + CH → 4H + C] and C2H6 [C2H6 → H + CH3CH2 → 2H + C2H4 → 3H + CHCH2 → 4H + CHCH → 4H + CH + CH] has close apparent barrier (0.69 and 0.65 eV, respectively) and is highly exothermic (−2.47 and −3.17 eV). The CH3CHO successive dissociation is barrierless and favors the minimum energy path of CH3CHO → H + CH3CO → 2H + CH2CO → 3H + CHCO → 4H + CH + CO. All of these successive dissociations result in the formation of surface species H, C, and CO, which are related with the initial steps of the adsorption and activation of H2 and CO. It is particularly noted that the computed results that ethylene dissociates easily into acetylene and acetylene dissociates reversibly into CH + CH agree with that experimentally o...

To understand the initial steps of Fe-based Fischer–Tropsch synthesis, systematic periodic density functional theory computations have been performed on the single-atom stepped Fe(710) surface, composed by p(3 × 3) Fe(100)-like terrace and p(3 × 1) Fe(110)-like step. It is found that CO direct dissociation into surface C and O is more favored kinetically and thermodynamically than the H-assisted activation via HCO and COH formation. Accordingly, surface O removal by hydrogen via H2O formation is the only way. On the basis of surface CHx hydrogenation (x = 0, 1, 2, 3), surface CHx + CHx coupling and CO + CHx insertion resulting in CHxCO formation followed by C–O dissociation, surface C hydrogenation toward CH3 formation is more favored kinetically than the formation of CHx-CHx and CHxCO, as well as thermodynamically. Starting from CH3, the formation of CH4 and CH3CO has similar barriers and endothermic reaction energies, while CH3CO dissociation into CH3C + O has low barrier and is highly exothermic. There...

A series of P-chirogenic Xantphos ligands and related diaryl ether diphosphines have been synthesized by a modification of the well-established Juge method. The approach consists of the in situ deboranation of the chiral ephedrine-based phosphinite before the P–C coupling takes place. The stereochemical integrity of the stereocenters of the diphosphines during synthesis, long-time storage, and catalytic application was evaluated. In the rhodium-catalyzed asymmetric hydrogenation of isophorone as a model substrate for industrially relevant prostereogenic enones with some of the diphosphines, almost complete conversion, high chemoselectivity, and 96% ee were achieved.

Ruthenium PNP complex 1a (RuH(CO)Cl(HN(C2H4Pi-Pr2)2)) represents a state-of-the-art catalyst for low-temperature (2 and CO2. Herein, we describe an investigation that combines experiment, spectroscopy, and theory to provide a mechanistic rationale for this process. During catalysis, the presence of two anionic resting states was revealed, Ru-dihydride (3-) and Ru-monohydride (4-) that are deprotonated at nitrogen in the pincer ligand backbone. DFT calculations showed that O- and CH- coordination modes of methoxide to ruthenium compete, and form complexes 4- and 3-, respectively. Not only does the reaction rate increase with increasing KOH, but the ratio of 3-/4- increases, demonstrating that the "inner-sphere" C - H cleavage, via C - H coordination of methoxide to Ru, is promoted by base. Protonation of 3- liberates H2 gas and formaldehyde, the latter of which is rapidly consumed by KOH to give the corresponding gem-diolate and provides the overall driving force for the reaction. Full MeOH reforming is achieved through the corresponding steps that start from the gem-diolate and formate. Theoretical studies into the mechanism of the catalyst Me-1a (N-methylated 1a) revealed that C - H coordination to Ru sets-up C - H cleavage and hydride delivery; a process that is also promoted by base, as observed experimentally. However, in this case, Ru-dihydride Me-3 is much more stable to protonation and can even be observed under neutral conditions. The greater stability of Me-3 rationalizes the lower rates of Me-1a compared to 1a, and also explains why the reaction rate then drops with increasing KOH concentration.

The stability of ligands and catalysts is an almost neglected issue in homogeneous catalysis, but it is crucial for successful application of this methodology in technical scale. We have studied the effect of water on phosphites, which are the most applied cocatalysts in the n-regioselective homogeneous Rh-catalyzed hydroformylation of olefins. The stability of the bidentate nonsymmetrical diphosphite L1, as well as its two monophosphite constituents L2 and L3, toward hydrolysis was investigated by means of in situ NMR spectroscopy under similar conditions as applied in industry. Hydrolysis pathways, intermediates, and kinetics were clarified. DFT calculations were used to support the experimentally found data. The acylphosphite unit L2, which reacts with water in an unselective manner, was proven to be much less stable than the phenolphosphite L3. The stability of the bidentate ligand L1 can be therefore mainly attributed to its phenolphosphite moiety. With an excess of water, the hydrolysis of L1 and L2...

The selective formation of 2-methylfuran (F-CH3) and furan from furfural (F-CHO) hydrogenation and hydrodeoxygenation on clean and 4H precovered Mo2C(101) surfaces has been systematically computed on the basis of periodic density functional theory including dispersion correction (PBE-D3). The clean Mo2C(101) surface has two distinct surface sites: unsaturated C and Mo sites for the adsorption of H and furfural, respectively. The selectivity comes from the different preference of furfural hydrogenation and dissociation (F-CHO + H = F-CH2O vs F-CHO = F-CO + H) under the variation of H2 partial pressure. On the basis of the computed minimum energy path on the clean surface, microkinetics shows that high H2 partial pressure can promote 2-methylfuran formation and suppress furan formation. To verify this proposed selectivity trend of 2-methylfuran at high H2 partial pressure, the 4H precovered Mo2C(101) surface (0.25 monolayer hydrogen coverage), which provides neighboring hydrogens for promoting furfural hydr...

Three density functional approximations (DFAs), PBE, PBE+U, and Heyd–Scuseria–Ernzerhof screened hybrid functional (HSE), were employed to investigate the geometric, electronic, magnetic, and thermodynamic properties of four iron oxides, namely, α-FeOOH, α-Fe2O3, Fe3O4, and FeO. Comparing our calculated results with available experimental data, we found that HSE (a = 0.15) (containing 15% “screened” Hartree–Fock exchange) can provide reliable values of lattice constants, Fe magnetic moments, band gaps, and formation energies of all four iron oxides, while standard HSE (a = 0.25) seriously overestimates the band gaps and formation energies. For PBE+U, a suitable U value can give quite good results for the electronic properties of each iron oxide, but it is challenging to accurately get other properties of the four iron oxides using the same U value. Subsequently, we calculated the Gibbs free energies of transformation reactions among iron oxides using the HSE (a = 0.15) functional and plotted the equilibri...

Surface O removal by H and CO on Co(0001) has been studied using periodic density functional method (revised Perdew–Burke–Ernzerhof ; RPBE) and ab initio atomistic thermodynamics. On the basis of the quantitative agreement in the H2O formation barrier between experiment (1.34 ± 0.07 eV) and theory (1.32 eV), H2O formation undergoes a consecutive hydrogenation process [O + 2H → OH + H → H2O], while the barrier of H2O formation from OH disproportionation [2OH → H2O + O] is much lower (0.72 eV). The computed desorption temperatures of H2 and H2O under ultrahigh vacuum conditions agree perfectly with the experiment. Surface O removal by CO has a high barrier (1.41 eV) and is strongly endothermic (0.94 eV). Precovered O and OH species do not significantly affect the barriers of H2O and CO2 formation. All of these results indicate that the present RPBE method and the larger surface model are more suitable for studying cobalt systems.

On the basis of density functional theory including dispersion correction [ωB97XD/6-311+G(2df,2p)//B3LYP/6-311G(d,p)], the thermodynamics and kinetics of the reactions of CH3OH and CH3OCH3 over H-ZSM-5 have been systematically computed. For the reaction of the methylated surface (CH3OZ) with CH3OH, CH3OCH3 formation is kinetically controlled and the competitive formation of CH2O + CH4 is thermodynamically controlled, in agreement with the observed desorption temperatures of CH3OH, CH3OCH3, and CH2O under experimental conditions. For the reaction between ZOCH3 and CH3OCH3, the formation of the framework stabilized (CH3)3O+ is kinetically controlled, consistent with the NMR observation at low temperature, and the competitive formation of surface CH3OCH2OZ + CH4 is thermodynamically controlled. On the basis of the thermodynamically more favored CH2O and CH3OCH2OZ, there are two parallel routes for the first C–C bond formation, from the coupling of CH3OCH2OZ with CH3OH and CH3OCH3 as well as from the coupling...

Spin-polarized density functional theory calculations were performed to investigate N2 dissociative adsorption on iron (100), (110), (111), (210), (211), (310), and (321) surfaces. An ordered c(2 × 2) structure was found on Fe(100) at 0.5 monolayer coverage, which is in excellent agreement with the experiment; and a c(4 × 2) ordered structure is also found at 0.75 monolayer saturation coverage. Strong surface reconstruction is found on Fe(110) upon nitrogen adsorption, where the densely packed (110) is reconstructed into (100)-alike. Under the consideration of temperature and N2 partial pressure, the estimated N2 desorption temperature on Fe(100) at 925 K agrees with the experimentally detected 920–950 K. In addition, N2 pretreatment results in Fe(100) to be mostly exposed, while that of H2 pretreatment favors Fe(110). Further direct comparison of N2 and H2 adsorptions has been made to show their differences and similarities.

The reactions of CO and H2O on the clean Fe(110) surface as well as surfaces with 0.25 monolayer O, OH, and H precoverage have been computed on the basis of density functional theory (GGA-PBE). Under the considerations of the reductive nature of CO as reactant and H2 as product as well as the oxidative nature of CO2 and H2O, we have studied the potential activity of metallic iron in the water-gas shift reaction. On the clean surface, CO oxidation following the redox mechanism has a similar barrier as CO dissociation; however, CO dissociation is much more favorable thermodynamically. Furthermore, surfaces with 0.25 monolayer O, OH, and H precoverage promote CO hydrogenation, while they suppress CO oxidation and dissociation. On the surfaces with different CO and H2O ratios, CO hydrogenation is promoted. On all of these surfaces, COOH formation is not favorable. Considering the reverse reaction, CO2 dissociation is much favorable kinetically and thermodynamically on all of these surfaces, and CO2 hydrogenat...

The full potential energy surface of the catalytic conversion of furfural to 2-methylfuran on the Cu(111) surface has been systematically computed on the basis of density functional theory, including dispersion and zero-point energy corrections. For furfuryl alcohol formation, the more favorable step is the first H addition to the carbon atom of the C═O group, forming an alkoxyl intermediate (F-CHO +H → F-CH2O); the second H atom addition, leading to furfuryl alcohol formation (F-CH2O + H → F-CH2OH), is the rate-determining step. For 2-methylfuran formation from furfuryl alcohol dissociation into surface alkyl (F-CH2) and OH groups, H2O formation is the rate-determining step (OH + H → H2O). Our results explain perfectly the experimentally observed selective formation of furfuryl alcohol and the equilibrium of furfural/furfuryl alcohol conversion under hydrogen-rich conditions as well as the effect of H2O suppressing furfural conversion. In addition, it is found that dispersion correction (PBE-D3) overesti...

Water dissociative adsorption on the clean and O-precovered Fe(111) surfaces at different coverage have been studied using the density functional theory method (GGA-PBE) and ab initio atomistic thermodynamics. On the clean p(3 × 3) Fe(111) surface, surface H, O, OH, and H2O species can migrate easily. Considering adsorption and H-bonding, the adsorbed H2O molecules can be dispersed or aggregated in close energies at low coverage, while in different aggregations at high coverage, indicating that the adsorbed H2O molecules might not have defined structures, as observed experimentally. On the O-precovered surface (nO = 1–8), the first dissociation step, nO + H2O = (n – 1)O + 2OH, has a very low barrier and is reversible; and the barriers of the sequential OH dissociation steps, (n – 1)O + 2OH = nO + H + OH and nO + H + OH = (n + 1)O + 2H, are close (0.9–1.2 eV). All of these barriers are coverage independent. For OH and H adsorption at 1/3 ML coverage, surface OH forms a trimer (OH)3 unit, and surface O form...

Spin-polarized density functional theory computations have been carried out to investigate the surface morphology of Cun adsorption on the Fe5C2(100), Fe5C2(111), Fe5C2(510), Fe5C2(001), and Fe5C2(010) surface terminations in different surface Fe and C ratios. On the Fe5C2(100), and Fe5C2(510) surfaces, aggregation is thermodynamically more favored than dispersion, while dispersion is more favored than aggregation on the Fe5C2(111) surface for n = 2–4, on the Fe5C2(010) surface for n = 2 and on the Fe5C2(001) surface for n = 2–4. The difference in structures and stability at low coverage depends on the stronger Cu–Fe interaction over the Cu–Cu interaction as well as the location of the adsorption sites. The adsorption energies do not correlate with the surface Fe and C ratios. Comparison among the most stable Fe(110), Fe3C(001), and Fe5C2(100) surfaces reveals that the Fe(110) surface has higher Cu affinity than the Fe3C(001) and Fe5C2(100) surfaces; and the carbide surfaces have close Cu affinities; in a...

Water adsorption and dissociation on the Fe(100) surface at different coverages have been calculated using density functional theory methods and ab initio thermodynamics. For the adsorption of (H2O)n clusters on the (3 × 4) Fe(100) surface, the adsorption energy is contributed by direct H2O–Fe interaction and hydrogen bonding. For n = 1–3, direct H2O–Fe interaction is dominant, and hydrogen bonding becomes more important for n = 4–5. For n = 6–8 and 12, structurally different adsorption configurations have very close energies. Monomeric H2O dissociation is more favored on the clean Fe(100) surface than that on H2O or OH precovered surfaces. O-assisted H2O dissociation is favorable kinetically (O + H2O = 2OH), and further OH dissociation is roughly thermo-neutral. With the increase of surface O coverage (nO, n = 2–7), further H2O dissociation has similar potential energy surfaces, and H2 formation from surface adsorbed H atoms becomes easy, while the desorption energy is close to zero for n = 7. The calcul...

Spin-polarized density functional theory computations have been carried out to investigate the adsorption configurations of Cun (n = 1–7, 13) on the most stable Fe(110) and Fe3C(001) surfaces. On both surfaces the adsorbed Cun clusters favor aggregation over dispersion, and monolayer adsorption configurations are more favored thermodynamically than the two-layer adsorbed structures because of the stronger Fe–Cu interaction over the Cu–Cu bonding. On the basis of the computed adsorption energies the Fe(110) surface has stronger Cu affinity than the Fe3C(001) surface, in agreement with the experimental results. The Fe(110) surface also has stronger Cun aggregation energies and more pronounced charge transfer from surface to adsorbed Cun clusters than the Fe3C(001) surface. Different Cun growth modes have been discussed accordingly.

Spin-polarized density functional theory computations have been carried out to study the adsorption and dissociation of CO on clean as well as nCu-adsorbed and nCu-substituted Fe(100) surfaces (n = 1–3) at different coverage to explore the Cu promotion effect in CO activation. Increasing Cu content not only lowers CO dissociation energies but also increases CO dissociation barriers as well as making CO dissociation thermodynamically less favorable, and the clean Fe(100) surface is most active in CO adsorption and dissociation. The nCu-substituted Fe(100) surface can suppress CO adsorption and dissociation more strongly than the nCu-adsorbed Fe(100) surface. CO stretching frequencies at different coverages have been computed for assisting experimental investigations.

The rhodium-catalyzed hydroformylation of methyl oleate (MO) with new monodentate phosphoramidite ligands 1a–d is investigated here. The ligands are characterized by lactam rings of different size (four- to seven-membered rings). In mild conditions (synthesis gas pressure: 30 bar, 80 °C), the rhodium catalysts based on the P-azetidinone phosphoramidite 1a gave within 6 h complete conversion and produced mainly methyl 9- and 10-formylstearate (MFS) with 99% chemoselectivity. In the hydrolysis test, phosphoramidite 1a was also the most stable. This was additionally confirmed by density functional theory calculations.

CO adsorption structures and energetics on the iron (100), (110), (111), (210), (211), and (310) surfaces from the lowest coverage up to saturation have been computed using spin-polarized density functional theory and ab initio thermodynamics. It is found that different adsorption configurations on each of these surfaces at high coverage can coexist. The stepwise adsorption energies and dissociation barriers at different coverage reveal equilibriums between desorption and dissociation of adsorbed CO molecules. Only molecular CO adsorption is possible at very high coverage and only dissociative CO adsorption at very low coverage, whereas mixed molecular and dissociative CO adsorption becomes possible at medium coverage. The computed stable adsorption configurations and the respective C–O and Fe–C stretching frequencies as well as desorption temperatures on the (100), (110), and (111) surfaces agree very well with the available experimental data. Such agreements between theory and experiment validate our co...

In this work, the new organic–inorganic hybrid compound Ph4P[(V2O3)2(PhAsO3)4⊂F] (VAsF) has been prepared and characterized by single-crystal XRD and multinuclear magnetic resonance (1H, 19F, 31P, and 51V). Redox properties and thermal stability have been investigated by EPR, cyclic voltammetry, and thermal analysis in comparison to its Ph4P[(V2O3)2(PhPO3)4⊂F] (VPF) analogue. The VAsF cluster has a lower redox potential and higher electrochemical stability in solution, while it is thermally less stable in the solid state. Density functional theory (DFT) calculations showed that the difference in the redox potential is due to the different electron affinities of VPF and VAsF. With this approach of modifying the type of the ligand of the molecular vanadium cage, we hope to enhance the utility of such compounds as building blocks for the design of new hybrid materials with desirable properties.

Hydrogen adsorption on the primarily exposed (001), (100), (101), and (201) surfaces of the hexagonal Mo2C phase at different coverage has been investigated at the level of density functional theory and using ab initio thermodynamics. On the Mo-terminated (001) and (100) as well as mixed Mo/C-terminated (101) and (201) surfaces, dissociative H2 adsorption is favored both kinetically and thermodynamically. At high coverage, each surface can have several types of adsorption configurations coexisting, and these types are different from surface to surface. The stable coverage as a function of temperature and partial pressure provides useful information not only for surface science studies at ultrahigh vacuum condition but also for practical applications at high temperature and pressure in monitoring reactions. The differences in the adsorbed H atom numbers and energies of these surfaces indicate their different potential hydrotreating abilities. The relationship between surface stability and stable hydrogen c...

Hydrogen adsorption structures and energetics on the (100), (110), (111), (210), (211), (310), and (321) iron surfaces up to saturation have been computed using spin-polarized density functional theory and ab initio thermodynamics. The computed hydrogen desorption temperatures and energies on the (100), (110), (111), and (211) surfaces as well as the Fe–H binding energies on the (110) and (111) surfaces agree well with the available experimental data. At typical hydrogen reduction temperature (675 K), the mainly exposed (110) and (310) facets represent the active surfaces, as supported by the transmission electron microscopy study. Our results offer an example of investigating and understanding surface structures and active facets of heterogeneous catalysts under experimental conditions.

CO adsorption and dissociation on the Mo and C terminations of the orthorhombic Mo2C(100) surface at different coverage were systematically investigated on the basis of density functional theory. On the Mo termination, only molecular adsorption is likely for nCO = 9–16. Mixed molecular and dissociative adsorption becomes possible for nCO = 8, while only dissociative adsorption is favorable for nCO = 1–7. This indicates the coverage-dependent CO dissociation and equilibrium between dissociation and desorption. On the C termination, there is no dissociative adsorption, and only molecular adsorption is favorable at all coverages (nCO = 1–16). The computed CO stretching frequencies as well as the predicted desorption states from ab initio thermodynamic analysis agree well with the available experimental findings. The stable coverage as a function of temperature and partial pressure provides useful information not only for surface science studies at ultrahigh vacuum conditions but also for practical applicatio...

CO activation on Fe(100) at different coverage was systematically computed on the basis of spin-polarized density functional theory. At the saturated coverage (11CO) on a p(3 × 4) surface size (24 exposed Fe atoms), top (1CO), bridge (3CO) and 4-fold hollow (7CO) adsorption configurations coexist. The stepwise adsorption energies and dissociation barriers at different coverage reveal equilibriums between desorption and dissociation of adsorbed CO molecules. It is found that only molecular adsorption is likely for nCO = 8–11, and mixed molecular and dissociative adsorption becomes possible for nCO = 5–7, while only dissociative adsorption is favorable for nCO = 1–4. The computed CO adsorption configurations and stretching frequencies as well as desorption temperatures from ab initio thermodynamic analysis agree well with the available experimental data.

Acrolein hydrogenation via allyl alcohol, propanal, and enol into propanol on the Ni(111) surface has been investigated using the spin-polarized periodic density functional theory method. On the basis of the computed adsorption energies and effective hydrogenation barriers, acrolein hydrogenation into propanal and allyl alcohol obeys the Langmuir–Hinshelwood mechanism and propanal formation is more favored kinetically and thermodynamically than allyl alcohol formation. Hydrogenation of propanal and allyl alcohol should follow the Eley–Rideal mechanism. The adsorption energies of acrolein, allyl alcohol, and propanal along with the partial hydrogenation selectivity on Ni, Au, Ag, and Pt catalysts have been compared and discussed.

The novel Co(I)-complex [CpCNCo(COD)] (CpCN = η5-(C5H4CMe2CH2CN), COD = 1,5-cyclooctadiene; 3) with a substituted cyclopentadienyl ligand containing a pendant nitrile moiety has been synthesized an...

The reaction mechanisms and promoting effect in the water gas shift reaction on (Fe, Co, Ni)-MoS2 have been computed at the level of density functional theory. The Mo-edge with 25% M substitution a...

For understanding the catalytic activity of Fe3O4-supported gold catalysts, the adsorption structures and energies of a single Au atom on the six terminations of the Fe3O4(111) surface have been computed at the level of density functional theory (GGA+U). For the most stable adsorption configurations, correlation has been found between the surface stability and the Au atom adsorption energy; that is, the more stable the surface, the lower the Au atom adsorption energy. It is also found that the adsorbed Au atom is reduced and has a negative charge on the iron-terminated surfaces, whereas it is oxidized and has a positive charge on the oxygen-terminated surfaces, and the latter is in agreement with the experimental observation. No correlation between the transferred charge and the adsorption energy has been found. Regarding the experimentally observed oxidation of gold nanoparticles on the iron oxide surface, it is possible to produce an oxygen-terminated surface for gold adsorption by synthetic tuning.