A theoretical study of the effects of the charge state and size of gold clusters on the adsorption and dissociation of H2

Kang, Guo‐Jun; Chen, Zhao‐Xu; Li, Zhe; He, Xiang

doi:10.1063/1.3061462

Cited by 42 publications

(42 citation statements)

References 33 publications

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“…Figures 6a and 6b demonstrate that H 2 can dissociate on the neutral Au 3 and Au 4 clusters with a very low barrier, for both T = 0 K and T = 298.15 K. However, for n = 2 and 5−11 the energy of the TS state is considerably larger than the binding Therefore, it is likely that molecular H 2 will desorb from Au 2 and Au 5−11 , rather than dissociate. On the basis of PW91/def2-TZVPP DFT calculations, 56 Kang et al suggested that H 2 dissociation is also feasible on the Au 5 cluster because the binding energy of H 2 to Au 5 is larger than the dissociation barrier. However, according to our calculations with the use of PBE functional with DZP basis set, the barrier is larger than the change in free energy upon H 2 adsorption on Au 5 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Reactivity of Gold Clusters in the Regime of Structural Fluxionality

et al. 2015

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This work present results of a systematic investigation of adsorption and dissociation of H 2 on the neutral, positively, and negatively charged gold clusters Au n q (n = 2−11; q = 0, ±1) using the global reaction route mapping (GRRM) technique combined with the anharmonic downward distortion following (ADDF) and the artificial forceinduced reaction (AFIR) methods. An exhaustive search for H 2 dissociation pathways is performed not only on the most stable cluster structures but also on the large number of low-energy isomers, allowing structural transformations between them. The present strategy can automatically identify the structure-dependent lowest transition states (TS) for H 2 dissociation with a systematic procedure in the regime of the structural fluxionality of gold clusters at finite temperature. Temperature effects, cluster isomerization, and influence of the charge state of gold clusters on H 2 adsorption and dissociation are studied. It is demonstrated that the most stable structures of the gold clusters are not always highly reactive, and an ensemble of isomeric structures must be taken into account for adequate description of the reaction rates at finite temperatures. The proposed approach can serve as a promising tool for a systematic analysis and prediction of reactivity of small metal clusters. ■ INTRODUCTIONGold is one of the most intensively studied elements in nanocatalysis due to its unique catalytic activity and selectivity emerging at nanoscale even at room temperatures. 1,2 This feature makes gold a very promising catalyst for the chemical industry and environmental applications. 3,4 The most explored type of catalytic reactions with gold nanoparticles are reactions of oxidation and epoxidation by molecular oxygen, 1,2,5−15 with a strong focus on oxidation of carbon monoxide 1,2,4,9,16−24 as a most simple model case, allowing us to test various approaches and theories. Heterogeneously catalyzed hydrogenation is another type of reaction where gold nanoparticles have shown their great potential as catalysts. 11,25,26 It has been shown that gold nanoparticles supported on the surfaces of some metal oxides can effectively catalyze selective hydrogenation of several classes of organic molecules, including unsaturated aldehydes, ketones, hydrocarbons, and nitro compounds. 26−36 Moreover, gold nanoparticles are very selective for the direct formation of hydrogen peroxide from H 2 and O 2 mixtures. 8,37−40 Dissociative adsorption of molecular hydrogen on gold nanoparticles is the first and one of the most important steps in heterogeneously catalyzed hydrogenation reactions because often it determines the reaction rate. It has been demonstrated that H 2 does not bind to the clean gold bulk surface 41 but adsorbs and dissociates on the supported 11,26,42−49 and free 50−60 gold nanoparticles.Theoretical calculations performed by Corma and coworkers demonstrate that the active sites for H 2 dissociation are usually located at low-coordinated corner or edge positions on a cluster surface and do not dir...

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Section: ■ Results and Discussionmentioning

confidence: 99%

Reactivity of Gold Clusters in the Regime of Structural Fluxionality

et al. 2015

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“…These small clusters are selected because Au n clusters with n =3-5 are found most active. 28 We examined the adsorption of ethylene and formaldehyde on these clusters. Our results demonstrate that ethylene and formaldehyde can interact moderately strongly with Au clusters with binding energies higher than those previously reported.…”

Section: Introductionmentioning

confidence: 99%

Theoretical studies of the interactions of ethylene and formaldehyde with gold clusters

Kang

Chen

2009

The Journal of Chemical Physics

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We studied the adsorption of C(2)H(4) and CH(2)O on the gold clusters Au(n) (n = 1-5) in various adsorption modes using density functional theory PW91 functional. We found that the binding energies of pi-C(2)H(4) and pi and O-sigma modes of CH(2)O increase first and then decrease with the cluster size. Natural bonding orbital (NBO) analyses reveal that the donor-acceptor interaction plays an important role in these adsorption complexes and there is a nice linear relationship between the calculated binding energy and the stabilization energy estimated with second-order perturbation theory in the framework of NBO analysis. It is demonstrated that the bonding interaction between adsorbates and clusters follows the di-sigma > pi > O-sigma mode. However, due to adsorption induced structural deformation of adsorbates and clusters, the binding energies of different adsorption modes are comparable. It is shown that C(2)H(4) interacts more strongly with the clusters than CH(2)O does and that the previously assigned adsorption mode of C(2)H(4) on Au/MgO may not be the pi modes, but the C-sigma configuration.

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“…It is well known that adsorption simultaneously results in the structural deformation of both the adsorbate and the cluster, which will destabilize the adsorption system. Previously [22,35] we have adopted E int defined in (1) to estimate the interaction between an adsorbate and a cluster:…”

Section: Methodsmentioning

confidence: 99%

Acrolein Adsorption on Gold Clusters, A Theoretical Study of Conjugation Effect on C=C and C=O Interaction with Au Clusters

Kang

Chen

2011

Catal Lett

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We studied acrolein (AC) adsorption on gold clusters Au n (n = 1-5) using density functional theory. It is demonstrated that conjugation effect reduces the adsorbatesubstrate interaction through p-(C=C), p-(C=O) and di-r-(C=O) modes whereas it facilitates the di-r-(C=C) and the r-O configurations. Analysis reveals that in p-(C=C) and p-(C=O) modes acrolein uses the HOMO-1 orbital to interact with the clusters while in r-O mode the HOMO of AC plays the role. For di-r-(C=C), di-r-(C, O) and di-(C=O), the HOMO orbital of the cluster donates electrons to acrolein. Acrolein adsorption through the C=C bond is more favorable than that via the C=O group, which explains why the yields of C=C hydrogenation is higher than that of C=O reduction.

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A theoretical study of the effects of the charge state and size of gold clusters on the adsorption and dissociation of H2

Cited by 42 publications

References 33 publications

Reactivity of Gold Clusters in the Regime of Structural Fluxionality

Reactivity of Gold Clusters in the Regime of Structural Fluxionality

Theoretical studies of the interactions of ethylene and formaldehyde with gold clusters

Acrolein Adsorption on Gold Clusters, A Theoretical Study of Conjugation Effect on C=C and C=O Interaction with Au Clusters

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