Oxygen-induced reconstruction of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mtext>Re</mml:mtext><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mn>10</mml:mn><mml:mover accent="true"><mml:mn>1</mml:mn><mml:mo stretchy="false">¯</mml:mo></mml:mover><mml:mn>0</mml:mn></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>studied by density functional theory

Kaghazchi, Payam; Jacob, Timo

doi:10.1103/physrevb.81.075431

Cited by 12 publications

(7 citation statements)

References 35 publications

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“…This is due to the stabilization of different O and N structures on (1010): For N adsorption, we found a zigzag arrangement of N on the Re(1010) surface. 34 Interestingly, such an overlayer, which has also been observed for O/Ru(1010), 36 does not form for O/Re(1010). 34 The morphology of nanoparticles is one of the key factors responsible for their catalytic behavior.…”

Section: Resultsmentioning

confidence: 81%

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Structure-activity relation of Re nanoparticles

Kaghazchi¹,

Jacob²

2012

Phys. Rev. B

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By combining density functional theory and thermodynamic considerations we determined the equilibrium shape of Re particles in contact with O 2 and N 2 environments. At low and intermediate coverages oxygen adsorption has a minor influence on the particle shape, while nitrogen adsorption leads to the stabilization of spherically shaped polyhedra with a large contribution from atomically rough faces. At very high coverages of O and N particles are perfect prisms consisting of low-index faces. By comparing these results with the experimental data for the activity of different Re surfaces we propose that the experimentally measured high initial activity of polycrystalline Re for ammonia synthesis might be due to the N-induced formation of high-index faces with a high density of low-coordinated atoms (roughening). Moreover, the measured decrease in the activity of polycrystalline Re at saturation coverage might be because of the N-induced formation of close-packed faces (smoothing). Our calculations suggest that adsorbate-induced roughening or smoothing of catalytic particles on the atomic scale is capable of controlling the activity of the catalysts.

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Section: Resultsmentioning

confidence: 81%

“…34 Interestingly, such an overlayer, which has also been observed for O/Ru(1010), 36 does not form for O/Re(1010). 34 The morphology of nanoparticles is one of the key factors responsible for their catalytic behavior. In the present work, we focus on ammonia synthesis on Re, being among the best catalysts for this reaction.…”

Section: Resultsmentioning

confidence: 81%

Structure-activity relation of Re nanoparticles

Kaghazchi¹,

Jacob²

2012

Phys. Rev. B

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“…The differential Gibbs free energy in eq. ( 3) can be replaced by DFT calculated total energies, which is discussed in Refs.. 39,41…”

Section: Theoretical Methodsmentioning

confidence: 99%

Molecular Precursor Induced Surface Reconstruction at Graphene/Pt(111) Interfaces

2015

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Inspired by experimental observations of Pt(111) surfaces reconstruction at the Pt/graphene (Gr) interfaces with ordered vacancy networks in the outermost Pt layer [e.g., Otero, G., et al. Phys. Rev. Lett. 2010, 105, 216102 ], the mechanism of the surface reconstruction is investigated by van der Waals corrected density functional theory in combination with particle-swarm optimization algorithm and ab initio atomistic thermodynamics. Our global structural search finds a more stable reconstructed structure than that which was reported before. With correction for vacancy formation energy, we demonstrate that the experimental observed surface reconstruction occurred at the earlier stages of graphene formation: (1) reconstruction occurred when C 60 adsorption (before decomposition to form graphene) for C 60 precursor or (2) reconstruction occurred when there were (partial) hydrogens remain in the hydrogenated precursors of C 2 H 4 and planar C 60 H 30 . The reason is attributed to the fact that the energy gain, from the strengthened Pt− C partial sp 3 −like bonding for C of C 60 or for C with partial H (than Pt−Gr bonding), compensates for the energy cost of formation surface vacancies and makes the reconstruction feasible, especially at elevated temperatures. In our predicted reconstructed structure Pt−C covalent bonds are formed that have a great impact on the adsorbed Gr electronic structures. INTRODUCTIONThe investigations of hybrid organic−metal interfaces are experiencing an explosive growth, 1−4 especially for epitaxial growth of graphene (Gr) layers on metal surfaces. Extraordinary properties such as ambipolar electric field effect, quantization of conductivity, and ultrahigh electron mobility of graphene are demonstrated, 5−7 which can be attributed to the unique electronic structure of graphene and its interaction with metal substrates. One of the practical needs is preparing graphene layers on metal surfaces with different thicknesses. 8,9 Although there are many applications for these systems, mechanisms of graphene−metal bonding at their interfaces in the atomic detail are far from a complete understanding. Different types of interactions coexist at graphene−metal interfaces, which include chemical bonding, van der Waals (vdW) interaction, Pauli repulsion, 10−13 and more often a combination of them. For metal substrates whose lattice constants match that of Gr, strong covalent interactions exist between Gr and metals, and strong interactions usually destroy the Dirac cone of Gr. 14,15 In the cases of Gr physically adsorbed on or ionically bonded with metal surfaces, the Dirac cone is preserved in the band structure, and the energy position of the Dirac cone relative to Fermi energy can be tuned by charge transfer. 16−18 Surface reconstruction at Gr/metal interfaces makes it a challenge to understand the Gr−metal contact mechanism. 19−21 Three questions remain to be answered: how is every atom arranged at the interface, can the reconstructed structure be energetically favored, and whether the metal surf...

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“…is the chemical potential of isolated H 2 molecule in the gas phase [31,32]. In regard to the Gibbs free energy of solid phase, it reads…”

Section: Mechanism Of Hydrogen Adsorption On Na 2 Nmentioning

confidence: 99%

Hydrogen adsorption behavior on AXenes Na₂N and K₂N: a first-principles study

Dong

Zhang

et al. 2022

Mater. Res. Express

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It is a consensus that the hydrogen economy has come to a standstill due to the lack of feasible hydrogen storage solutions, especially, the suitable hydrogen storage materials. In this work, the potential of a new kind of two-dimensional (2D) AXenes, Na2N and K22N, as hydrogen storage materials are evaluated by the first-principles calculations. In particular, we find that Na2N in T phase indicates a hydrogen storage capacity as high as 6.25 wt% with a desirable hydrogen adsorption energy of –0.167 eV per H2 molecule and a desorption temperature of 216 K, identifying T-phase Na2N to be a very promising reversible hydrogen storage material. In accordance to our results, H2–Na2N interaction causes H2 charge polarization, which is responsible for the moderate binding strength. In addition, Gibbs adsorption free energy reveals that the system will be more stable as more H2 molecules are loaded on the surface.

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Oxygen-induced reconstruction ofRe(101¯0)studied by density functional theory

Cited by 12 publications

References 35 publications

Structure-activity relation of Re nanoparticles

Structure-activity relation of Re nanoparticles

Molecular Precursor Induced Surface Reconstruction at Graphene/Pt(111) Interfaces

Hydrogen adsorption behavior on AXenes Na₂N and K₂N: a first-principles study

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Oxygen-induced reconstruction ofRe(101¯0)studied by density functional theory

Cited by 12 publications

References 35 publications

Structure-activity relation of Re nanoparticles

Structure-activity relation of Re nanoparticles

Molecular Precursor Induced Surface Reconstruction at Graphene/Pt(111) Interfaces

Hydrogen adsorption behavior on AXenes Na2N and K2N: a first-principles study

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Hydrogen adsorption behavior on AXenes Na₂N and K₂N: a first-principles study