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M. Pernisek

Bio: M. Pernisek is an academic researcher from Artois University. The author has contributed to research in topics: Intercalation (chemistry) & Covalent bond. The author has an hindex of 2, co-authored 2 publications receiving 43 citations.

Papers
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Adlane Sayede1, T. Amriou1, M. Pernisek1, B. Khelifa1, C. Mathieu1 
TL;DR: In this paper, the structure and electronic properties of the α-MoO3 were studied with periodic LAPW calculations with the results in excellent agreement with the reported experimental pseudo-cubic results.

41 citations

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TL;DR: In this paper, the LCAO-Hartree-Fock method was applied to the V 2 O 5 (001) surface to investigate the lithium intercalation effects on the surface of the V2O 5 surface.

5 citations


Cited by
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TL;DR: The large work function of MoO3 is due to its closed shall character and the dipole layer created by planes of terminal O1 oxygen sites which lower the electrostatic potential of the inner Mo-O units as mentioned in this paper.
Abstract: The large work function of MoO3 of 6.6 eV is due to its closed shall character and the dipole layer created by planes of terminal O1 oxygen sites which lower the electrostatic potential of the inner Mo-O units. These O1 sites arise from the high stoichiometry of MoO3. The O vacancy is most stable at the 2-fold O2 site. It is a shallow donor and has a small formation energy in the O poor limit so that MoO3 easily becomes a degenerate semiconductor.

158 citations

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TL;DR: In this paper, high uniform MoO3 nanoparticles, created using a unique hot-wire chemical vapor deposition (HWCVD) system, were studied as active material for negative electrodes in high-energy lithium ion batteries.

132 citations

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TL;DR: In this article, the authors present a review of the combined theoretical and experimental studies on hydrogen spillover mechanisms in solid-state materials where, for the first time, the complete mechanisms that dictate hydrogen spilloff processes in transition metal oxides and nanostructured graphitic carbon-based materials have been revealed.
Abstract: Hydrogen spillover has emerged as a possible technique for achieving high-density hydrogen storage at near-ambient conditions in lightweight, solid-state materials. We present a brief review of our combined theoretical and experimental studies on hydrogen spillover mechanisms in solid-state materials where, for the first time, the complete mechanisms that dictate hydrogen spillover processes in transition metal oxides and nanostructured graphitic carbon-based materials have been revealed. The spillover process is broken into three primary steps: (1) dissociative chemisorption of gaseous H2 on a transition metal catalyst; (2) migration of H atoms from the catalyst to the substrate and (3) diffusion of H atoms on substrate surfaces and/or in the bulk materials. In our theoretical studies, the platinum catalyst is modeled with a small Pt cluster and the catalytic activity of the cluster is examined at full H atom saturation to account for the essentially constant, high H2 pressures used in experimental studies of hydrogen spillover. Subsequently, the energetic profiles associated with H atom migrations from the catalyst to the substrates and H atom diffusion in the substrates are mapped out by calculating the minimum energy pathways. It is observed that the spillover mechanisms for the transition metal oxides and graphitic carbon-based materials are very different. Hydrogen spillover in the transition metal oxides is moderated by massive, nascent hydrogen bonding networks in the crystalline lattice, while H atom diffusion on the nanostructured graphitic carbon materials is governed mostly by physisorption of H atoms. The effects of carbon material surface curvature on the hydrogen spillover as well as on hydrogen desorption dynamics are also discussed. The proposed hydrogen spillover mechanism in carbon-based materials is consistent with our experimental observations of the solid-state catalytic hydrogenation/dehydrogenation of coronene.

128 citations

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TL;DR: In this article, the absorption, diffusion, and desorption of atomic hydrogen in layered orthorhombic molybdenum trioxide (α-MoO3) was investigated using density functional theory.
Abstract: The absorption, diffusion, and desorption of atomic hydrogen in layered orthorhombic molybdenum trioxide (α-MoO3) was investigated using density functional theory. Hydrogen atoms are absorbed in bulk α-MoO3 to form the hydrogen molybdenum bronze HxMoO3 (x = 0.25, 0.5, 0.75, 1, 1.25, and 1.5). The semiconductor band gap of bulk α-MoO3 shifts to metallic upon hydrogen bronze formation at the H atom loadings selected in the present study. The hydrogen atoms become protonic when coordinated to oxygen, which gives rise to a charge reduction on the Mo atoms adjacent to the absorption sites. Hydrogen migration along a prescribed diffusion pathway in the lattice was found to be facile due to small energy barriers for H atom transfer between O atoms, facilitated by a hydrogen bonding network. The sequential hydrogen desorption from the bronze and the mechanisms of hydrogen spillover in α-MoO3 are also discussed.

122 citations

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TL;DR: In this paper, the exchange functional vdW-DF2 was used to model the electronic structure of layered molybdenum trioxide MoO3, in good agreement with experimental data.
Abstract: The electronic structure of layered molybdenum trioxide MoO3 is highly sensitive to changes in oxygen stoichiometry as Mo6+ has an empty 4d shell. Applications of MoO3 are responsive to small changes in vacancy concentration, with some functions relying on a narrow window of oxygen nonstoichiometry. Difficulties in analyzing the energetics of oxygen vacancies by computational methods stem from the inability to accurately model the layered structure of MoO3. One unit cell parameter is governed by long-range forces across the structural gaps, and these dispersed interactions are not well described by conventional density functional theory (DFT) methods. With the exchange functional vdW-DF2, we accurately model the structure, in good agreement with experimental data. This basis allows exploration of the effect of oxygen nonstoichiometry on the electronic structure and properties of the oxygen-deficient material. The layered structure efficiently screens the structural perturbations caused by oxygen vacancies...

82 citations