Ethylene carbonate adsorption on the major surfaces of lithium manganese oxide Li1−xMn2O4spinel (0.000 &lt;x&lt; 0.375): a DFT+U-D3 study

Ramogayana, Brian; Santos‐Carballal, David; Aparicio, Pablo A.; Quesne, Matthew G.; Maenetja, Khomotso P.; Ngoepe, Phuti E.; Leeuw, Nora H. de

doi:10.1039/c9cp05658k

Cited by 21 publications

(21 citation statements)

References 76 publications

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“…We have used the Vienna Ab initio Simulation Package (VASP) [30][31][32][33] [34,35]. Long-range dispersion interactions were included using the semi-empirical method of Grimme, with the Becke-Johnson damping [D3-(BJ)] [36,37], which is required for the realistic simulation of the bulk and surface properties of several different materials [9,[38][39][40][41][42][43][44][45]. The inner electron included up to the 3s level for Cu; 2p level for Ti; 4f level for Pt; 4s level for Pd and Ag; and 1s level for O, C and N, and were described by the projector augmented wave (PAW) method [46,47], whereas the electron of the H atom was treated as valence.…”

Section: Computationalmentioning

confidence: 99%

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

et al. 2021

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Heterojunctions are used in solar cells and optoelectronics applications owing to their excellent electrical and structural properties. Recently, these energy-efficient systems have also been employed as sensors to distinguish between individual gases within mixtures. Through a simple and versatile functionalization approach using noble metal nanoparticles, the sensing properties of heterojunctions can be controlled at the nanoscopic scale. This work reports the nanoparticle surface functionalization of the TiO2/CuO/Cu2O mixed oxide heterostructures, where the gas sensing selectivity of the material is tuned to achieve versatile sensors with ultra-low power consumption. Functionalization with Ag or AgPt-nanoclusters (5-15 nm diameter), changed the selectivity from ethanol to butanol vapour. The Pdnanocluster functionalization shifts the selectivity from the alcohols to hydrogen. The fabricated sensors show excellent low power consumption below 1 nW. To gain insight into the selectivity mechanism, density functional theory (DFT) calculations were carried out to simulate the adsorption of H2, C2H5OH and n-C4H9OH at the noble metal nanoparticle decorated ternary heterostructure interface. These calculations also show a decrease in the work function by ~2.6 eV with respect to the pristine ternary heterojunctions. This work lays the foundation for the production of a very versatile array of sensors of ultra-low power consumption with applications for the detection of individual gases in a mixture.

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Section: Computationalmentioning

confidence: 99%

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

et al. 2021

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“…The electronic density optimization was stopped when the total energy difference between two consecutive self-consistent loop steps was below 10 –5 eV. In order to accurately describe the long-range dispersion interactions, we have adopted the empirical correction method with the Becke–Johnson damping presented by Grimme and co-workers [D3−(BJ)], , which has been proven reliable in the simulation of surface properties of various materials. ,− …”

Section: Computational Methodsmentioning

confidence: 99%

Catalytic Conversion of CO and H₂ into Hydrocarbons on the Cobalt Co(111) Surface: Implications for the Fischer–Tropsch Process

2021

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The Fischer−Tropsch (FT) process consists of the reaction of a synthesis gas (syngas) mixture containing carbon monoxide (CO) and hydrogen (H 2 ), which are polymerized into liquid hydrocarbon chains, often using a cobalt catalyst, although the mechanistic pathway is not yet fully understood. Here, we have employed unrestricted density functional theory calculations with a Hubbard Hamiltonian and long-range dispersion corrections [DFT+U−D3−(BJ)] to investigate the reaction of syngas and the selectivity toward the hydrocarbons formed on the cobalt Co(111) surface. The single CO and dissociated H 2 molecules prefer to adsorb at two different types of trigonal surface sites, and we discuss how the interatomic distances, fundamental vibrational modes, charge transfers, surface-free energies, and work functions are modified by the adsorbates. The coadsorption of the syngas molecules in close proximity provides enough energy for the system to cross the saddle points on the minimum energy pathway (MEP), leading to the catalytic hydrogenolysis of the C−O bond. The adsorbed CO, alongside the intermediates CH and OH, are further stabilized when the ratio of equilibrium coverage (C) is C H /C CO,CH,OH > 6:1 under the temperature conditions required for the FT process. We propose several mechanistic pathways to account for the formation of ethane (C 2 H 6 ), as a model for long-chain hydrocarbons, as well as methane (CH 4 ) which is an undesirable product. The MEPs for these processes show that the coupling of the C−C bond followed by hydrogenation is the most favorable process, which takes precedence over the production of CH 4 . The termination reaction suggests that water (H 2 O) remains weakly physisorbed to the surface, allowing the reutilization of its catalytic site. The simulated fundamental vibrational frequencies and scanning tunneling microscopy images of the surface-bound intermediates are in agreement with the available experimental data. Our findings are important in the interpretation of the elementary steps of the FT process on the Co(111) surface.

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“…62−64 Compared to other organic solvents, EC has boiling and melting points, which are approximately 248 and 36.4 °C, respectively. 65 In our previous study, 66 we employed DFT calculations with a Hubbard Hamiltonian and long-range dispersion corrections to study the adsorption of EC onto the low-Miller-index surfaces of LiMn 2 O 4 , where we found that the EC weakly adsorbed on the Mn/Li sites of the spinel surfaces via the carbonyl or ethereal oxygen, thus allowing the molecule to detach easily to expose the (111) surface. However, the reactivity of EC with the coating material α-Al 2 O 3 is equally important but not yet fully understood.…”

Section: Introductionmentioning

confidence: 99%

“…Similar results were found in our previous study, where we investigated the EC adsorption on the major surfaces of the LiMn 2 O 4 spinel. 66 The EC molecule gained small charges of −0.094 and −0.071 e − when it was placed in parallel and perpendicular modes onto the surface. As we increased the surface coverage to θ = 0.50, the charge transfer remained constant in both orientations.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Study of Ethylene Carbonate Adsorption on the (0001) Surface of Aluminum Oxide α-Al₂O₃

et al. 2021

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Surface coating is one of the techniques used to improve the electrochemical performance and enhance the resistance against decomposition of cathode materials in lithium-ion batteries. Despite several experimental studies addressing the surface coating of secondary Li-ion batteries using α-Al2O3, the reactivity of the material toward the electrolyte components is not yet fully understood. Here, we have employed calculations based on the density functional theory to investigate the adsorption of the organic solvent ethylene carbonate (EC) on the major α-Al2O3(0001) surface. During adsorption of a single EC molecule, it was found that it prefers to bind parallel to the surface through its carboxyl oxygen. As the surface coverage (θ) was increased up to a monolayer, we observed larger adsorption energies per EC molecule (E ads/N EC) for parallel interactions and a reduction for perpendicular interactions. We also noted that increasing the surface coverage with both parallel and perpendicularly interacting EC molecules led to a decrease of the surface free energies and hence increased stability of the α-Al2O3(0001) surface. Despite the larger E ads/N EC observed when the molecule was placed parallel to the surface, minimal charge transfer was calculated for single EC interactions and at higher surface coverages. The simulated scanning tunneling microscopy images are also presented for a clean corundum α-Al2O3 surface and after adsorption with different coverages of parallel and perpendicularly placed EC molecules.

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Ethylene carbonate adsorption on the major surfaces of lithium manganese oxide Li_1−xMn₂O₄spinel (0.000 <x< 0.375): a DFT+U-D3 study

Abstract: Surface reactivity of LiMn2O4 spinel cathode material towards ethylene carbonate (EC) electrolyte solvent using density functional theory (DFT).

Cited by 21 publications

References 76 publications

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

Catalytic Conversion of CO and H₂ into Hydrocarbons on the Cobalt Co(111) Surface: Implications for the Fischer–Tropsch Process

Density Functional Theory Study of Ethylene Carbonate Adsorption on the (0001) Surface of Aluminum Oxide α-Al₂O₃

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Ethylene carbonate adsorption on the major surfaces of lithium manganese oxide Li1−xMn2O4spinel (0.000 <x< 0.375): a DFT+U-D3 study

Abstract: Surface reactivity of LiMn2O4 spinel cathode material towards ethylene carbonate (EC) electrolyte solvent using density functional theory (DFT).

Cited by 21 publications

References 76 publications

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

Catalytic Conversion of CO and H2 into Hydrocarbons on the Cobalt Co(111) Surface: Implications for the Fischer–Tropsch Process

Density Functional Theory Study of Ethylene Carbonate Adsorption on the (0001) Surface of Aluminum Oxide α-Al2O3

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Ethylene carbonate adsorption on the major surfaces of lithium manganese oxide Li_1−xMn₂O₄spinel (0.000 <x< 0.375): a DFT+U-D3 study

Catalytic Conversion of CO and H₂ into Hydrocarbons on the Cobalt Co(111) Surface: Implications for the Fischer–Tropsch Process

Density Functional Theory Study of Ethylene Carbonate Adsorption on the (0001) Surface of Aluminum Oxide α-Al₂O₃