The nature of the electronic ground state of M<sub>2</sub>C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes

García-Romeral, Néstor; Morales-García, Ángel; Viñes, Francesc; de P. R. Moreira, Ibério; Illas, Francesc

doi:10.1039/d3cp04402e

Cited by 3 publications

(2 citation statements)

References 79 publications

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“…The lattice constants of W 2 C MXenes are calculated to be a = b = 2.83 Å, and the W-C bond length is found to be 2.126 Å, which is in excellent agreement with the previously reported results (Lattice constant a = b = 2.84 Å, and W-C bond length 2.130 Å) [ 27 , 34 ]. In addition, the formation energy of W 2 C, W 3 C 2 , and W 4 C 3 MXenes is calculated to be −3.48, −3.35, and −3.33 eV (see Table S1 ), respectively, indicating their strong thermodynamic stability [ 25 ]. All of these indicate the reliability of the WC-MXene models and calculation methods.…”

Section: Resultsmentioning

confidence: 99%

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First Principles Study of the Structure–Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries

Zhu,

Wang,

Liu

et al. 2024

Nanomaterials

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Li-O2 batteries are considered a highly promising energy storage solution. However, their practical implementation is hindered by the sluggish kinetics of the oxygen reduction (ORR) and oxygen evolution (OER) reactions at cathodes during discharging and charging, respectively. In this work, we investigated the catalytic performance of Wn+1Cn and Wn+1CnO2 MXenes (n = 1, 2, and 3) as cathodes for Li-O2 batteries using first principles calculations. Both Wn+1Cn and Wn+1CnO2 MXenes show high conductivity, and their conductivity is further enhanced with increasing atomic layers, as reflected by the elevated density of states at the Fermi level. The oxygen functionalization can change the electronic properties of WC MXenes from the electrophilic W surface of Wn+1Cn to the nucleophilic O surface of Wn+1CnO2, which is beneficial for the activation of the Li-O bond, and thus promotes the Li+ deintercalation during the charge–discharge process. On both Wn+1Cn and Wn+1CnO2, the rate-determining step (RDS) of ORR is the formation of the (Li2O)2* product, while the RDS of OER is the LiO2* decomposition. The overpotentials of ORR and OER are positively linearly correlated with the adsorption energy of the RDS LixO2* intermediates. By lowering the energy band center, the oxygen functionalization and increasing atomic layers can effectively reduce the adsorption strength of the LixO2* intermediates, thereby reducing the ORR and OER overpotentials. The W4C3O2 MXene shows immense potential as a cathode catalyst for Li-O2 batteries due to its outstanding conductivity and super-low ORR, OER, and total overpotentials (0.25, 0.38, and 0.63 V).

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Section: Resultsmentioning

confidence: 99%

“…(b) The W x C y materials have been proven Pt-like catalytic features in many electrochemical reactions, such as ORR and OER [ 24 ]. (c) WC MXenes have a metallic nature, high charge capacity, and low Li + diffusion barrier, facilitating the rapid deintercalation of Li + during the charge–discharge process [ 25 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

First Principles Study of the Structure–Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries

Zhu,

Wang,

Liu

et al. 2024

Nanomaterials

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Ionic liquids intercalation in titanium carbide MXenes: A first‐principles investigation

Zhang,

Jiang,

Zhou

et al. 2024

J Comput Chem

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Herein, we present a density functional theory with dispersion correction (DFT‐D) calculations that focus on the intercalation of ionic liquids (ILs) electrolytes into the two‐dimensional (2D) Ti3C2Tx MXenes. These ILs include the cation 1‐ethyl‐3‐methylimidazolium (Emim+), accompanied by three distinct anions: bis(trifluoromethylsulfonyl)imide (TFSA−), (fluorosulfonyl)imide (FSA−) and fluorosulfonyl(trifluoromethanesulfonyl)imide (FTFSA−). By altering the surface termination elements, we explore the intricate geometries of IL intercalation in neutral, negative, and positive pore systems. Accurate estimation of charge transfer is achieved through five population analysis models, such as Hirshfeld, Hirshfeld‐I, DDEC6 (density derived electrostatic and chemical), Bader, and VDD (voronoi deformation density) charges. In this work, we recommend the DDEC6 and Hirshfeld‐I charge models, as they offer moderate values and exhibit reasonable trends. The investigation, aimed at visualizing non‐covalent interactions, elucidates the role of cation‐MXene and anion‐MXene interactions in governing the intercalation phenomenon of ionic liquids within MXenes. The magnitude of this role depends on two factors: the specific arrangement of the cation, and the nature of the anionic species involved in the process.

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Investigation of work function and quantum capacitance of OH-terminated MXenes as supercapacitor electrodes: A theoretical perspective

Yin,

Li,

Zhang

et al. 2024

FlatChem

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The nature of the electronic ground state of M₂C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes

Abstract: A systematic computational study is presented aimed at accurately describing the electronic ground state nature and properties of M2C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes.

Cited by 3 publications

References 79 publications

First Principles Study of the Structure–Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries

First Principles Study of the Structure–Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries

Ionic liquids intercalation in titanium carbide MXenes: A first‐principles investigation

Investigation of work function and quantum capacitance of OH-terminated MXenes as supercapacitor electrodes: A theoretical perspective

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The nature of the electronic ground state of M2C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes

Abstract: A systematic computational study is presented aimed at accurately describing the electronic ground state nature and properties of M2C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes.

Cited by 3 publications

References 79 publications

First Principles Study of the Structure–Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries

First Principles Study of the Structure–Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries

Ionic liquids intercalation in titanium carbide MXenes: A first‐principles investigation

Investigation of work function and quantum capacitance of OH-terminated MXenes as supercapacitor electrodes: A theoretical perspective

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The nature of the electronic ground state of M₂C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes