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Inhibiting the shuttle effect in sodium-sulfur batteries using Mo2CT2(T = S, O) MXenes: A DFT investigation
(2026-03-30)
Udomkijmongkol, Anan
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Ruttanapunt, Piyaphat
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Thasitha, Sirinee
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Ounrit, Iyarat
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Khammuang, Satchakorn
The rising demand for electrification has highlighted sodium–sulfur (Na–S) batteries as a promising energy-storage technology due to their high theoretical capacity, abundant materials, and low cost. However, their performance is limited by polysulfide dissolution, or the shuttle effect, which slows redox kinetics and accelerates capacity fading. This study employs the DFT method to investigate Mo<inf>2</inf>CT<inf>2</inf> (T = S, O) MXenes in 1T and 2H phases as potential anchoring materials for sulfur cathodes. All Mo<inf>2</inf>CT<inf>2</inf> structures effectively adsorb sodium polysulfides (Na<inf>2</inf>S<inf>n</inf>), demonstrating higher adsorption strength than commercial electrolytes and effectively suppressing the shuttle effect. Structural phase notably affects Na<inf>2</inf>S<inf>n</inf> adsorption on Mo<inf>2</inf>CS<inf>2</inf>, while its influence is minor for Mo<inf>2</inf>CO<inf>2</inf>. Higher Na<inf>2</inf>S<inf>n</inf>-Mo<inf>2</inf>CO<inf>2</inf> interaction arises from greater charge transfer from Na to O atom driven by higher electronegativity difference. Among the candidates, 2H-Mo<inf>2</inf>CS<inf>2</inf> and 1T-Mo<inf>2</inf>CO<inf>2</inf> exhibit higher binding energies than its counterpart and maintain metallic conductivity after Na<inf>2</inf>S<inf>n</inf> adsorption, benefiting electron transport. Gibbs free energy calculations indicate more favorable sulfur reduction pathways on Mo<inf>2</inf>CT<inf>2</inf> surfaces, along with reduced energy barriers for Na<inf>2</inf>S oxidation. Overall, Mo<inf>2</inf>CT<inf>2</inf> MXenes exhibit strong anchoring capability and catalytic activity, making them promising materials for mitigating the shuttle effect and enhancing electrochemical performance in Na–S batteries.
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Structural stabilities, elastic property, and robust topological phases in Janus MoWCO2MXene from first-principles investigation
(2026-02-25)
Thasitha, Sirinee
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Tsuppayakorn-aek, Prutthipong
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Kaewmaraya, Thanayut
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Hussain, Tanveer
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Bovornratanaraks, Thiti
Two-dimensional (2D) topological materials have attracted considerable interest because of their potential applications in next-generation quantum and spintronic devices. In this work, we systematically investigate the structural, mechanical, and electronic properties of Janus MoWCO<inf>2</inf> MXene using first-principles density functional theory (DFT) calculations, both with and without spin–orbit coupling (SOC). The energetically favored O-terminated configurations are examined in detail, revealing that the 2H phase exhibits higher thermodynamic, mechanical, and dynamical stability than the 1T phase. In the absence of SOC, both phases display metallic behavior. Upon inclusion of SOC, a band inversion emerges at the Γ point. In particular, SOC opens a narrow band gap of approximately 0.10 eV in the 2H phase, whereas the 1T phase remains gapless and exhibits semimetallic characteristics. Topological analysis based on helical edge states and Z<inf>2</inf> invariants indicates that 2H-MoWCO<inf>2</inf> is a strong topological insulator candidate, while 1T-MoWCO<inf>2</inf> can be classified as a topological semimetal candidate. These findings suggest that Janus MoWCO<inf>2</inf> MXene represents a promising two-dimensional platform for exploring SOC-driven topological phases and related quantum phenomena.
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Unveiling the potential of Mo2C and Mo2CO2MXenes for Na-ion batteries: An ab initio study
(2026-01-01)
Khammuang, Satchakorn
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Kaewmaraya, Thanayut
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Hussain, Tanveer
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Kotmool, Komsilp
This study employs density functional theory (DFT) calculations to investigate the potential of Mo<inf>2</inf>C and Mo<inf>2</inf>CO<inf>2</inf>MXenes as promising anode material candidates for Na-ion batteries under varying biaxial strains. The findings indicate that O-termination significantly enhances the Na adsorption energy compared to bare Mo<inf>2</inf>C, due to a stronger O-Na interaction. Under compressive strain, the diffusion energy barrier decreases while it increases under tensile strain for both forms of Mo<inf>2</inf>C-based MXenes. Ab initio molecular dynamics (AIMD) simulations at 300 K, which verify the thermal stabilities of both calculated MXenes, suggest their maximum theoretical capacities at operational temperatures, calculated to be 131.43 mAh/g for Mo<inf>2</inf>C and 227.21 mAh/g for Mo<inf>2</inf>CO<inf>2</inf>. The open-circuit voltages (OCV) calculated from DFT total energies for the Na loadings retained after AIMD. The OVC is in the optimal range of 0–1.0 V, which helps prevent dendrite formation. The OCV values of 0.47 V for Mo<inf>2</inf>C and 0.65 V for Mo<inf>2</inf>CO<inf>2</inf>highlight their suitability as anodes. These results show that Mo<inf>2</inf>C and Mo<inf>2</inf>CO<inf>2</inf>have low energy barriers, high structural stability, and low OCV values, making them promising candidates for Na-ion battery anodes with properties that can be adjusted through biaxial strain modifications.
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Strong electron–phonon coupling and predicted high superconducting transition temperature of MXenes revealed in 2H-Mo2N under biaxial stress
(2024-12-15)
Kotmool, Komsilp
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Tsuppayakorn-aek, Prutthipong
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Bovornratanaraks, Thiti
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Kaewmaraya, Thanayut
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Sakdanuphab, Rachsak
Extensive investigations have been conducted on Mo-based MXenes due to their high superconducting temperatures (T<inf>c</inf>). This work theoretically reports strong electron–phonon coupling (EPC) and high T<inf>c</inf> (≈38 K) of 2H-Mo<inf>2</inf>N under biaxial stress, with excellent mechanical properties. EPC and T<inf>c</inf> are elucidated upon dynamically stable strain range. At 0% strain, EPC constant (λ) and T<inf>c</inf> are 1.32 and 22.7 K, respectively. They are improved when subjected to biaxial stresses. Strong EPC with λ over 2.0 occurs at −4%, −2.5%, and 5% strains, yielding enhanced T<inf>c</inf>. The finding suggests that the energy levels of electronic bands at the Fermi level are enhanced by strain, which enhances EPC. Moreover, the impact of functional groups on superconductivity has been investigated. The λ’s of Mo<inf>2</inf>NH<inf>2</inf> and Mo<inf>2</inf>NO<inf>2</inf> are reduced, and T<inf>c</inf> drops nearly to 20.0 and 0.9 K, respectively. This work provides an example of designing 2D superconductors by tuning atomic recipes and strain-dependent engineering.
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Stability, thermodynamic, electronic, and thermoelectric properties of triclinic Cu2Se structure
(2024-06-01)
Kotmool, Komsilp
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Khammuang, Satchakorn
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Rudradawong, Chalermpol
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Thatsami, Niphat
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Kaewmaraya, Thanayut
The conversion of heat into electricity using the thermoelectric effect is a crucial issue to tackle the ever-increasing global energy consumption. Cu<inf>2</inf>Se is one of the high-performance thermoelectric materials due to its liquid-like atomic structure, which minimizes the phonon-derived thermal conductivity. Nevertheless, the unambiguous atomic structure of the low-temperature phase, α-Cu<inf>2</inf>Se, remains controversial. By employing a combination of theoretical approaches including an evolutionary algorithm for structural searching, density functional theory, and lattice dynamics, the α-Cu<inf>2</inf>Se phase is proposed to crystalize in the dynamically stable triclinic Cu<inf>2</inf>Se structure (s.g. P1) which can be regarded as a monoclinic polymorph (s.g. P2<inf>1</inf>/c†) through slight distortion. The corresponding heat capacity (C<inf>V</inf>) and Debye temperature (Θ<inf>D</inf>) are 0.37 J/g K and 276 K, respectively, indicating low thermal conductivity in the material. The semiconducting P1 phase possesses an indirect gap of 1.0 eV. Additionally, based on the Boltzmann transportation theory, fundamental thermoelectric parameters around the transition temperature (300–500 K) are investigated. Beyond the semiconducting phase, a novel metallic phase identified as the triclinic P1̄ phase is also discovered, exhibiting a two-dimensional (2D) crystal geometry.
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First-principles study on structural stabilities, mechanical properties, and biaxial strain-induced superconductivity in Janus MoWC monolayer
(2024-05-27)
Thasitha, Sirinee
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Tsuppayakorn-Aek, Prutthipong
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Udomkijmongkol, Anan
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Khammuang, Satchakorn
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Kaewmaraya, Thanayut
The unique attributes of hydrophilicity, expansive surface groups, remarkable flexibility, and superior conductivity converge in MXene, a pioneering 2D material. Owing to MXene's exceptional properties, diverse strategies have been explored to enhance its characteristics. Janus MXene and stress-strain response considerations represent the primary avenues of interest today. In this study, we investigated the Janus MXene structure under biaxial stress using first-principles calculations. The most stable configuration of Janus MoWC MXene identified in our analysis exhibits an atomic arrangement known as the hexagonal (2H) phase. Subsequently, we examined the mechanical and electronic properties of 2H-MoWC when subjected to biaxial strain. Our findings indicate that the 2H phase of Janus MoWC MXene demonstrates superior strength compared to the tetragonal (1T) phase. Analysis of the ELF of the 2H-MoWC structure unveiled that the robust C-C bond within the material is the underlying factor enabling the 2H phase to withstand a maximum of 9% tensile strain. Furthermore, we demonstrate that 2H-MoWC is a superconductor with the superconducting temperature (T<inf>c</inf>) of 1.6 K, and the superconductivity of 2H phase can be enhanced by biaxial strain with the T<inf>c</inf> reaching 7 K. This study offers comprehensive insights into the properties of Janus MoWC monolayer under biaxial stress, positioning it as a promising candidate for 2D straintronic applications.
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First-principles study of 2H-Mo2C-based MXenes under biaxial strain as Li-battery anodes
(2023-06-27)
Khammuang, Satchakorn
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Pratumma, Anucha
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Sakulkalavek, Aparporn
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Kaewmaraya, Thanayut
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Hussain, Tanveer
MXenes, a family of superior 2D materials, have been intensively investigated because they have many promising properties, particularly high-performance energy storage and high flexibility. To approach the expected critical benchmarks of such materials, the strain dependence of the atomic structure is widely considered for tuning the related properties. In this work, by means of density functional theory, we demonstrate the potential application of the strained 2H phase of Mo<inf>2</inf>C-based MXenes (Mo<inf>2</inf>C and Mo<inf>2</inf>CO<inf>2</inf>) as anode materials for lithium-ion batteries (LIBs). Adsorption and diffusion of Li on the surfaces of both materials and the impact of biaxial strain (ϵ<inf>b</inf>) in the range of −4% to 4% are insightfully investigated. The lowest adsorption energy of Mo<inf>2</inf>C is −0.96 eV, and that of Mo<inf>2</inf>CO<inf>2</inf> is −3.13 eV at ϵ<inf>b</inf> = 0%. The diffusion of Li ions, considering the pathway between the first two most favorable adsorption sites, reveals that the biaxial strain refinement under compressive strain decreases the energy barrier, but the induction of tensile strain increases it in both MXenes. The ranges of the energy barriers of Li-ion adsorption on the surfaces of Mo<inf>2</inf>C and Mo<inf>2</inf>CO<inf>2</inf> are 31-57 meV and 177-229 meV, respectively. Interestingly, the storage capacity of Li can reach three layers corresponding to a comparably high theoretical capacity of 788.61 mA h g−1 for Mo<inf>2</inf>C and 681.64 mA h g−1 for Mo<inf>2</inf>CO<inf>2</inf>. The atomic configurations are stable, as verified by the negative adsorption energy as well as the slightly distorted structures, by using ab initio molecular dynamics (AIMD) simulations at 400 K. Moreover, average open circuit voltages (OCVs) of 0.35 V and 0.63 V (at ϵ<inf>b</inf> = 0%) are reported for Mo<inf>2</inf>C and Mo<inf>2</inf>CO<inf>2</inf>, respectively. Furthermore, the tensile strain results in an increase in the OCVs, while compression has the opposite effect. These computational results provide some basic information on the behaviors of Li-ion adsorption and diffusion on Mo<inf>2</inf>C-based MXenes upon tuning biaxial strain. They also give a guideline on what conditions are appropriate for practically implementing these MXenes as electrode materials in LIBs.
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Biaxial stress and functional groups (T = O, F, and Cl) tuning the structural, mechanical, and electronic properties of monolayer molybdenum carbide
(2022-07-19)
Kotmool, Komsilp
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Kaewmaraya, Thanayut
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Hussain, Tanveer
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Ahuja, Rajeev
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Luo, Wei
MXenes are a family of novel two-dimensional (2D) materials attracting intensive interest because of the rich chemistry rooted from the highly diversified surface functional groups. This enables the chemical optimization suitable for versatile applications, including energy conversion and storage, sensors, and catalysis. This work reports the ab initio study of the crystal energetics, electronic properties, and mechanical properties, and the impacts of strain on the electronic properties of tetragonal (1T) and hexagonal (2H) phases of Mo<inf>2</inf>C as well as the surface-terminated Mo<inf>2</inf>CT<inf>2</inf> (T = O, F, and Cl). Our findings indicate that 2H-Mo<inf>2</inf>C is energetically more stabilized than the 1T counterpart, and the 1T-to-2H transition requires a substantial energy of 210 meV per atom. The presence of surface termination T atoms on Mo<inf>2</inf>C intrinsically induces variations in the atomic structure. The calculated structures were selected based on the energetic and thermodynamic stabilities (400 K). The O atom prefers to be terminated on 2H-Mo<inf>2</inf>C, whereas the Cl atom energetically stabilizes on 1T-Mo<inf>2</inf>C. Meanwhile, with certain configurations, 2H-Mo<inf>2</inf>CF<inf>2</inf> and 1T-Mo<inf>2</inf>CF<inf>2</inf> with slightly different energies could exist simultaneously. The Mo<inf>2</inf>CO<inf>2</inf> possesses the highest mechanical strength and elastic modulus (σ<inf>max</inf> = 52 GPa at ϵ<inf>b</inf> = 20% and E = 507 GPa). The nature of the ordered centrosymmetric layer and the strong bonding between 4 d-Mo and 2 p-O of 2H-Mo<inf>2</inf>CO<inf>2</inf> are responsible for its promising mechanical properties. Interestingly, the topological properties of 2H-Mo<inf>2</inf>CO<inf>2</inf> at a wide range of strains (−10% to 12%) are reported. Moreover, 2H-Mo<inf>2</inf>CF<inf>2</inf> is metallic through the range of calculation. Meanwhile, originally semiconducting 1T-Mo<inf>2</inf>CF<inf>2</inf> and 1T-Mo<inf>2</inf>CCl<inf>2</inf> preserve their features under the ranges of the strain of −2% to 10% and −1% to 5%, respectively, beyond which they undergo the semiconductor-to-metal transitions. These findings would guide the potential applications in modern 2D straintronic devices.
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Structural Phase Transitions, Electronic Properties, and Hardness of RuB4under High Pressure in Comparison with FeB4and OsB4
(2020-07-09)
Kotmool, Komsilp
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Tsuppayakorn-Aek, Prutthipong
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Kaewmaraya, Thanayut
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Pinsook, Udomsilp
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Ahuja, Rajeev
We have employed an evolutionary algorithm with first-principles calculations to investigate the pressure-induced structural evolution of RuB4 up to 500 GPa. The ambient phase is predicted to be a hexagonal structure (P63/mmc). The novel phases consisting of monoclinic (C2/c) and orthorhombic (Immm) structures are proposed to be the high-pressure phases at the pressure intervals of 198-388 GPa and beyond 388 GPa, respectively. The stability of the predicted phases is confirmed by both dynamic and elastic calculations. The electronic and mechanical properties of the predicted phases are evaluated and mainly discussed compared to the isoelectronic metal tetraborides, i.e., FeB4 and OsB4. In contrast to FeB4 and OsB4, all the stable phases of RuB4 are metal or semimetal, and any semiconducting phases do not emerge in the transformation pathway of RuB4. The nature of chemical bonding investigated by ELF, MPA, and pCOHP calculations reveals that the atomic configurations and the degree of covalent bonding of the predicted phases are responsible for lower hardness compared to those of FeB4 and OsB4. The results of this work provide more understanding of the family of metal tetraboride for designing metal-boride-based hard/superhard materials.

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