arXiv subjects

Julio R. Sambrano

Publications and source records attributed to Julio R. Sambrano.

At least 19 recordsLinked to original sources

arXiv2026

Phase-Dependent Excitonic Light Harvesting and Photovoltaic Limits in Monolayer Y2TeO2 MOenes

We investigate phase-dependent electronic and excitonic phenomena in monolayer Y2TeO2 MOenes in the 1T and 2H polymorphs using first-principles theory and an effective many-body framework. Phonon spectra and elastic stability criteria establish both phases as dynamically and mechanically stable. Quasiparticle band structures reveal direct gaps in the near-infrared to visible range, with gap values increasing systematically from semilocal to hybrid exchange treatments. Optical spectra computed using a tight-binding Bethe-Salpeter approach demonstrate pronounced excitonic resonances arising from reduced dimensionality and weak dielectric screening. The exciton binding energies reach 152 meV in the 1T phase and 126 meV in the 2H phase, reflecting enhanced quantum confinement in the structurally denser phase. Our results identify Y2TeO2monolayers as a rare class of stable, direct-gap MOenes with strong excitonic effects, providing a platform for exploring many-body physics in low-dimensional oxychalcogenide systems especially for photovoltaic applications.

physics.comp-ph↗

arXiv2026

Exploring the Potential of Two-dimensional Borospherene for Toxic Gas Sensing and Capture: A DFT Study

Two-dimensional (2D) boron-based materials have gained increasing interest due to their exceptional physicochemical properties and potential technological applications. In this way, borospherenes, a 2D Boron-based fullerene-like lattice (2D-B40), are explored due to their potential for capturing and detecting toxic gases, such as CO, NO, NH3, and SO2. Therefore, density functional theory simulations were carried out to explore the adsorption energy and the distinct interaction regimes, where CO exhibits weak physisorption (-0.16 eV), while NO (-2.24 eV), NH3 (-1.47 eV), and SO2 (-1.51 eV) undergo strong chemisorption. Bader charge analysis reveals significant electron donation from 2D-B40 to NO and electron acceptance from SO2. These interactions cause measurable shifts in work function, with SO2 producing the most significant modulation (14.6%). Remarkably, ab initio molecular dynamics simulations (AIMD) reveal spontaneous SO2 decomposition at room temperature, indicating dual functionality for both sensing and environmental remediation. Compared to other boron-based materials, such as chi3-borophene, beta12-borophene, and B40 fullerene, 2D-B40 exhibits superior gas affinity, positioning it as a versatile platform for the detection and capture of toxic gases.

cond-mat.mtrl-sci↗

arXiv2026

Goldene monolayer as a highly effective catalyst for polysulfide anchoring and conversion: A theoretical study

We use first-principles density functional theory to investigate how lithium sulfide and polysulfide clusters (Li2S, Li2S2, Li2S4, Li2S6, Li2S8, and S8) bind to Goldene, a new two-dimensional gold allotrope. All Li-S species exhibit robust binding to Goldene. The adsorption energies range from -4.29 to -1.90 eV. S8 that is alone interacts much less strongly. Charge density difference and Bader analyses indicate that substantial charge is transferred to the substrate, with a maximum 0.92 e for Li-rich clusters. This transfer induces polarization at the interface and shifts the work function to 5.30-5.52 eV. Projected density-of-states calculations indicate that Au-d and S-p states strongly mix near the Fermi level. This hybridization indicates that the electronic coupling is strong. Based on these results, the reaction free-energy profile for the stepwise conversion of S8 to Li2S on Goldene is thermodynamically favorable. The overall stabilization is -3.64 eV, and the rate-determining barrier for the Li2S2 -> Li2S step is 0.47 eV. This shows that Goldene is an effective surface for anchoring and mediating lithium polysulfide reactions.

cond-mat.mtrl-sci↗

arXiv2025

A Three-Dimensional Dodecaphenylyne-Derived Carbon Allotrope with Anisotropic and Auxetic-Like Mechanical Behavior

We introduce 3D-DPhyne, a novel three-dimensional (3D) carbon allotrope derived from the dodecaphenylyne framework, and investigate its structural, electronic, optical, and mechanical properties using first-principles calculations. The proposed structure forms a tetragonal, topologically complex network of four-, six-, and twelve-membered carbon rings with mixed sp/sp^2 hybridization and a formation energy of -7.87 eV/atom, comparable to other stable carbon allotropes. Phonon dispersion calculations show no imaginary modes, and ab initio molecular dynamics simulations at 1000~K confirm robust thermal stability without bond breaking. Electronic structure analysis reveals metallic character, with multiple bands crossing the Fermi level and dominant contributions from carbon p orbitals, consistent with a fully delocalized 3D $\pi$-conjugated network. The optical response is anisotropic, exhibiting strong absorption in the visible and ultraviolet regions and low reflectivity across a broad range of photon energies. Mechanical analysis reveals pronounced elastic anisotropy, with Young's modulus varying from approximately 40 to 490 GPa depending on direction. Poisson's ratio displays unconventional directional behavior, including auxetic-like responses.

cond-mat.mtrl-sci↗

arXiv2025

Quadrene: A Novel Quasi-2D Carbon Allotrope with High Carrier Mobility

We present a comprehensive first-principles investigation of a novel carbon allotrope characterized by quasi-tetragonal atomic motifs and quasi-two-dimensional structural behavior. Structural analysis reveals an open framework composed of alternating diamond-like and square units, while thermodynamic assessments indicate a negative formation energy, suggesting high intrinsic stability. Phonon spectra confirm dynamical robustness, and \textit{ab initio} molecular dynamics simulations at 1000~K validate its thermal resilience. Furthermore, the system exhibits an indirect bandgap of 1.58 eV at the HSE06 level, anisotropic mechanical behavior, and a broadband optical response, reinforcing its potential for nanoelectronic and optoelectronic applications. The highly anisotropic mechanical behavior is characterized by an in-plane Young's modulus ranging from 80 to 550 GPa, depending on crystallographic direction. Additionally, the electronic transport properties exhibit pronounced anisotropy, with hole mobilities reaching up to 5.83 x 10^6 cm^2/V . s and electron mobilities up to 6.40 x 10^6 cm^2/V . s along different crystallographic directions, highlighting the material's potential for directionally selective nanoelectronic device applications.

cond-mat.mtrl-sci↗

arXiv2025

Sodium-Decorated Ennea-Graphene: A Novel 2D Carbon Allotrope for High-Capacity Hydrogen Storage

The development of safe, efficient, and reversible hydrogen storage materials is critical for advancing hydrogen-based energy technologies and achieving carbon-neutral goals. Ennea-Graphene, a new 2D carbon allotrope made of 4-, 5-, 6-, and mainly 9-membered carbon rings (nonagons), is introduced via Density Functional Theory (DFT) calculations. Phonon dispersion and ab initio molecular dynamics demonstrate that the monolayer is mechanically and dynamically stable at 300 K, as no imaginary modes are detected. The pristine system further exhibits metallic-like electronic behavior. The material exhibits high in-plane stiffness (Young modulus of 255 N/m). Sodium adsorption at the centers of the nonagonal rings is energetically favorable, with a binding energy of approximately -1.56 eV, leading to the formation of the Na@Ennea-Graphene complex. The calculated H2 adsorption energies range from -0.15 eV to -0.18 eV. The Na-decorated structure demonstrates excellent hydrogen storage performance, reversibly adsorbing up to four H2 molecules per Na atom (8.8 wt\% H2). This capacity surpasses the U.S. Department of Energy's 2025 target for onboard hydrogen storage materials. The adsorbed H2 remains molecular (H-H bond of 0.76~\AA) and can be released under near-ambient conditions, as verified by 300 K ab initio molecular dynamics simulations. These findings position sodium-decorated Ennea-Graphene as a promising nanomaterial for next-generation hydrogen storage technologies.

physics.app-ph↗

arXiv2025

Alpha-, Beta-, and Gamma-TODD-G: Novel 2D Planar Carbon Allotropes

We present a comprehensive first-principles investigation of three novel two-dimensional carbon allotropes: alpha-, beta-, and gamma-TODD-Graphene (TODD-G), composed of 3-8-12-16, 3-8-12-16, and 3-4-8-12 interconnected carbon rings with sp/sp2 hybridization, respectively. Structural optimization, phonon spectra, and ab initio molecular dynamics simulations confirm their thermal and dynamical stability. All phases exhibit metallic electronic behavior, with distinct Dirac-like features and tilted Dirac cones that suggest anisotropic charge transport. Mechanical analysis reveals tunable anisotropy: alpha-TODD-G is strongly anisotropic, beta-TODD-G shows moderate anisotropy, and gamma-TODD-G displays an almost isotropic mechanical response. Optical spectra further differentiate the phases, with gamma-TODD-G showing strong absorption in the infrared region, while alpha- and beta-TODD-G mainly absorb in the visible and ultraviolet ranges.

cond-mat.mtrl-sci↗

arXiv2025

$\beta$-Irida-Graphene: A New 2D Carbon Allotrope for Sodium-Ion Battery Anodes

The quest for sustainable and efficient energy storage has driven the exploration of sodium-ion batteries (SIBs) as promising alternatives to lithium-ion systems. However, the larger ionic radius of sodium poses intrinsic challenges such as slow diffusion and structural strain in conventional electrode materials. As a contribution to addressing these limitations, the \b{eta}-Irida-graphene ($\beta$-IG) is herein introduced, a novel two-dimensional (2D) carbon allotrope derived from Irida-graphene, featuring a diverse polygonal lattice of 3-, 4-, 6-, 8-, and 9-membered carbon rings. Through density functional theory and ab initio molecular dynamics simulations, $\beta$-IG demonstrated remarkable thermal, dynamical, and mechanical stability, coupled with intrinsic conductive character and efficient sodium-ion mobility (energy barriers < 0.30 eV). Furthermore, the adsorption of sodium ions was energetically favorable, delivering an impressive predicted specific capacity of 554.5 mAh/g. The reported findings highlight $\beta$-IG as a good potential anode candidate for next-generation SIBs, offering high-rate performance and structural robustness, and expanding the functional design space for advanced carbon-based electrode materials.

cond-mat.mtrl-sci↗

arXiv2025

Propylenidene: A Novel Metallic Carbon Monolayer with Unconventional Ring Topology

Two-dimensional (2D) carbon allotropes have drawn significant interest owing to their impressive physical and chemical characteristics. Following graphene's isolation, a wide range of 2D carbon materials has been suggested, each with distinct electronic, mechanical, and optical traits. Rational design and synthesis of new 2D carbon structures hinge on experimentally reported precursors. Here, we present a 2D carbon allotrope, propylenidene (PPD), originating from bicyclopropylidene. PPD forms a rectangular lattice with 3, 8, and 10-membered carbon rings. Density functional theory (DFT) simulations investigate its structural, electronic, mechanical, and optical properties. Our study shows PPD to be metallic. PPD exhibits absorption in the infrared and visible range, showing directional dependence in its response. Mechanically, PPD exhibits marked anisotropy; Young's modulus ($Y$) varies between 205.83 N/m and 164.46 N/m. These findings underscore the potential of this novel monolayer in applications such as energy storage, gas sensing, and optoelectronics.

cond-mat.mtrl-sci↗

arXiv2025

OLi3-decorated Irida-graphene for High-capacity Hydrogen Storage: A First-principles Study

Efficient hydrogen storage in solid-state materials is essential for next-generation energy systems, yet achieving a high gravimetric capacity with optimal adsorption characteristics remains a critical challenge. Although Li-decorated irida-graphene (IG) has shown promising hydrogen storage potential, its capacity is limited to $\sim$ 7wt\%, which, despite exceeding the U.S. DOE target, remains inadequate for large-scale applications. Additionally, Li clustering over extended cycles may compromise adsorption efficiency and structural stability. In this study, we employ first-principles calculations to investigate the hydrogen storage potential of IG decorated with superalkali OLi$_3$ clusters, aiming to enhance the adsorption capacity and stability for advanced hydrogen storage technologies. Our findings show that the OLi$_3$ clusters exhibit a significant binding energy of -3.24 eV, which highlights its strong interaction with the IG. OLi$_3$@IG complex can host up to 12H$_2$ molecules, with optimal maximum storage capacity of 10.00 wt\%. Additionally, the release temperature (T$_R$) and \textit{ab initio} molecular dynamics (AIMD) simulations indicate that H$_2$ molecules can be efficiently released at operating temperatures under ambient conditions. These results highlight the potential of OLi$_3$-decorated irida-graphene as a promising candidate for reversible hydrogen storage.

cond-mat.mtrl-sci↗

arXiv2025

Sodium-Decorated P-C3N: A Porous 2D Framework for High-Capacity and Reversible Hydrogen Storage

The development of reversible hydrogen storage materials has become crucial for enabling carbon-neutral energy systems. Based on this, the present work investigates the hydrogen storage on the sodium-decorated P-C$_3$N (Na@P-C$_3$N), a porous carbon nitride monolayer recently proposed as a stable semiconductor. First-principles calculations reveal that Na atoms preferentially adsorb with an adsorption energy of -4.48~eV, effectively suppressing clusterization effects. Upon decoration, the system becomes metallic, while \textit{ab initio} molecular dynamics simulations confirm the thermal stability of Na@P-C$_3$N at 300~K. Hydrogen adsorption on Na@P-C$_3$N occurs through weak physisorption, with energies ranging from -0.18 to -0.28~eV, and desorption temperatures between 231 and 357~K. The system can stably absorb 16 H$_2$ molecules per unit cell, corresponding to a gravimetric storage capacity of 9.88~wt\%, surpassing the U.S. Department of Energy target. These results demonstrate that Na@P-C$_3$N is a promising candidate for lightweight, stable, and reversible hydrogen storage.

cond-mat.mtrl-sci↗

arXiv2025

First-Principles and Machine Learning Investigation of the Structural and Optoelectronic Properties of Dodecaphenylyne: A Novel Carbon Allotrope

We report the computational discovery and characterization of Dodecaphenylyne (DP), a novel carbon allotrope with a distinctive geometric arrangement. DP structural, thermodynamic, mechanical, electronic, and optical properties were evaluated using density functional theory and a machine learning interatomic potential trained explicitly for this material. The formation energy of -7.98 eV/atom indicates high thermodynamic stability, further supported by the absence of imaginary phonon modes and the preservation of structural integrity up to 1000 K in ab initio molecular dynamics simulations. Mechanical analysis reveals high in-plane stiffness with directional dependence: Young's modulus values of 469.09 GPa and 600.41 GPa along the x and y directions, respectively. Electronic band structure and projected density of states analyses confirm the DP semiconducting character. Calculations of carrier mobility using the deformation potential theory reveal pronounced anisotropy, with maximum values reaching up to $30.6 \times 10^4$ cm$^2$/V$\cdot$s (electrons, e) and $8.4 \times 10^4$ cm$^2$/V$\cdot$s (holes, h), much higher than the observed for other 2D materials. DP also exhibits anisotropic optical absorption in the visible and ultraviolet spectrum, highlighting its potential for optoelectronic applications.

cond-mat.mtrl-sci↗

arXiv2025

Potassium Decoration on Graphenyldiene Monolayer for Advanced Reversible Hydrogen Storage

Potassium-decorated graphenyldiene (K@GPD) is investigated as a promising two-dimensional material for reversible hydrogen storage using first-principles density functional theory calculations. Potassium atoms bind strongly to the GPD monolayer, and ab initio molecular dynamics (AIMD) simulations confirm the thermal stability of the functionalized system at 300 K. Hydrogen adsorption energies range from -0.11 to -0.14 eV per H$_2$, denoting reversible storage. At full coverage (18 H$_2$ molecules), the system reaches a storage capacity of 8.82 wt\%, exceeding the U.S. DOE target. AIMD simulations reveal spontaneous H$_2$ desorption at ambient temperature, demonstrating excellent reversibility.

cond-mat.mtrl-sci↗

arXiv2025

TPHE-Graphene: A First-Principles Study of a New 2D Carbon Allotrope for Hydrogen Storage

The shift from fossil fuels to renewable energy sources is essential for reducing global carbon emissions and addressing climate change. Developing advanced materials for efficient hydrogen storage enables sustainable energy solutions in this context. Herein, we propose sodium-decorated TPHE-graphene as a high-performance two-dimensional material for hydrogen storage. Density functional theory (DFT) calculations demonstrate that TPHE-graphene exhibits dynamical, thermal, energetic, and mechanical stability, as confirmed by cohesive energy, phonon dispersion, and molecular dynamics simulations. The monolayer displays metallic behavior and a high Young's modulus of 250.46 N/m. Upon sodium decoration, strong chemisorption occurs with a binding energy of -2.08 eV and minimal tendency for Na atom clustering. Hydrogen adsorption analysis reveals that each Na atom can bind up to five H$_2$ molecules, resulting in a gravimetric storage capacity of 9.52 wt\%. The calculated H$_2$ adsorption energies range from -0.22 eV to -0.18 eV, falling within the ideal range for reversible adsorption under ambient conditions. These findings highlight Na-decorated TPHE-graphene as a structurally robust and efficient hydrogen storage material well-suited for future green energy applications.

cond-mat.mtrl-sci↗

arXiv2025

HOP-graphene: A high-capacity anode for Li/Na-ion batteries unveiled by first-principles calculations

The growing demand for efficient energy storage has driven the search for advanced anode materials for lithium- and sodium-ion batteries (LIBs and SIBs). In this context, we report the application of HOP-graphene (a 5-6-8-membered 2D carbon framework) as a high-performance anode material for LIBs and SIBs using density functional theory simulations. Diffusion studies reveal low energy barriers of 0.70 eV for Li and 0.39 eV for Na, indicating superior mobility at room temperature compared to other carbon allotropes, like graphite. Full lithiation and sodiation accommodate 24 Li and 22 Na atoms, respectively, delivering outstanding theoretical capacities of 1338 mAh/g (Li) and 1227 mAh/g (Na). Bader charge analysis and charge density difference maps confirm substantial electron transfer from the alkali metals to the substrate. Average open-circuit voltages of 0.42 V (Li) and 0.33 V (Na) suggest favorable electrochemical performance. HOP-graphene also demonstrates excellent mechanical strength. These findings position HOP-graphene as a promising candidate for next-generation LIB and SIB anodes.

cond-mat.mtrl-sci↗

arXiv2025

Athos-Graphene: Computational Discovery of an Art-Inspired 2D Carbon Anode for Lithium-Ion Batteries

Two-dimensional (2D) carbon allotropes have attracted growing interest for their structural versatility and potential in energy storage and nanoelectronics. We propose Athos-Graphene (AG), a novel 2D carbon allotrope inspired by the geometric patterns of Brazilian artist Athos Bulc\~ao. Designed using density functional theory, AG features a periodic structure with high thermodynamic and thermal stability, as evidenced by a low cohesive energy of -7.96 eV/atom, the absence of imaginary phonon modes, and robust performance in ab initio molecular dynamics simulations up to 1000 K. It exhibits anisotropic mechanical properties, with Young's modulus values of 585 GPa and 600 GPa along the x- and y-directions, and Poisson's ratios of 0.19 and 0.17, respectively. Electronic structure analyses confirm its metallic behavior, while optical studies reveal anisotropic absorption in the visible and UV regions. For lithium-ion storage, Athos-Graphene shows strong Li adsorption (-2.3 to -1.0 eV), a high theoretical capacity of 836.78 mAh/g, and a low average open-circuit voltage of 0.54 V. Lithium diffusion barriers are as low as 0.3 eV on the surface and 0.66 eV between layers, with a high diffusion coefficient greater than 6x10^-6 cm^2/s. These features highlight AG as a promising anode material for high-performance lithium-ion batteries.

cond-mat.mtrl-sci↗

arXiv2025

A Novel Graphyne-Like Carbon Allotrope: 2D Dewar-Anthracyne

Anthracyne (2DDA). 2DDA consists of chains of Dewar-anthracenes connected by acetylenic linkages. DFT-based simulations show that 2DDA is thermally stable and exhibits no imaginary phonon modes, confirming its dynamic stability. 2DDA is metallic with Dirac-like features near the Fermi level, dominated by C pz orbitals. It shows marked mechanical anisotropy, with Young's modulus of 176.24 N/m (x) and 31.51 N/m (y), shear modulus up to 69.14 N/m, and Poisson's ratio varying from 0.27 to 0.87. The material also exhibits strong anisotropic optical absorption in the visible and ultraviolet ranges. Raman and IR spectra reveal intense bands at 648 cm-1 (Raman) and 1292 cm-1 (Infrared). Nanoribbon structures derived from 2DDA exhibit diverse electronic behaviors, from metals up to bandgap values of up to 0.42 eV, depending on the edge-type terminations and width. These findings demonstrate the 2DDA potential for nanoelectronic and optoelectronic applications.

cond-mat.mtrl-sci↗

arXiv2025

Anthraphenylenes: Porous 2D Carbon Monolayers with Biphenyl-Anthracene Frameworks and Type-II Dirac line nodes

Carbon's versatility allows it to form diverse structures with unique properties, driven by its moderate electronegativity, small ionic radius, and ability to adopt \textit{sp}, \textit{sp\textsuperscript{2}}, and \textit{sp\textsuperscript{3}} hybridizations, individually or in combination. In this work, we introduce three novel 2D carbon allotropes -- $\alpha$, $\beta$, and $\gamma$-anthraphenylenes -- derived from biphenylene and Dewar-anthracene motifs, investigated through density functional theory calculations. Their thermodynamic and dynamic stability are confirmed by cohesive energy ($-7.02$ to $-7.26$ eV/atom), phonon dispersion, and \textit{ab initio} molecular dynamics simulations. The electronic structure analysis shows that all three anthraphenylenes display metallic behavior. All anthraphenylenes feature type-II Dirac Line Nodes (DLNs). Mechanical analysis highlights significant anisotropy, mainly in $\gamma$-anthraphenylene, which exhibits the highest rigidity. These monolayers feature a porous architecture with tunable mechanical properties, making them promising candidates for nanoelectronics and energy storage applications. By expanding the family of 2D carbon materials, anthraphenylenes provide new avenues for functional nanomaterial design.

cond-mat.mtrl-sci↗