arXiv subjects

Brahmananda Chakraborty

Publications and source records attributed to Brahmananda Chakraborty.

At least 19 recordsLinked to original sources

arXiv2026

Hydrogen Storage on Transition-Metal-Decorated Nitrogen-Modified Carbon Nanoribbons

Recently synthesized carbon nanoribbons (CNRs) were investigated for hydrogen (H2) storage using first-principles density functional theory calculations. Pristine CNRs exhibited weak H2 adsorption; therefore, the host structure was modified by substituting carbon atoms at the C-H edges with 12 nitrogen atoms, followed by Mn and Y doping to enhance H2 binding. A maximum of five metal atoms could be accommodated on the 12N-CNRs. Electronic structure analysis revealed strong orbital hybridization between the metal atoms and the CNRs, while binding energy calculations confirmed the structural stability of the doped systems. Bader charge analysis further quantified the charge transfer between the metal atoms and the host structure. The average H2 adsorption energies were calculated to be -0.40 eV/H2 for the Mn-doped system and -0.25 eV/H2 for the Y-doped system, which are within the desirable range for reversible hydrogen storage. The maximum theoretical gravimetric storage capacities at 0 K reached 7.48 wt% for the Mn-doped system and 6.55 wt% for the Y-doped system. Under practical conditions of 30 atm and 298.15 K, the storage capacity of the Y-doped system decreased to 6.04 wt%, whereas the Mn-doped system maintained its full capacity of 7.48 wt%. Thermodynamic analysis indicated that H2 adsorption is favored at low temperatures and high pressures, while desorption becomes feasible at elevated temperatures and lower pressures. These results demonstrate that Mn- and Y-doped CNRs satisfy key U.S. Department of Energy requirements for reversible H2 storage and show promise as potential hydrogen storage materials under near-ambient conditions.

cond-mat.mtrl-sci↗

arXiv2026

Anomalous behavior of native point defects in C2-ordered antiferromagnet $α$-MnO$_2$

$α$-MnO$_2$ is an emerging material for electronic, optoelectronic, and energy applications, owing to its structural flexibility and defect-driven functionality. During synthesis of $α$-MnO$_2$, native oxygen vacancies readily form and are typically compensated by foreign dopants. A thorough understanding of intrinsic defects is therefore essential for enabling controlled extrinsic doping and optimizing material performance. Using density functional approach, we investigate the structural, electronic, magnetic, and optical properties of the ground state C2-type antiferromagnetic $α$-MnO$_2$ in the presence of native point defects, including interstitials, vacancies, and antisites. We compute their thermodynamic stability, incorporating electrostatic corrections to eliminate spurious long-range interactions. Mn interstitial (Mn$_\text{i}$) and Mn antisite O (Mn$_\text{O}$) introduce shallow donor levels, whereas O-vacancy (V$_\text{O}$) exhibit amphoteric behavior and act as compensating centers. The calculated defect formation energies reveal pronounced competition between donor- and acceptor-type native defects, leading to strong intrinsic defect compensation under both Mn-rich and O-rich growth conditions. Mn vacancy (V$_\text{Mn}$) remains ionized across the band gap and behaves as a shallow acceptor, suggesting its potential role under suitable non-equilibrium growth conditions, whereas O antisite Mn (O$_\text{Mn}$) forms deep acceptor levels. BSE@G$_0$$W_0$ calculations reveal a strongly anisotropic optical response in stoichiometric $α$-MnO$_2$, while native point defects introduce pronounced sub-gap excitations and enhanced dielectric screening, with vacancies producing the largest effect.

cond-mat.mtrl-sci↗

arXiv2026

First-Principles Investigation of 2D Copper Boride as a High-Performance Anode for Lithium-Ion Batteries

In this study, we investigate the two-dimensional copper boride, Cu$_8$B$_{14}$, as a possible anode material for lithium-ion batteries using first-principles calculations. We found that the structural integrity of the monolayer was preserved even at elevated temperatures, while electronic calculations confirm the metallic character of the pristine and Li-loaded systems. On systematic lithiation on Cu$_8$B$_{14}$ a specific capacity of 430mAhg$^{-1}$ was obtained. A Li diffusion barrier of 0.32eV for the most favourable path, along with a diffusivity of approximately $2.26 \times 10^{-5}$cm$^2$s$^{-1}$ was obtained. The open-circuit voltage of 0.53 V falls within the optimal anode range of 0.1--1.0 V. These combined characteristics point to Cu$_8$B$_{14}$ as a compelling candidate for advanced battery anodes. Furthermore, to understand the defect and its effect on different parameters, we investigated an experimentally identified line-defect configuration of copper boride. The line defect monolayer retains a theoretical capacity of about 385mAhg$^{-1}$, while the introduced line defect further reduces the Li migration barrier to 0.21eV, yielding an enhanced macroscopic diffusivity of $\sim$5.6$\times$10$^{-4}$cm$^{2}$s$^{-1}$ and confirming that structural defects accelerate Li-ion transport kinetics in this material.

cond-mat.mtrl-sci↗

arXiv2026

Pressure-driven vibrational and structural peculiarities in the honeycomb layered magnetoelectrics Mn4(B)2O9 (B= Nb, Ta)

The high-pressure behavior of two Mn-based honeycomb-structured magnetoelectric materials, Mn4Nb2O9 (MNO) and Mn4Ta2O9 (MTO), was investigated using Raman spectroscopy, synchrotron x-ray diffraction, and density functional theory (DFT) calculations. In MTO, the application of a small pressure of only 0.5 GPa induces an isostructural transition driven by local symmetry breaking. With further increase in pressure, three additional isostructural transitions are observed at about 3.2, 6, and 10 GPa, followed by the onset of a long-range structural transition near 14 GPa, where the ambient P-3c1 phase begins to transform into a P2/c phase. These two phases coexist up to 27 GPa. The Nb analogue, MNO, also exhibits similar isostructural transitions at about 2, 6.6, and 10 GPa. However, the onset of the mixed P2/c and P-3c1 phases occurs at a slightly lower pressure of 12.5 GPa, with phase coexistence extending up to 26.5 GPa. These long-range transitions are supported by pressure-dependent enthalpy changes obtained from DFT calculations. Rietveld refinement reveals pronounced anisotropic lattice compression, with a 42 to 49 percent difference between the c and a axes, leading to a notable reduction in the c/a ratio. This anisotropy may strengthen interlayer coupling and promote magnetic ordering under compression, consistent with the appearance of Raman modes similar to those reported at low temperatures, together with anomalous changes in Raman mode linewidth and intensity. The marked changes in Raman self-energy parameters, anomalies in the reduced pressure-Eulerian strain profile, and the onset of local symmetry breaking at much lower pressures in MTO than in MNO highlight the important role of differences in spin-orbit coupling strength and orbital hybridization associated with Nb5+ and Ta5+ cations.

cond-mat.mtrl-sci↗

arXiv2025

First Principles study of Photocatalytic Water Splitting in BO Monolayer: Effect of Strain and Surface Functionalization

Light element based two dimensional (2D) materials are promising photocatalysts for hydrogen production via water splitting. Boron oxide (BO) is a recently synthesized 2D monolayer which has yet to be thoroughly explored for its potential applications. In this article, using first principles calculations, we report, for the first time, the visible-light photocatalytic activity of a BO monolayer for water splitting under mechanical strain and surface modification with single- and double-atom decorations (C, N, Si, Ge, P, As). The pristine BO monolayer exhibits an indirect band gap of 3.8 eV with band edges spanning the water redox potentials, but its optical absorption lies in the UV region (~ 4.5 eV). Strain engineering tunes the band gap and band alignment with a minimal shifting in the optical absorption (~0.5 eV). Single atom decoration produces a metallic state for elements like N, P, As, and an insulating state for single C, Si, Ge with a partial shifting in optical absorption. In contrast, double atom decoration produces substantial band gap reduction, improved band alignment, a pronounced red-shift in optical absorption into the visible range (1.6 to 3.2 eV) thus satisfying the criteria for water splitting. The stability of all the adsorbed configurations was confirmed by negative formation energy and ab-initio molecular dynamics simulations. These findings suggest BO monolayer functionalization can improve photocatalytic efficiency, providing hydrogen generation insights.

cond-mat.mtrl-sci↗

arXiv2025

Unraveling the Surface Stability and Chemical Reactivity of Aza-Triphenylene Monolayer under O$_2$ and H$_2$O Exposure

Environmental oxidation has a great impact in tuning the physical, chemical and electronic properties of two-dimensional (2D) monolayers which can affect their practical applications in nanoscale engineering devices under ambient conditions. aza-triphenylene is a recently synthesized 2D materials whose practcal applications have not been systematically studied yet. In this study, we report for the first time, the adsorption and dissociation of O$_2$ and H$_2$O molecules on the surface of 2D aza-triphenylene monolayer through first principles calculations in combination with climbing image nudged elastic band (CINEB) method. The results indicates that both the O$_2$ and H$_2$O molecules weakly interact over the monolayer surface with an adsorption energy -0.16 eV and -0.37 eV respectively. In contrast, both the molecules exhibit resistance for dissociation due to the formation of energy barriers. The transition path indicates that molecular oxygen experience two energy barriers (0.16 ev and 1.22 eV) before getting dissociated atomic oxygen. However, the dissociation of H$_2$O requires larger energy barrier (2.3 eV and 0.86 eV) due to breaking of covalent bonds and transfer of hydrogen. The strong chemical adsorption of atomic oxygen and H$^+$/OH$^-$ ions is due to the significant charge transfer from monolayer to the adsorbate as evidenced from the charge density difference and Bader charge analysis. Moreover, the dissociated configuration exhibit a larger band gap as compared to the pristine aza-triphenylene due to the strong hybridization between the p states of carbon and oxygen. our work predicts the robustness of azatriphylene monolayer against oxygen/water exposer thus ensuring their stability for device applications using these materials.

cond-mat.mtrl-sci↗

arXiv2025

Computational Insights into Defect Induced Modulation in Electronic Properties of 2D Nitride Monolayers

Two-dimensional (2D) nitride materials such as hexagonal boron nitride (h-BN), graphitic carbon nitride (g-C$_3$N$_4$), and beryllonitrene (BeN$_4$) have emerged as promising candidates for next generation electronic, optoelectronic, and energy applications due to their unique structural and electronic properties. This study presents a systematic investigation of the effects of vacancy defect, specifically the role of nitrogen and constituent atom vacancies on the electronic properties of these materials. Our findings reveal that the introduction of nitrogen vacancies significantly alters the electronic characteristics of these materials. In h-BN, the presence of a nitrogen monovacancy significantly lowers the work function from 5.97 eV to 3.45 eV, one of the lowest values reported for any 2D material. Additionally, this defect reduces the band gap from 4.6 eV to 0.64 eV, driving the material toward half-metallic behavior. This is accompanied by the emergence of flat bands near the Fermi level, indicative of strong electron-electron interactions. In g-C$_3$N$_4$, nitrogen vacancies lead to a decrease in work function and band gap, with double nitrogen vacancies rendering the material nearly metallic. In BeN$_4$, nitrogen vacancies result in minimal charge redistribution and a slight increase in work function, highlighting the material's unique electronic behavior. These results underscore the potential of vacancy engineering in tuning the electronic properties of 2D nitride materials, offering avenues for the design of materials with tailored work functions and band gaps for applications in optoelectronics, spintronics, and catalysis.

cond-mat.mtrl-sci↗

arXiv2025

Theoretical prediction of a novel Pt3Sn2S2 as a Nonmagnetic Weyl Semimetal in Kagome System

We present a detailed theoretical study of Pt3Sn2S2 a layered kagome type material inspired by recent investigation of Co3Sn2S2 reported in [Nature Communication 11, 3985 (2020) whose physical properties remain largely unexplored. Thermodynamic stability was confirmed via formation energy calculations while mechanical stability was evaluated using Voigt Reuss Hill approximation and elastic stability condition. Dynamical and thermal stability were validated through Phonon dispersion and Ab Initio Molecular Dynamics simulations with Pughs criterion classifying the material as ductile. Spin orbit coupling induced band splitting, giving rise to Weyl points and a Weyl semimetal phase accompanied by a SOC driven transition from non relativistic band touching to relativistic band touching making a topological phase shift. Under applied pressure, the coupling of spin and valley degrees of freedom generates spin valley intertwined Dirac cones enabling tunable electronic properties for spintronic and valleytronic applications. Boltzman transport calculations using AMSET reveal a high Seebeck coefficient with SOC and low thermal conductivity highlighting its potential for high performance thermoelectric devices.

cond-mat.str-el↗

arXiv2024

Biphenylene Nanoribbon as Promising Electrocatalyst for Hydrogen Evolution

Designing efficient, metal free, and in-expensive catalyst for electrochemical hydrogen evolution reaction (HER) is crucial for large scale clean and green energy production. Recently synthesized 1D Biphenylene nanoribbons (BPRs) display few exciting properties originating from the unique co-existence of 4, 6 and 8 coordinated carbon rings. Here, we present a first principles calculation of the electronic structure and electrocatalytic activity of various sized N-BPRs (N indicates the width). The electrocatalytic performance is evaluated based on several descriptors including electronic property, carrier mobility, Gibbs free energy ($Δ$G$_{HER}$), exchange current density etc. The electronic properties are crucially sensitive to the width (N) of BPRs transiting it from semiconducting to metallic nature at N=18. The p$_z$ orbitals of C-atoms from the central tetragonal rings are mainly responsible for the decrease in band gap with increasing width. The room temperature electron mobility is found to be as high as $\sim6.3\times$10$^4$ cm$^2$V$^{-1}$s$^{-1}$, while hole mobility is relatively lower in magnitude. Gibbs free energy also depends sensitively on the width of BPRs as evident from the p-band center analysis. We propose 15-BPR as the most promising candidate for electrocatalytic activity with extremely small overpotential ($\approx$0.005 V) and a high exchange current density, much better than the state-of-the-art Pt(111). A close inspection of the elementary reactions of HER (Volmer, Heyrovsky and Tafel) confirms Volmer-Tafel mechanism to be most dominant on 15-BPR with Tafel as the rate-determining step with a barrier of 0.56 eV. The present study provides a deeper insight into the excellent HER catalytic activity of a newly synthesized BPR which is inexpensive and is expected to hasten experimental validation towards H$_2$ production.

cond-mat.mtrl-sci↗

arXiv2023

High Capacity Hydrogen Storage on Zirconium decorated γ-graphyne: A systematic first-principles study

In this work, we investigate the hydrogen-storage properties of Zr-decorated $γ$-graphyne monolayer employing Density Functional Theory (DFT) for green energy storage. We predict that each Zr atom decorated on graphyne sheet (2D) can adsorb up to seven H$_2$ molecules with an average adsorption energy of -0.44 eV/H$_2$, leading to a hydrogen gravimetric density of 7.95 wt%, and desorption temperature of 574 K, particularly suited to fuel-cell applications. Decorated Zr atom strongly attached to graphyne due to charge transfer from Zr to graphyne sheet. Hydrogen molecules adsorb on Zr decorated graphyne with Kubas type of interaction. The 4.05 eV diffusion energy barrier between Zr decorated position, and its neighboring pores may avoid the metal-metal (Zr-Zr) clustering. The stability of Zr+$γ$-graphyne is confirmed by performing ab-initio molecular dynamics simulations at room temperature and at estimated average desorption temperature. Hence, our calculations show Zr functionalized on $γ$-graphyne could be a promising solid-state hydrogen storage material.

cond-mat.mtrl-sci↗

arXiv2023

Potential reversible hydrogen storage in Li-decorated carbon allotrope PAI-Graphene: A first-principles study

Two-dimensional porous carbon nanomaterials are proven to be promising hydrogen storage substrates as they possess high surface area, large number of active sites, low molecular mass, and hydrogen molecules can be adsorbed on both sides of these materials. By performing first-principles density functional theory-based calculations, we report ultrahigh reversible hydrogen uptake in lithium decorated 2D carbon allotrope PAI-graphene, which is formed of a regular pattern of polymerized as-indacenes (PAI). We found that a single unit cell of PAI-graphene can be decorated by 8 Li atoms, in which each Li atom can reversibly adsorb 4 hydrogen molecules, leading to 15.7 % of H uptake, remarkably higher than the DOE demand of 6.5 %. Li atom donates its valence 2s-electron to PAI-graphene and gets ionized. The adsorption energies of the various H2 attached to Li-atom are found to be suitable for reversible use during practical applications. Hydrogen molecules get attached to the ionized metal atom by electrostatic interactions. An energy barrier of 1.48 eV is present for the diffusion of Li atoms between the two most stable adsorption sites which justifies the absence of the clustering of Li atoms.

cond-mat.mtrl-sci↗

arXiv2023

Enhancing the ultrafast third order nonlinear optical response by charge transfer in VSe2-reduced graphene oxide hybrid

Nonlinear optical phenomena play a critical role in understanding microscopic light-matter interactions and have far-reaching applications across various fields, such as biosensing, quantum information, optical switching, and all-optical data processing. Most of these applications require materials with high third-order absorptive and refractive optical nonlinearities. However, most materials show weak nonlinear optical responses due to their perturbative nature and often need to be improved for practical applications. Here, we demonstrate that the charge donor-acceptor hybrid of VSe2-reduced graphene oxide (rGO) hybrid exhibits enhanced ultrafast third-order absorptive and refractive nonlinearities compared to the pristine systems, at least by one order of magnitude. Through density functional theory and Bader charge analysis, we elucidate the strong electronic coupling in the VSe2-rGO hybrid, involving the transfer of electrons from VSe2 to rGO. Steady-state and time-resolved photoluminescence (PL) measurements confirm the electronic coupling and charge transfer. Furthermore, we fabricate an ultrafast optical limiter device with better performance parameters, such as an onset threshold of 2.5 mJ cm-2 and differential transmittance of 0.42.

physics.optics↗

arXiv2023

Highly Efficient Hydrogen Storage of Sc Decorated Biphenylene Monolayer near Ambient-temperature: An Ab-initio Simulation

The energy demands for the growing development of society need to be catered with alternative and green fuels like hydrogen energy for a lasting and sustainable culture. One essential component of the hydrogen economy is the efficiency of its storage. We have studied the hydrogen-storage capability on a recently synthesized Biphenylene (BPh) decorated with Sc using the first-principles density functional theory (DFT) and ab-initio molecular dynamics (AIMD) techniques. Scandium attaches BPh sheet strongly with binding energy -3.84 eV, and single Sc decorated on BPh can absorb a maximum of five H$_2$ molecules resulting in a high gravimetric weight percentage of 11.07, which is significantly higher than DoE's ultimate criteria (6.5 wt%). Using van't Hoff equation, strongly and weakly attached hydrogens correspond to desorption temperatures of 200 K and 397 K with an average of 305 K. The high binding of Sc to BPh is due to charge donation of 3d orbital of Sc to 2p orbital of C. The interactions between absorbed H$_2$ and BPh+Sc are due to charge transfer from 3d-orbital of Sc to $σ$* bond of H$_2$ molecules and backdonation from $σ$ bond of H$_2$ to empty 3d-orbital of Sc known as Kubas type interaction. Furthermore, phonon and AIMD simulation confirm BPh+Sc stability, and the presence of an energy barrier shows no probability of Sc-Sc clustering on BPh. So theoretically stable BPh+Sc showing high gravimetric weight percentage with an average 305 K desorption temperature, might be a potential candidate for solidstage hydrogen devices.

cond-mat.mtrl-sci↗

arXiv2023

Room Temperature d$^0$ Ferromagnetism in Carbon Doped LaH$_3$: Insights From Density Functional Theory Simulations

Employing the state-of-the-art Density Functional Theory with both GGA and hybrid HSE06 functional along with the incorporation of spin-orbit coupling, we have engineered stable room temperature ferromagnetism in non-magnetic LaH$_3$ through C substitution at octahedral and tetrahedral H sites where the induced magnetic moment is mostly contributed by 2p orbital of C atom. It is interesting that the magnetic signature is switched on with an impurity concentration as low as 1.04 at% with a magnetic moment of $\approx$ 1.0 $μ_B$ per impurity, where the localized behavior of the 2p states of C along with significant exchange splitting energy can be attributed as the origin of the induced magnetic moment. The verification of the Stoner criterion in the material further confirmed the onset of ferromagnetism in the system, and the computed Curie temperature is found to be well above room temperature. Reduced formation energy and requirement of lower impurity concentration ensure practical feasibility towards a spintronic device where room temperature ferromagnetism is established from the non-magnetic host and the dopant.

cond-mat.mtrl-sci↗

arXiv2022

Remarkable enhancement in catechol sensing by the decoration of selective transition metals in biphenylene sheet: A systematic first-principles study

Motivated by the recent successful synthesis of biphenylene structure [Science 372, (2021), 852], we have explored the sensing properties of this material towards the catechol biomolecule by performing the first-principles density functional theory and molecular dynamics simulations. Pristine biphenylene sheet adsorbs catechol molecule with a binding energy of -0.35 eV, which can be systematically improved by decorating the transition metals (Ag, Au, Pd, and Ti) at various possible sites of biphenylene. It is observed that the catechol molecule is adsorbed on Pd and Ti-decorated biphenylene sheets with strong adsorption energies of -1.00 eV and -2.54 eV, respectively. The interaction of the catechol molecule with biphenylene and metal-decorated biphenylene is due to the charge transfer from the O-2p orbitals of the catechol molecule to the C-2p orbitals of biphenylene and d-orbitals of metals in metal-decorated biphenylene, respectively. From the Bader charge calculation, we found that 0.05e amount of charge is transferred from the catechol molecule to pristine biphenylene, which gets almost double (~0.1e) for the Ti-decorated biphenylene sheet. The diffusion energy barrier for the clustering of the Pd and Ti atoms comes out to be 2.39 eV and 4.29 eV, computed by performing the climbing-image nudged elastic band calculations. We found that the catechol molecule gets desorbed from the pristine biphenylene sheet even at 100 K but remains attached to metal (Pd, Ti) decorated biphenylene sheets at room temperature by performing the ab-initio molecular dynamics simulations. The Ti-decorated biphenylene sheet has more sensitivity toward catechol adsorption while the Pd-decorated biphenylene sheet has a suitable recovery time at 500 K. The results suggest that the Pd and Ti-decorated biphenylene sheets are promising materials for catechol detection.

cond-mat.mtrl-sci↗

arXiv2022

Influence of compressive strain on the hydrogen storage capabilities of graphene: A density functional theory study

Pristine graphene is not suitable for hydrogen storage at ambient conditions since it binds the hydrogen molecules only by van der Waals interactions. However, the adsorption energy of the hydrogen molecules can be improved by doping or decorating metal atoms on the graphene monolayer. The doping and decoration processes are challenging due to the oxygen interference in hydrogen adsorption and the clustering issue of metal atoms. To improve the hydrogen adsorption energy in pristine graphene, we have explored the hydrogen storage capabilities of graphene monolayer in the presence of compressive strain. We found that at 6 % of biaxial compressive strain, a 4*4*1 supercell of graphene can adsorb 10 H$_2$ molecules above the graphene surface. The average binding energy of H$_2$ for this configuration is found to be -0.42 eV/H$_2$, which is very suitable for reversible hydrogen adsorption. We propose that a 4*4*1 supercell of graphene can adsorb a total number of 20 H$_2$ molecules leading to a high hydrogen uptake of 9.4 %. The interaction between orbitals of carbon and hydrogen atoms and the charge transfer process have been studied by plotting the partial density of states and surface charge density plots. The electronic density around the C-C bonds of graphene increases in the presence of compressive strain, due to which hydrogen molecules are strongly adsorbed.

cond-mat.mtrl-sci↗

arXiv2022

Prediction of a Novel 2D Porous Boron Nitride Material with Excellent Electronic, Optical and Catalytic Properties

Holey graphyne (HGY) is a recently synthesized two-dimensional semiconducting allotrope of carbon composed of a regular pattern of six and eight-vertex carbon rings. In this study, based on first-principles density functional theory and molecular dynamics simulations, we predict a similar stable porous boron nitride holey graphyne-like structure that we call BN-holey-graphyne (BN-HGY). The dynamical and thermal stability of the structure at room temperature is confirmed by performing calculations of the phonon dispersion relations, and also ab-initio molecular dynamics simulations. BN-HGY structure has a wide direct bandgap of 5.18 eV, which can be controllably tuned by substituting carbon, aluminum, silicon, and phosphorus atom in place of sp and sp$^2$ hybridized boron and nitrogen atoms of BN-HGY. We have also calculated the optical properties of the HGY and BN-HGY structures for the first time and found that the optical absorption spectra of these structures span full visible and a wide range of ultraviolet regions. We have found that the Gibbs free energy of the BN-HGY structure for the hydrogen adsorption process is very close to zero (-0.04 eV) and, therefore, the BN-HGY structure can be utilized as a potential catalyst for HER. Therefore, we propose that the boron nitride analog of holey graphyne can be synthesized and that it has a wide range of applications in nanoelectronics, optoelectronics, spintronics, ultraviolet laser, and solar cell devices.

cond-mat.mtrl-sci↗

arXiv2022

Ultrahigh reversible hydrogen storage in K and Ca decorated 4-6-8 biphenylene sheet

By applying density functional theory (DFT) and ab-initio molecular dynamics (AIMD) simulations, we predict the ultrahigh hydrogen storage capacity of K and Ca decorated single-layer biphenylene sheet (BPS). We have kept various alkali and alkali earth metals, including Na, Be, Mg, K, Ca, at different sites of BPS and found that K and Ca atoms prefer to bind individually on the BPS instead of forming clusters. It was found that 2x2x1 supercell of biphenylene sheet can adsorb eight K, or eight Ca atoms, and each K or Ca atom can adsorb 5 H$_2$, leading to 11.90 % or 11.63 % of hydrogen uptake, respectively, which is significantly higher than the DOE-US demands of 6.5 %. The average adsorption energy of H$_2$ for K and Ca decorated BPS is -0.24 eV and -0.33 eV, respectively, in the suitable range for reversible H$_2$ storage. Hydrogen molecules get polarized in the vicinity of ionized metal atoms hence get attached to the metal atoms through electrostatic and van der Waals interactions. We have estimated the desorption temperatures of H$_2$ and found that the adsorbed H$_2$ can be utilized for reversible use. We have found that a sufficient energy barrier of 2.52 eV exists for the movement of Ca atoms, calculated using the climbing-image nudged elastic band (CI-NEB) method. This energy barrier can prevent the clustering issue of Ca atoms. The solidity of K and Ca decorated BPS structures were investigated using AIMD simulations.

cond-mat.mtrl-sci↗