Joongjai Panpranot | Searcharxiv

arXiv2026

Two-Dimensional Hexagonal BX3 (X = P, As) Monolayers as High-Capacity, Fast-Charging Anode Platforms for Lithium- and Sodium-Ion Batteries

The rapid advancement of alkali-metal ion batteries demands robust anode platforms combining high specific capacities with rapid charge-discharge kinetics. Using first-principles density functional theory (DFT), we systematically evaluate two-dimensional (2D) hexagonal BX3 (X = P, As) monolayers as high-performance dual-use anodes for lithium-ion (LIBs) and sodium-ion batteries (SIBs). Both metallic host architectures display strong thermodynamic affinities for Li+ and Na+ adsorption, favoring the hollow H3 site through synergistic ionic charge transfer and orbital hybridization. Climbing image nudged elastic band (CI-NEB) calculations reveal low direct H3 -> H3 diffusion barriers: 0.40 eV (BP3) and 0.26 eV (BAs3) for Li+, and 0.26 eV (BP3) and 0.19 eV (BAs3) for Na+, confirming exceptional high-rate kinetics. Thermodynamic convex hulls establish maximum stable lithiation at Li3BX3, yielding low average operating potentials of 0.39 V (BP3) and 0.35 V (BAs3) alongside theoretical specific capacities of 775 mAh/g and 341 mAh/g, respectively, with BP3 doubling commercial graphite (372 mAh/g). For SIBs, multi-layer sodiation expands storage up to Na15BP3 and Na12BAs3, delivering ultrahigh capacities of 3875 mAh/g (BP3) and 1365 mAh/g (BAs3) at low voltages of 0.18 V and 0.15 V. Crucially, projected density of states (PDOS) analyses confirm that both frameworks preserve intrinsic metallic conductivity throughout all charging stages. These combined properties establish 2D BX3 monolayers as outstanding, structurally resilient anode candidates for next-generation LIB and SIB energy storage technologies.

cond-mat.mtrl-sci↗

arXiv2026

Mechanism-driven CO2 Capture and Activation on Two-dimensional Transition-metal Diborides

The urgent need to mitigate rising atmospheric CO2 levels motivates the search for stable, efficient, and tunable adsorbent materials. In this study, we employ first-principles density functional theory to investigate the adsorption of CO2 molecules on two-dimensional hexagonal transition-metal diboride monolayers, M2B2 (M = Sc, Y, Ti, Zr, Nb). The adsorption energies, structural distortions, and bonding characteristics are systematically analyzed to understand how the metal center governs CO2 activation. The calculated adsorption energies range from -1.84 to -2.16 eV (or -1.98 to -4.42 eV), with Ti2B2 and Sc2B2 exhibiting the strongest CO2 binding, while Y2B2, Zr2B2, and Nb2B2 show moderately strong chemisorption. Adsorption induces significant molecular activation, evidenced by elongated C-O bonds (1.27-1.29 Angstrom) and bent O-C-O angles (129-132 degrees), compared to the linear gas-phase configuration (1.17 Angstrom, 180 degrees). Charge analysis further reveals substantial electron transfer from the monolayer to CO2, consistent with strong chemisorption and structural deformation. Correspondingly, the shift toward less negative IpCOHP(Ef) values indicates a pronounced weakening of the internal C-O bonds, reflecting increased population of antibonding pi* orbitals. Ab initio molecular dynamics simulations show that the activated CO2 species is thermally sensitive: while most M2B2 surfaces retain stable adsorption at 300 K, Ti2B2 drives spontaneous CO2 dissociation into CO and O, revealing a temperature-assisted activation pathway. These findings highlight how the choice of transition metal tunes electronic interactions, adsorption energetics, and activation pathways on M2B2 surfaces. Overall, this work identifies two-dimensional transition-metal diborides as promising candidates for next-generation CO2 capture and activation technologies.

cond-mat.mtrl-sci↗