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

TL;DR

This work investigates the potential of 2D borospherene (2D–B40) as a platform for detecting and capturing toxic gases using density functional theory (DFT). It quantitatively analyzes adsorption energies, charge transfer, and work-function shifts for CO, NO, NH3, and SO2, identifying physisorption for CO and chemisorption for the others, with $E_{ ext{ads}}$ values of $-0.16$, $-2.24$, $-1.47$, and $-1.51$ eV respectively and distinct charge-transfer signatures ($\Delta Q$ values). The study further reveals substantial work-function modulations, particularly a $\\Delta\\Phi$ up to $14.56\\%$ for SO2, and confirms material stability via DFPT phonons and AIMD at 300 K, including spontaneous SO2 decomposition on the surface. Collectively, these findings position 2D–B40 as a promising dual-function platform for both sensing and environmental remediation of toxic gases, driven by strong orbital hybridization and charge-transfer mechanisms.

Abstract

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.

Figures (9)

• Figure 1: Structural and thermal stability analysis of the 2D–B40 network. (a) Top view and (b) side view of a $2\times2\times1$ supercell illustrating the alternation of hexagonal and heptagonal boron rings (green spheres). (c) Total energy evolution during 5 ps of AIMD simulation run at 300 K.
• Figure 2: (a) Phonon dispersion of the 2D–B40 network along $\Gamma\text{–}M\text{–}K\text{–}\Gamma$, showing the absence of imaginary modes and confirming dynamical stability. (b) Electronic band structure (left) plotted with the Fermi level at 0 eV (red dashed line) and the projected density of states (right).
• Figure 3: Top view of the 2D–B40 network highlighting the three adsorption sites considered: S1 (blue cross) atop a boron atom, S2 (green cross) at the center of a heptagonal ring, and S3 (orange cross) at a bridge between two boron atoms. The crystallographic axes $a$ and $b$ are indicated.
• Figure 4: Adsorption energies ($E_\mathrm{ads}$) of CO, NO, NH$_3$ and SO$_2$ at sites S1 (top of B), S2 (hollow center) and S3 (bridge) on the 2D–B$_{40}$ network. The red dashed line at $|E_\mathrm{ads}|=0.5$ eV separates physisorption (above) from chemisorption (below).
• Figure 5: Side views of the most stable adsorption geometries on the 2D–B40 network: (a) CO at the S3 bridge site (B–C distance 2.96 Å); (b) NO atop a boron atom at S1 (B–N distance 1.45 Å); (c) NH$_3$ at S3 (B–N distance 1.62 Å); and (d) SO$_2$ at S3 (B–S distance 1.51 Å).