Boron Fullerenes: From Theoretical Predictions to Experimental Reality (2506.20032v1)

Abstract: We present a comprehensive first-principles investigation of boron fullerenes and two-dimensional boron sheets, unified under a coordination-based framework. By classifying over a dozen boron nanostructures, including B${12}$, B${40}$, B${65}$, B${80}$, and B${92}$, according to their local atomic environments (4-, 5-, and 6-fold coordination), we identify clear trends in structural stability, electronic properties, and magnetism. A universal energetic scaling relation $E_c(n) = a/n^b + E_c^{sheet}$ (with $b \approx 1$) captures the convergence of fullerene cohesive energies toward those of 2D boron phases. Notably, we establish one-to-one structural correspondences between select cages and experimentally accessible borophenes: B${40}$ mirrors the $\chi_3$-sheet, B${65}$ the $\beta{12}$-sheet, B${80}$ the $\alpha$-sheet, and B${92}$ the $bt$-sheet. These clusters also exhibit large HOMO-LUMO gaps (e.g., $E_g = 1.78$ eV for B${40}$, 1.14 eV for B${92}$), contrasting with the metallicity of their 2D counterparts and, in the case of B${65}$, spontaneous spin polarization ($M = 3 \, \mu_B$). Our findings provide a predictive strategy for designing boron nanostructures by leveraging coordination fingerprints, and are further validated by the recent experimental synthesis of the B${80}$ cage. This work bridges zero- and two-dimensional boron chemistry, offering a roadmap for the future synthesis and application of boron-based materials.