Stabilization of hBN/SiC heterostructures with vacancies and transition-metal atoms

When two-dimensional atomic layers of different materials are brought into close proximity to form van der Waals (vdW) heterostructures, interlayer interactions can strongly influence their physicochemical properties. These effects are particularly pronounced when the interface exhibits local order and near-perfect structural alignment, giving rise to moiré patterns. Using density-functional theory calculations, we investigate a bilayer heterostructure composed of hexagonal boron nitride (hBN) and silicon carbide (SiC). We predict that introducing a boron vacancy, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msub> <a:mi>V</a:mi> <a:mi mathvariant="normal">B</a:mi> </a:msub> </a:math> , at specific lattice sites alters the interlayer interaction from weak vdW coupling to localized silicon-nitrogen covalent bonding. Motivated by this mechanism, we examine the binding of transition-metal adatoms and identify principles for enhancing surface reactivity and stabilizing isolated single-metal atoms. Machine-learning molecular dynamics at finite temperature further demonstrate rapid and effectively irreversible trapping of Cu at <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:msub> <c:mi>V</c:mi> <c:mi mathvariant="normal">B</c:mi> </c:msub> </c:math> sites, and show how the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:msub> <e:mi>V</e:mi> <e:mi mathvariant="normal">B</e:mi> </e:msub> </e:math> :Cu ratio governs the transition from single-atom isolation to vacancy-directed aggregation. These results suggest the hBN/SiC heterostructure as a versatile platform for atomically precise transition-metal functionalization, with implications for catalytic energy-conversion materials.