Boron doping of graphene–pushing the limit†
Boron-doped derivatives of graphene have been intensely investigated because of their electronic and catalytic properties. The maximum experimentally observed concentration of boron atoms in graphite was 2.35% at 2350 K. By employing quantum chemistry coupled with molecular dynamics, we identified the theoretical doping limit for single-layer graphene at different temperatures, demonstrating that it is possible to achieve much higher boron doping concentrations. According to the calculations, 33.3 mol% of boron does not significantly undermine thermal stability, whereas 50 mol% of boron results in critical backbone deformations, which occur when three or more boron atoms enter the same six-member ring. Even though boron is less electro-negative than carbon, it tends to act as an electron acceptor in the vicinity of C–B bonds. The dipole moment of B-doped graphene depends strongly on the distribution of dopant atoms within the sheet. Compared with N-doped graphene, the dopant–dopant bonds are less destructive in the present system. The reported results motivate efforts to synthesize highly B-doped graphene for semiconductor and catalytic applications. The theoretical predictions can be validated through direct chemical synthesis.