Catalytic kinetic growth of a half-metallic hexagonal boron nitride-graphene lateral heterostructure using transition metal single-atom catalysts on Rh(111)†

Deciphering the precise catalytic growth mechanism of atomically thin graphene-based lateral heterostructures is of great interest in low-dimensional physics and materials. Here, based on first-principles calculations and extensive screenings, we reveal that the deposited transition metal atoms (TM = Mn, Zr, Nb, Mo, Hf, Ta, and W), particularly Mo, act as single-atom catalysts (SACs) to effectively promote C adatom dimerization both energetically and kinetically on a C-dimer-unpreferred Rh(111) substrate. Meanwhile, the TM-SAC increases the stability of the boron-nitride (BN) dimer, which promotes rapid growth of a hexagonal boron nitride-graphene (h-BN-G) lateral heterostructure. Specifically, taking TM = Mo as a typical example, we demonstrate that the Mo–C(BN) couplings weaken the C(BN)-substrate interactions, which sharply reduces the kinetic barriers for both C and BN nucleation and migration in the initial stage of growing the h-BN-G lateral heterostructure on Rh(111). Interestingly, Mo-SAC can dynamically involve and migrate out of the h-BN-G interface during the growth processes for C₂ dimers as feeding blocks. Moreover, the presence of Mo-SAC can effectively tune the patching boundary of the 1D h-BN-G heterostructure, i.e., from C–N to C–B linking with half-metallicity. The present findings provide significantly new insights into controllable catalytic growth of two-dimensional (2D) lateral heterostructures with various important potential applications, such as transport in spintronic devices.