Growth of self-aligned single-crystal vanadium carbide nanosheets with a controllable thickness on a unique staked metal substrate

The single-crystal α-Mo₂C nanosheets was first achieved on liquid copper by chemical vapor deposition in 2015. However, the other single-crystal transition-metal carbide nanosheets have not been reported yet. Here, we demonstrate the chemical vapor deposition of single-crystal VC nanosheets with the maximum size of 77 μm on a unique stacked metal substrate. The thickness of VC crystals can be controlled from 12 to 227 nm by changing the deposition pressure (P_d). The reduced P_d decreased the growth rate parallel and perpendicular to the [0 1¯ 1] zone axis. When the P_d was 5000 Pa, the well-aligned single-crystal VC arrays with the thickness of 12 ± 4 nm was obtained. The effect of the hydrogen flow (f) on VC morphology was also discussed. Due to the growth of VC complied to the mass-transport-limited process under high f, the VC crystals tended to be dendrite with the increase of the f. This study could pave a new way for controlling growth of transition-metal carbide nanosheets with tunable thickness and morphology.