Abstract

As a new member of the MXene group, 2D Mo 2 C has attracted considerable interest due to its potential application as electrodes for energy storage and catalysis. The large‐area synthesis of Mo 2 C film is needed for such applications. Here, the one‐step direct synthesis of 2D Mo 2 C‐on‐graphene film by molten copper‐catalyzed chemical vapor deposition (CVD) is reported. High‐quality and uniform Mo 2 C film in the centimeter range can be grown on graphene using a Mo–Cu alloy catalyst. Within the vertical heterostructure, graphene acts as a diffusion barrier to the phase‐segregated Mo and allows nanometer‐thin Mo 2 C to be grown. Graphene‐templated growth of Mo 2 C produces well‐faceted, large‐sized single crystals with low defect density, as confirmed by scanning transmission electron microscopy (STEM) measurements. Due to its more efficient graphene‐mediated charge‐transfer kinetics, the as‐grown Mo 2 C‐on‐graphene heterostructure shows a much lower onset voltage for hydrogen evolution reactions as compared to Mo 2 C‐only electrodes.