van der Waals Epitaxy of MoS₂ Layers Using Graphene As Growth Templates

TLDR

The authors develop a graphene‑covered Cu foil template method to synthesize MoS₂/Graphene hybrid heterostructures. MoS₂ is grown by chemical vapor deposition on graphene, where ammonium thiomolybdate precursor is transported at room temperature, then annealed and thermally decomposes to self‑assemble into single‑crystalline hexagonal flakes that can coalesce into continuous films. The method achieves MoS₂/Graphene hybrids at only 400 °C, yielding single‑crystalline flakes and continuous films that hold promise for optical, electronic, and catalytic applications.

Abstract

We present a method for synthesizing MoS2/Graphene hybrid heterostructures with a growth template of graphene-covered Cu foil. Compared to other recent reports,(1, 2) a much lower growth temperature of 400 °C is required for this procedure. The chemical vapor deposition of MoS2 on the graphene surface gives rise to single crystalline hexagonal flakes with a typical lateral size ranging from several hundred nanometers to several micrometers. The precursor (ammonium thiomolybdate) together with solvent was transported to graphene surface by a carrier gas at room temperature, which was then followed by post annealing. At an elevated temperature, the precursor self-assembles to form MoS2 flakes epitaxially on the graphene surface via thermal decomposition. With higher amount of precursor delivered onto the graphene surface, a continuous MoS2 film on graphene can be obtained. This simple chemical vapor deposition method provides a unique approach for the synthesis of graphene heterostructures and surface functionalization of graphene. The synthesized two-dimensional MoS2/Graphene hybrids possess great potential toward the development of new optical and electronic devices as well as a wide variety of newly synthesizable compounds for catalysts.