▎ 摘　　要

Epitaxially-oriented large-scale monolayer molybdenum disulfide (MoS2) grown directly on graphene (Gr) with an atomic-clean interface draws intensive interest in both areas of fundamental sciences and electronic-device applications. In general, however, synthetic characteristics and bandgap-related properties of MoS2 crystals can be varied by the selection of substrates that support Gr, and mechanisms that govern these phenomena remain unclear. Here, by means of scanning tunneling microscope and spectroscopy (STM/STS) and photoluminescence (PL) measurements, we have discovered that considerably-strained Gr can strongly affect the epitaxy of MoS2 crystals and enhance the interlayer electronic coupling between monolayer MoS2 and its Gr-platinum (Pt) substrate, leading to the stack of MoS2 layers and a narrowing direct bandgap of monolayer MoS2. Our studies shed light on growing large-scale MoS2 films on Gr and the bandgap modulation in these heterostructures. (C) 2018 Elsevier Ltd. All rights reserved.