▎ 摘　　要

The direct chemical vapor deposition (CVD) of transition metal dichalcogenides (TMDCs) on graphene or graphene oxide (GO) allows for the scalable production of van der Waals heterostructures (vdWHs). Herein, considering that the CVD growth of TMDCs depends largely on the surface property of the substrate, we compared chemically reduced GO (CrGO) and thermally reduced GO (TrGO) as substrates to induce the CVD growth of MoS2 without a seeding promoter. On monolayer (1L) to three-layer CrGO and TrGO nanosheets, more triangular MoS2 flakes were found on CrGO than on TrGO. This is because CrGO with less surface defects could promote the growth of MoS2 as compared to TrGO, which normally carries more defects. Such a difference was not obvious when the thickness of CrGO and TrGO nanosheets exceeded five layer. As a demonstration, the obtained MoS2@1L-CrGO and MoS2@1L-TrGO vdWH nanosheets showed much higher photosensitivities as compared to the 1L CrGO and TrGO nanosheets under both the blue and red laser irradiation. In particular, MoS2@1L-CrGO with a higher density of MoS2 showed larger photosensitivity than MoS2@1L-TrGO. In addition, rolling up the MoS2@1L-CrGO and MoS2@1L-TrGO vdWH nanosheets into MoS2@CrGO and MoS2@TrGO vdWH nanoscrolls further enhanced their photosensitivities, largely due to the presence of multiple vdWH interfaces in the scrolled structure. Our work demonstrates that the reduction in surface defects of chemically modified graphene oxide promotes the deposition of MoS2 to form vdWHs and related scroll structures, which are promising for optoelectronics and flexible electronics.