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.

中文翻译：

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MoS2on 化学和热还原氧化石墨烯纳米片的直接 CVD 生长以改善光响应

在石墨烯或氧化石墨烯（GO）上直接进行过渡金属二硫化碳（TMDC）的化学气相沉积（CVD），可实现范德华异质结构（vdWHs）的可扩展生产。在此，考虑到 TMDC 的 CVD 生长在很大程度上取决于基材的表面性质，我们将化学还原的 GO (CrGO) 和热还原的 GO (TrGO) 作为基材进行比较，以在没有晶种促进剂的情况下诱导 MoS ₂的 CVD 生长。在单层 (1L) 到三层 CrGO 和 TrGO 纳米片上，在 CrGO 上发现比在 TrGO 上更多的三角形 MoS ₂薄片。这是因为具有较少表面缺陷的 CrGO 可以促进 MoS ₂的生长与通常带有更多缺陷的 TrGO 相比。当CrGO和TrGO纳米片的厚度超过五层时，这种差异并不明显。作为演示，在蓝色和红色激光照射下，与 1L CrGO 和 TrGO 纳米片相比，获得的 MoS ₂ @1L-CrGO 和 MoS ₂ @1L-TrGO vdWH 纳米片显示出更高的光敏性。特别是，硫化钼₂ @ 1L-CRGO用的MoS更高密度的₂显示出比的MoS较大光敏性₂ @ 1L-TRGO。此外，将 MoS ₂ @1L-CrGO 和 MoS ₂ @1L-TrGO vdWH 纳米片卷成 MoS ₂ @CrGO 和 MoS ₂@TrGO vdWH nanoscrolls 进一步增强了它们的光敏性，这主要是由于滚动结构中存在多个 vdWH 界面。我们的工作表明，化学改性氧化石墨烯表面缺陷的减少促进了 MoS ₂的沉积以形成 vdWHs 和相关的涡旋结构，这对光电子学和柔性电子学很有前景。