Synthesis of Wet-Chemically Prepared Porous-Graphene Single Layers on Si/SiO2 Substrate Increasing the Photoluminescence of MoS2 in Heterostructures

Abstract

Wet-chemical generation of pores in graphene is a challenging synthetic task. Although graphene oxide is available in large quantities and chemically diverse, extended lattice defects already present from synthesis hamper the controlled growth of pores. However, membrane, energy, or nanoelectronic applications essentially require uniform pores in applications. Here, oxo-functionalized graphene (oxoG), a type of graphene oxide with a controlled density of vacancy defects, is used as starting material. Pores in graphene are generated from potassium permanganate treated oxoG and heating from room temperature to 400 °C. With etching time, the size of pores increases and pore-diameters of, for example, 100–200 nm in majority become accessible. The experiments are conducted on the single-layer level on Si/SiO2 wafers. Flakes remain stable on the µm scale and do not fold. The process leads to rims of pores, which are functionalized by carbonyl groups in addition to hydroxyl and carboxyl groups. In addition, it is found that heterostructures with intrinsically n-doped MoS2 can be fabricated and photoluminescence (PL) measurements reveal a 10-fold increased PL. Thus, graphene with pores is a novel highly temperature-stable electron-accepting 2D material to be integrated into van der Waals heterostructures.