Substrate dependence of graphene reactivity towards hydrogenation

The ability of functionalize graphene with several methods, such as radical reactions, cyclo-additions, hydrogenation and oxidations, allows this material to be used in a large range of applications. In this framework, it is essential to be able to control the efficiency and stability of the functionalization process - this requires understanding how the graphene reactivity is affected by the environment, including the substrate.
In this work we provide an insight on the substrate dependence of graphene reactivity towards hydrogenation by comparing three different substrates: silicon, hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2). Although MoS2 and h-BN have flatter surfaces than silicon, we found that the H coverage of graphene on h-BN is about half of the H coverage on graphene on both silicon and MoS2. Therefore, graphene shows strongly reduced reactivity towards hydrogenation when placed on h-BN. The difference in hydrogenation reactivity between h-BN and MoS2 may indicate a stronger van der Waals force between graphene and h-BN, compared to MoS2, or may be related to the chemical properties of MoS2, which is a well-known catalyst for hydrogen evolution reactions.