Effect of the Number of Graphene Layers on the Electron Transfer Kinetics at Metal/Graphene Heterostructures

•Metal substrate catalyzes electron transfer due to the hybridization of the metal and graphene states.•Hybridization provides a more efficient interaction of the reactant with metal.•Electron transfer at metal-supported few-layer graphene is nonadiabatic.•Electron transfer at metal-supported single-layer graphene is adiabatic.