▎ 摘　　要

From the study of precious metal/graphene heterobilayers instead of commercial Pt/C catalysts, we propose a strategy for improving the performance/cost ratio of metals in electrocatalysis. Results from the Rh/graphene bilayer show that the Rh atoms that directly interact with graphene occupy most of the area of the supported metal sheet, and they exhibit better hydrogen evolution reaction (HER) activity than Rh and even than Pt. The interlayer charge transfer, rather than the intralayer charge transfer, leads to the downshift of the d-states of these Rh atoms in energy and weakens the H-Rh binding. This allows the HER process to be almost thermo-neutral. Support interactions determine whether the interlayer charge transfer or the intralayer charge transfer is dominant in the bilayer and surface corrugations on the two sheets. A different structure-activity relationship is present in two-dimensional systems. This study on the corrugation-sensitive HER activity and the activation mechanism of Rh/graphene heterobilayers is also helpful for the design of more ultrathin precious or non-precious metal/graphene heterostructures used as electrodes in water electrolysis.