Chemical functionalization can effectively regulate the properties of graphene by altering π electrons, but the direct control of interlayer interaction in bilayer graphene (BLG) by such a technique remains elusive. Herein, we report an in situ observation of reversible interlayer coupling/decoupling in BLG, which is sensitive to electrochemical hydrogenation. It is found that electrochemical potential applied via an organic electrolyte containing protons causes preferential hydrogenation of one graphene layer in BLG, accompanied by the presence of new Raman modes. At the same time, the other graphene layer remains almost intact under electrochemical gating, resulting in an overall high electric conductance yet sensitive to the interlayer decoupling in BLG. With density functional theory simulations, 4H-BLG is identified as a critical intermediate structure during hydrogenation, and the van der Waals interaction in BLG is effectively modified by sp3 bonding formed on the hydrogenated layer. Our work provides new insights into the regulation of interlayer interaction through surface functionalization in van der Waals stacking materials.
Zhang et al. (Tue,) studied this question.