On Rh(111), a monolayer of hexagonal boron nitride (h-BN, isoelectronic with graphene) forms a so-called nanomesh superstructure [1], characterized by a 3.2-nm lattice constant and strong electronic corrugation, which can be used for trapping atoms and molecules [2,3]. Here, we show that hydrogen underpotential deposition (H upd) is easier on h-BN/Rh(111) than on the naked substrate [4], and leads to submonolayer quantities of hydrogen intercalated between the h-BN overlayer and Rh(111), as demonstrated by electrolyte-to-vacuum transfer experiments and thermal desorption spectroscopy. In situ STM measurements reveal that the intercalation lifts the corrugation of the nanomesh, and that this process is fully reversible under potential control. Copper upd is used to quantify the defect density in the nanomesh, and to increase the understanding of the electrochemical window where the nanomesh is stable. By measuring dynamic contact angles of an electrolyte drop (see Figure), we show that the microscopic change within the 2-dimensional material leads to a macroscopic effect related to a 10% change in adsorption energy [4]. The static friction on the other hand, which can be extracted by extending the Young equation for non-equilibrium effects, remains unchanged for the surface in the two states.

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[4] S.F.L. Mertens, A. Hemmi, S. Muff, O. Gröning, S. De Feyter, J. Osterwalder, T. Greber, Nature 534 (2016) 676–679.