Interface Structure and Properties of 2D Metal-Graphene Supported on Periodically Poled Lithium Niobate

In this study, we present on the controlled growth of 2D confined metals (2D-M) under heteroepitaxial relations with single-layer graphene (Gr). Using a ferroelectric material, such as periodically polled lithium niobate (PPLN), as a support, external electric/strain fields can be applied to the surface metal via the Gr conduit. With such external fields, non-Faradaic manipulation of electrocatalytic reactions on the metal-graphene structure can be carried out. We explore the architecture of a 2D metal-graphene (2D M-Gr) on top of the PPLN to determine the impact of polarization orientation on the catalytic response of the 2DM-Gr. We conduct atomic force microscopy (AFM) measurements, piezoelectric force microscopy (PFM) and Kelvin probe force microscopy (KPFM) measurements to determine the surface morphology after graphene transfer onto the substrate as well as the polarized states of the poled domains where graphene allows these polarization effects to propagate. PFM and KPFM show that a clear domain structure propagates through the 2D M-Gr. We further present the effect of the piezo/ferroelectric field on the catalytic and electrocatalytic performance of the 2D M-Gr systems and the efficacy, in general of proximity control of catalytic properties through a graphene interface.