Ripples in Two-Dimensional Supports Direct Charge–Curvature Coupling in Donor–Acceptor Interfacial Chemistry

Ripples, wrinkles, and bubbles are common out-of-plane distortion motifs in deformable two-dimensional (2D) materials. By reshaping electronic structure, these distortions introduce a design dimension for functional materials under external bias. Here, we establish the relationship between out-of-plane-distortion-induced curvature and external-bias-induced charge and show that variable curvature can generate chemically distinct donor–acceptor interfacial chemistry on a single surface. Using corrugated graphene-supported M–N4 single-atom sites, representative of transition-metal–nitrogen–carbon (M–N–C) materials used in heterogeneous and electrochemical catalysis, we examine how negative curvature (mountain) and positive curvature (valley) regions respond to electron- and hole-rich conditions relevant to external bias. We identify a metal-dependent charge–curvature relationship in which donor and acceptor binding exhibit complementary mountain–valley asymmetry, arising from the interplay between localized and delocalized electronic states. The same asymmetry extends to coadsorption, where donor and acceptor species preferentially occupy complementary curvature regions of the shared corrugated support, resulting in long-range charge redistribution across the coupled donor–support–acceptor interface. Overall, these results establish ripples as chemically active motifs for bias-controlled interfacial chemistry relevant to catalysis and optoelectronics.