First-Principles Study of Metal–Biphenylene Nanoscale Interfaces: Structural, Electronic, and Catalytic Properties

Understanding how two-dimensional (2D) carbon allotropes interact with metal substrates is crucial for advancing their integration into electronic and catalytic devices. Among these materials, biphenylene (BPN) stands out due to its nonbenzenoid topology, intrinsic metallicity, and high thermal stability, offering unique opportunities beyond graphene. However, the fundamental nature of BPN–metal interfaces, particularly how the substrate influences their structural, electronic, and catalytic properties, remains largely unexplored. In this work, we employ first-principles density functional theory (DFT) calculations to investigate these properties for BPN supported on (111) surfaces of Ag, Au, Ni, Pd, Pt, Cu, Al, and the Cu₃Au alloy. Our results show that the interaction strength between BPN and the substrate governs its stability, corrugation, electronic hybridization, and interfacial charge transfer. In particular, we observe a clear trend where weakly interacting metals preserve the intrinsic features of BPN, while more reactive substrates lead to significant structural and electronic modifications. We further evaluate the hydrogen evolution reaction (HER) activity of these systems, identifying Pd, Pt, Ag, and Cu as promising catalysts. Notably, Ag and Cu offer a favorable combination of catalytic performance, cost, and chemical stability. These findings provide valuable insights into the design of BPN–metal interfaces for future applications in catalysis and nanoelectronics.