▎ 摘　　要

NOVELTY - Synthesizing self-assembled mixed-dimensional heterostructure involves depositing boron on substrate to grow borophene on it at a substrate temperature in an ultrahigh vacuum (UHV) chamber, depositing orderly 4,4"-dibromo-p-terphenyl (DBTP) on the borophene grown substrate at room temperature in the UHV chamber to form a composite structure, and controlling multi-step on-surface coupling reactions of the composite structure to self-assemble a borophene/graphene nanoribbon mixed-dimensional heterostructure. USE - Method for synthesizing self-assembled mixed-dimensional heterostructure used in composition (claimed). ADVANTAGE - The borophene exhibits a high propensity for polymorphism, and has attracted intense research interest as an emerging synthetic two-dimensional (2D) material with unique structural characteristics and distinctive electronic properties including anisotropic metallicity, charge density wave phenomena, and predicted high-temperature superconductivity. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: 1. a self-assembled mixed-dimensional heterostructure synthesized by synthesis method; and 2. a composition, which comprises: a self-assembled mixed-dimensional heterostructure comprising two-dimensional (2D) metallic borophene and one-dimensional (1D) semiconducting armchair-oriented graphene nanoribbons (aGNRs).