The paper reports the first experimental realization of two-dimensional (2D) boron sheets on an Ag(111) substrate. The researchers identified two distinct boron sheet structures, corresponding to a triangular boron lattice with different arrangements of hexagonal holes. These structures, labeled as S1 and S2, were observed to be relatively stable against oxidation and interact weakly with the substrate. The S1 phase is characterized by a 212-sheet structure, which aligns well with theoretical models, while the S2 phase likely corresponds to a ζ3-sheet model. First-principles calculations confirmed the validity of these structures and explained their formation through commensuration with the Ag(111) substrate. The 2D boron sheets exhibit metallic properties, as evidenced by scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. The weak interaction between the boron sheets and the Ag(111) substrate suggests the potential for freestanding 2D boron sheets, which could be useful for future electronic applications. The study opens new avenues for exploring boron-based microelectronic devices and highlights the complementary chemical properties of boron compared to carbon.The paper reports the first experimental realization of two-dimensional (2D) boron sheets on an Ag(111) substrate. The researchers identified two distinct boron sheet structures, corresponding to a triangular boron lattice with different arrangements of hexagonal holes. These structures, labeled as S1 and S2, were observed to be relatively stable against oxidation and interact weakly with the substrate. The S1 phase is characterized by a 212-sheet structure, which aligns well with theoretical models, while the S2 phase likely corresponds to a ζ3-sheet model. First-principles calculations confirmed the validity of these structures and explained their formation through commensuration with the Ag(111) substrate. The 2D boron sheets exhibit metallic properties, as evidenced by scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. The weak interaction between the boron sheets and the Ag(111) substrate suggests the potential for freestanding 2D boron sheets, which could be useful for future electronic applications. The study opens new avenues for exploring boron-based microelectronic devices and highlights the complementary chemical properties of boron compared to carbon.