The
possible structures of borophene have attracted great research
interests during the past years due to the multicenter bonding characteristics
derived from the electron deficiency of elemental boron. Particularly,
the diverse structural architectures of borophene obtained in the
experiment reveal the substrate-modulation characteristic, yet not
fully explored. Herein, the global structures of borophene interfacially
confined on Al(111), Ag(111), and Au(111) substrates are identified
through the structure-search method based on particle swarm optimization
and first-principles calculations. It unveils first the evolvement
from monolayer to bilayer or cluster borophene with elevated boron
density. Two energetically preferential bilayer structures, i.e., δ3β12 and BL-α5, are confirmed on Al and Ag, and a peculiar cluster layer,
IH-BS, is observed on Au, originated from the differences in electronegativities
(Au > B > Ag > Al). Notably, both the BL-α5 and IH-BS
are semiconducting with band gaps of 1.141 and 1.136 eV, and δ3β12 is metallic. This work demonstrates the
substrate-modulated borophene structures with potential applications
in nanoelectronics.