Absence of topological beta-antimonene and growth of alpha-antimonene on noble metal Ag(111) and Cu(111) surfaces

Antimonene is a promising two-dimensional material predicted to host intriguing properties. Recent works have claimed the successful preparation of beta-antimonene on noble metal surfaces, including Ag(111) and Cu(111). However, as scanning tunneling microscopy gives only the topographic information, the possibility of surface alloying for the claimed beta-antimonene remains elusive. In this work, by scanning tunneling spectroscopy and in situ Raman spectroscopy measurements, we provide compelling evidence that the "beta-antimonenes" on Ag(111) and Cu(111) reported in previous studies are both surface alloys, namely, Ag2Sb and Cu2Sb. Thus, beta-antimonene does not exist on these substrates. Instead, we find that alpha-antimonene can be grown on both alloy surfaces, with different substrate-induced strain modulation effects. Our work not only clarifies the growth dynamics of Sb on Ag(111) and Cu(111) but also provides two model systems to realize alpha-antimonene with tunable strains.