  For two-dimensional superconductors, the high stability in ambient conditions
is critical for experiments and applications. Few-layer antimonene can be
non-degradative over a couple of months, which is superior to the akin black
phosphorus. Based on the anisotropic Migdal-Eliashberg theory and
maximally-localised Wannier functions, this work predicts that electron-doping
and Ca-intercalation can transform $\beta$-Sb bilayer from a semimetal to a
superconductor. However, the stability of antimonene bilayer in air trends to
be decreased due to the electron doping. To overcome this drawback, two kinds
of protective layers (graphene and $h$-BN) are proposed to enhance the
stability. Interestingly, the superconducting transition temperature will also
be enhanced to $9.6$ K, making it a promising candidate as nanoscale
superconductor.
