  Recently the kagome compounds have inspired enormous interest and made some
great progress such as in the field of superconductivity and topology. Here we
predict a different kagome magnesium triboride (MgB3) superconductor with a
calculated Tc ~12.2 K and Tc ~15.4 K by external stress, the potentially
highest among the reported diverse kagome-type superconductors. We reveal its
various exotic physical properties including the van Hove singularity,
flat-band, multiple Dirac points, and nontrivial topology. The system can be
described by a two-band model with highly anisotropic superconducting gaps on
Fermi surfaces. Its topological and nodal superconducting nature is unveiled by
a recently developed symmetry indicators method. Our results suggest that MgB3
can be a new platform to study exotic physics in the kagome structure, and pave
a way to seek for more superconductors and topological materials with XY3-type
kagome lattice.
