  Here we present the superconducting property and structural stability of
kagome CsV3Sb5 under in-situ high pressures. For the initial SC-I phase, its Tc
is quickly enhanced from 3.5 K to 7.6 K and then totally suppressed at P~10
GPa. Further increasing the applied pressures, an SC-II phase emerges at P~15
GPa and persists up to 100 GPa. The Tc rapidly increases to the maximal value
of 5.2 K at P=53.6 GPa and rather slowly decreases to 4.7 K at P=100 GPa. A
two-dome-like variation of Tc in CsV3Sb5 is concluded here. The Raman
measurements demonstrate that weakening of E2g model and strengthening of A1g
model occur without phase transition as entering the SC-II phase, which is
supported by the results of phonon spectra calculations. Electronic structure
calculations reveal that exertion of pressure may bridge the gap of topological
surface nontrivial states near EF, i. e. Z2 invariant. Meanwhile, it enlarges
Fermi surface significantly, consistent with the increased carrier density. The
findings here point out the change of electronic structure and strengthened
electron-phonon coupling should be responsible for the pressure-induced
reentrant SC.
