  Superconductivity commonly appears under pressure in charge density wave
(CDW)-bearing transition metal dichalcogenides (TMDs), but has emerged so far
only via either intercalation with electron donors or electrostatic doping in
CDW-free TMDs. Theoretical calculations have predicted that the latter should
be metallized through bandgap closure under pressure, but superconductivity
remained elusive in pristine 2H-MoS2 upon substantial compression, where a
pressure of up to 60 GPa only evidenced the metallic state. Here we report the
emergence of superconductivity in pristine 2H-MoS2 at 90 GPa. The maximum onset
transition temperature Tc(onset) of 11.5 K, the highest value among TMDs and
nearly constant from 120 up to 200 GPa, is well above that obtained by chemical
doping but comparable to that obtained by electrostatic doping. Tc(onset) is
more than an order of magnitude larger than present theoretical expectations,
raising questions on either the current calculation methodologies or the
mechanism of the pressure-induced pairing state. Our findings strongly suggest
further experimental and theoretical efforts directed toward the study of the
pressure-induced superconductivity in all CDW-free TMDs.
