2H → 1T phase transition and hydrogen evolution activity of MoS2, MoSe2, WS2 and WSe2 strongly depends on the MX2 composition

We investigate herein the four most widely considered TMD materials: MoS2, MoSe2, WS2 and WSe2. A 2H → 1T phase transition occurs during the chemical exfoliation with different efficiencies among the four materials.