Semiconducting Pt Structures Stabilized on 2D MoS 2 Crystals Enable Ultrafast Hydrogen Evolution

Abstract Metallic platinum is the best and most widely investigated catalyst for hydrogen evolution, yet little is known about Pt in its semiconducting form. Here, it is shown that semiconducting Pt structures with a thickness of only two atomic layers (0.4 nm) can be stabilized on 2D MoS 2 crystals. Reducing the thickness of Pt particles below the Fermi wavelength (0.5 nm) opens a sizeable (0.3–0.4 eV) gap in their electronic structure. The resulting electronic structure is qualitatively different from both the metallic bands of larger Pt nanoparticles and the atomic orbitals of Pt single atom catalysts while displaying the highest intrinsic activity among them. Semiconducting Pt bilayers enable H 2 production at ten times higher rates (≈1400 H 2 s −1 @ η = 100 mV) than Pt single atom catalysts, and match the activity of commercial Pt nanoparticles (Pt /C catalysts) at three orders of magnitude lower Pt loadings.