Tunable active edge sites in PtSe2 films towards hydrogen evolution reaction

Layered transition-metal dichalcogenides (TMDCs) have received great interest due to their potential applications in many fields including electronics, optoelectronics, electrochemical hydrogen production and so on. Recent research effort on the development of effective hydrogen evolution reaction (HER) is to modulate the active edge sites through controlling surface structure at the atomic scale. Here we firstly demonstrate a facile strategy to synthesize large-area and edge-rich platinum diselenide (PtSe2) via selenization of Pt films by magnetron sputtering physical deposition method. The edge site density of the PtSe2 can be effectively controlled by tuning the thickness of Pt films. The HER activity of the PtSe2 can be enhanced significantly as the active edge site density increases. The maximum cathodic current density of 227 mA/cm2 can be obtained through increasing the edge density, which well agrees with the density functional theory calculations. Our work provides a fundamental insight on the effect of active edge site density towards HER.