Activating a Two-Dimensional PtSe₂ Basal Plane for the Hydrogen Evolution Reaction through the Simultaneous Generation of Atomic Vacancies and Pt Clusters

Two-dimensional (2D) PtSe₂ has emerged as a promising ultrathin electrocatalyst due to its excellent catalytic activity and conductivity. However, the PtSe₂ basal plane is inert for the hydrogen evolution reaction (HER), which greatly limits its electrocatalytic performance. Here, in light of theoretical calculations, we designed a facile approach for activating the 2D PtSe₂ basal plane for the HER by simultaneously introducing atomic vacancies of Se, Pt, and Pt clusters through a mild Ar plasma treatment. We tracked changes in the structures and catalytic performance of PtSe₂ by combining microscopic imaging, spectroscopic mapping, and electrochemical measurements in microcells. The highest performance of the activated PtSe₂ basal plane that we obtained was superior to those of other 2D transition metal dichalcogenide-based electrocatalysts measured in microcells in terms of the overpotential, the Tafel slope, and the exchange current density. This study demonstrates the great potential of activated 2D PtSe₂ as an ultrathin catalyst for the HER and provides new insights on the rational design of 2D electrocatalysts.