Directly deposited porous two-dimensional MoS2 films as electrocatalysts for hydrogen evolution reactions

Two-dimensional (2D) MoS2 has recently emerged as an efficient hydrogen evolution reaction (HER) catalyst due to its unique atomic layered structure and stability in harsh acidic environment. However, the high electrochemical performance of MoS2 is still limited to edges of its 2D layers. Here, we report the synthesis of highly porous MoS2 films exhibiting a large density of edge sites by using a direct sputter deposition method. Interestingly, the as-deposited MoS2 films resulted into a 3R phase with nano porous structure which is attributed to the lattice relaxation and high energy of sputtered ions. The as-synthesized porous MoS2 nanostructures demonstrate an excellent electrocatalytic performance with a low HER onset potential of ∼0.2 V, long-term cycling stability, and a low Tafel slope in the range of ∼80-90 mV/decade at a high cathodic current density.