Enhanced HER Efficiency of Monolayer MoS 2 via S Vacancies and Nano-Cones Array Induced Strain Engineering.

Molybdenum disulfide (MoS 2 ) has gained significant attention as a promising catalyst for hydrogen evolution reaction (HER). The catalytic performance of MoS 2 can be enhanced by either altering its structure or regulating external conditions. In this study, a novel approach combining the introduction of sulfur vacancy (V S ) and biaxial tensile strain to create more active sites and modulate the band structure of monolayer MoS 2 is proposed. To achieve the desired strain level, nano-cones (NCs) array substrates facilely fabricated by dip-pen nanolithography (DPN) are employed. The magnitude of the applied tensile strain can be finely tuned via adjusting the height of the NCs. Furthermore, on-chip electrochemical devices are constructed based on artificial structures, enabling precise optimization of HER performance of MoS 2 through the synergistic effect of V S and strain. Combined with the d-band theory, it reveals that the HER properties of V S -MoS 2 are highly dependent on the degree of tensile strain. This study presents a promising avenue for the design and preparation of high-performance 2D catalysts for energy conversion and storage applications.