Alkali metal doped MoS2 nanosheets for electrocatalytic hydrogen evolution reaction

Salt-assisted in situ synthesis strategy enables alkali metal doping and S vacancies in MoS 2 , yielding MoS 2 nanosheet HER catalysts. • The Li-MoS 2 achieves a low overpotential of 185 mV at 10 mA cm⁻ 2 , with a Tafel slope of 108 mV dec⁻ 1 , and long-term stability. • Alkali metal doping induces S vacancies and negative Mo 3 d shifts, boosting Mo surface electron density, H desorption, and HER activity. Designing highly active and stable two-dimensional transition metal disulfides electrocatalysts that can outperform Pt remains challenging due to the inert basal plane and poor electrical conductivity of pristine materials. Herein, we report a salt-assisted in situ synthesis that simultaneously achieves alkali metal doped (Li, Na, K) and high-density S vacancies during MoS 2 growth, thereby avoiding the lattice damage inherent to conventional post-treatment methods. Electrochemical measurements reveal that Li-doped MoS 2 (Li-MoS 2 ) exhibits markedly enhanced HER activity in acidic media, requiring an overpotential of only 185 mV to at a current density of 10 mA cm −2 , along with a Tafel slope of 108 mV dec −1 . Outperforming both pristine MoS 2 and Na-/K-doped counterparts under the same conditions, it also maintains excellent stability over 50 h. This work provides an economical, sustainable, and efficient synthetic route for defect engineering in two-dimensional catalysts. Download: Download high-res image (185KB) Download: Download full-size image