Enhancing Hydrogen Evolution Activity of Monolayer\nMolybdenum Disulfide via a Molecular Proton Mediator

Abstract

The\nconfiguration and local environment of active sites in transition\nmetal dichalcogenides can significantly alter their electrocatalytic\nactivity toward the hydrogen evolution reaction (HER). Herein, we\ndemonstrate that the HER activity of monolayer MoS₂ electrocatalysts\ncan be enhanced through the modulation of active sites by introducing\na molecular mediator that alters the coverage of adsorbed protons.\nSodium dodecyl sulfate (SDS) promotes the intrinsic HER activity of\nboth terrace-based sulfur vacancies (V_S) and edge sites\nduring HER operation in an acidic environment, leading to increases\nin the turnover frequency (TOF) of both sites by up to 5 orders of\nmagnitude. Simulations indicate that SDS facilitates proton adsorption\nby catching protons from hydronium ions and releasing them to V_S, which reduces the energy barrier by creating a stair-case-like\nfree energy profile. Our results highlight the ability to tailor the\nactivity of electrocatalysts by synergistically combining proton transfer\nmediators with engineered active sites.