Oxygen-incorporated MoX (X: S, Se or P) nanosheets via universal and controlled electrochemical anodic activation for enhanced hydrogen evolution activity

Molybdenum disulphide (MoS₂) presents a promising electrocatalyst for hydrogen evolution reaction (HER). Immense effort has been made to optimize MoS₂ catalysts with more active sites for the sake of satisfying HER performance. In this work, the MoS₂ is modulated by electrochemical anodic activation at positive potentials in acidic media to fast intercalate oxygen into MoS₂ in 200 s, leading to the dramatic enhancement for HER activity. Cyclic voltammetry, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, in situ atomic force microscope and operando Raman spectroscopy are applied to explore the oxygen doping process of MoS₂ in 0.5 M H₂SO₄ electrolyte. In brief, the optimal oxygen doped MoS₂ catalyst exhibits an onset potential of as low as −87 mV vs. RHE at 1 mA cm⁻² accompanied by excellent stability, which is reduced about 50 mV compared to that before electrochemical anodic activation of MoS₂ (135 mV). This work will create a simple and universal method to improve the activities of catalysts by electrochemical anodic activation process, which was successfully applied to MoS₂, MoSe₂ and MoP.