Synergistic Regulation of S-Vacancy of MoS(2)-Based Materials for Highly Efficient Electrocatalytic Hydrogen Evolution

Low or excessively high concentration of S-vacancy (C (S-vacancy)) is disadvantageous for the hydrogen evolution reaction (HER) activity of MoS(2)-based materials. Additionally, alkaline water electrolysis is most likely to be utilized in the industry. Consequently, it is of great importance for fine-tuning C (S-vacancy) to significantly improve alkaline hydrogen evolution. Herein, we have developed a one-step Ru doping coupled to compositing with CoS(2) strategy to precisely regulate C (S-vacancy) of MoS(2)-based materials for highly efficient HER. In our strategy, Ru doping favors the heterogeneous nucleation and growth of CoS(2), which leads to a high crystallinity of Ru-doped CoS(2) (Ru-CoS(2)) and rich heterogeneous interfaces between Ru-CoS(2) and Ru-doped MoS(2-x) (Ru-MoS(2-x)). This facilitates the electron transfer from Ru-CoS(2) to Ru-MoS(2-x), thereby increasing C (S-vacancy) of MoS(2)-based materials. Additionally, the electron injection effect increases gradually with an increase in the mass of Co precursor (m (Co)), which implies more S(2-) leaching from MoS(2) at higher m (Co). Subsequently, C (S-vacancy) of the as-synthesized samples is precisely regulated by the synergistic engineering of Ru doping and compositing with CoS(2). At C (S-vacancy) = 17.1%, a balance between the intrinsic activity and the number of exposed Mo atoms (EMAs) to boost highly active EMAs should be realized. Therefore, the typical samples demonstrate excellent alkaline HER activity, such as a low overpotential of 170 mV at 100 mA cm(−2) and a TOF of 4.29 s(−1) at -0.2 V. Our results show promise for important applications in the fields of electrocatalysis or energy conversion.