Surface extension of MeS2 (Me=Mo or W) nanosheets by embedding MeSx for hydrogen evolution reaction

Abstract Two-dimensional transition metal dichalcogenides (2D-TMDs), such as MoS 2 and WS 2 nanosheets (MeS 2 -NS), are reported as efficient catalysts for hydrogen evolution reaction (HER), which can potentially replace the expensive platinum catalyst. In this report, 1T phase MeS 2 (1T-MeS 2 ) NS are synthesized by lithium-intercalation exfoliation method, subsequently being modified by amorphous MoS x and WS x (MeS x @MeS 2 -NS) through a solvothermal method. Interestingly, MeS x @MeS 2 -NS significantly improves the HER performance compared with bare MeS 2 -NS as catalysts. Among these, MoS x @MoS 2 is observed to be the best combination for HER, with an onset potential and Tafel slope of 114 mV and 45.1 mV decade −1 , respectively. The enhancement in the HER device using MeS x @MeS 2 -NS as the catalyst originates from vertically grown MeS x , which provides additional active sulfur sites for the reaction, while inhibiting the restacking of MeS 2 -NS. Furthermore, MoS x @MoS 2 -NS shows stable catalytic properties for HER after the 1000 cyclic test, without any observable changes. Thus, this study presents a facile method for the synthesis of 2D-TMD catalyst for HER towards large-scale and long-term stability for practical application.