Boosting Hydrogen Evolution Performance of MoS_2 by Band Structure Engineering

摘要

Molybdenum sulfide (MoS_2) has emerged as a promising electrocatalyst for hydrogen evolution reaction (HER) owing to its high activity and stability during the reaction. However, the efficiency of hydrogen production is limited by the number of active sites in MoS_2. In this work, a simple method of fabricating polycrystalline multilayer MoS_2 on Mo foil for efficient hydrogen evolution is demonstrated by controlling the sulfur (S) vacancy concentration, which can introduce new bands and lower the hydrogen adsorption free energy (ΔG_H). For the first time, theoretical and experimental results show that the HER performance of synthesized MoS_2 with S vacancy can be further enhanced by the very small amount of platinum (Pt) decoration, which can introduce new gap states and more catalytic sites in real space with suitable free energy. The fabricated hybrid electrocatalyst exhibits significantly smaller Tafel slope of 38 mV dec~(-1) and better HER electrocatalytic activity compared to previous works. This approach provides a simple pathway to design lowcost, efficient and sizable hydrogen-evolving electrode by simultaneously tuning the MoS_2 band structure and active sites.