Synthesis And Catalytic Hydrogen Evolution Properties Of MoS₂-based Composite Electrocatalysts

The exploration of cheap and high-performance electro-catalysts is the key to developing clean hydrogen energy.Molybdenum disulfide（MoS₂）is a good candidate to replace the noble Pt-based electrocatalysts for the hydrogen evolution reaction（HER）,because of its lamellar structure similar to graphene and good catalytic activity for HER.Herein,three MoS₂-based electrocatalysts have been synthesized by the hydrothermal method,and the internal mechanism of improving their hydrogen evolution performance was explored through the detection of their composition,structure,and HER performance.The main research contents are summarized as follows:（1）By introducing FeS₂,we synthesized FeS₂@MoS₂ electrocatalyst with flower-like structures.The introduction of FeS₂ prevents the agglomeration of MoS₂.Moreover,due to the construction of FeS₂@MoS₂heterostructure,the obtained FeS₂@MoS₂ electrocatalyst has more exposed edge active sites,faster electron transfer efficiency,and optimized free energy of hydrogen adsorption,which shows better catalytic performance for HER.In the 0.5 M H₂SO₄ electrolyte,the synthesized FeS₂@MoS₂ possesses good activity and stability for HER,and the overpotential at a current density of-10 m A cm^-2 is-231 m V with a small Tafel slope of 58 m V dec^-1.（2）Two-step hydrothermal method was used to prepare the CoS₂@MoS₂ electrocatalyst.The experimental results reveal that there is a strong electron interaction and heterogeneous interface between CoS₂ and MoS₂,thus leading to smaller electrochemical impedance and better mass transportation ability.Moreover,the electron transfer on the heterogeneous interface and the interaction between CoS₂ and MoS₂ make the formation of the electrophilic and nucleophilic region.The negative O and positive H are adsorbed by the electrophilic CoS₂ and nucleophilic MoS₂,respectively,which promotes the cleavage of O-H bonds in the polar water molecules.Hence,CoS₂@MoS₂ displays better hydrogen evolution performance in 1M KOH with a small₁₀ of-232 m V and Tafel slope of 89 m V dec^-1.（3）The Cu S@MoS₂ electrocatalyst with nanoflower structure was obtained by a hydrothermal method,which has more catalytic active sites and larger electrochemically active surface area.Benefiting from the synergistic effect between MoS₂ and Cu S,the Cu S@MoS₂ has the best HER performance compared with single Cu S and MoS₂.In 0.5 M H₂SO₄,the₁₀ of Cu S@MoS₂ electrocatalyst is-293 m V with a small Tafel slope of 60 m V dec^-1.Three MoS₂-based composite electrocatalysts were synthesized by heterostructure engineering.Wherein FeS₂@MoS₂ and Cu S@MoS₂ have high catalytic activity in 0.5 M H₂SO₄,and CoS₂@MoS₂ shows good hydrogen evolution performance in 1 M KOH.Therefore,this paper could provide some ideas for the construction and performance regulation of the MoS₂-based composite catalyst in the future.Attached with 53 figures,6 tables,and 101 references.