Preparation Of MoS₂ Based Materials And Their Application In Hydrogen Evolution Reaction

Nowadays,air pollution is deteriorating in many places around the world.Developing clean and affordable energy is in urgent need.Hydrogen?H₂?,one of the clean and renewable sources of energy,is gradually becoming a satisfactory substitute for fossil fuels due to its high energy density and environmental friendliness.Electrocatalysis plays an important part in the clean energy transformation,which is of great significance to sustainable development.Water splitting catalyzed by hydrogen production catalysts has been testified to be the highest efficient and environmental-friendly hydrogen evolution technique.Platinum?Pt?and Pt-based materials play a vital role in the hydrogen evolution reaction?HER?for their excellent electrocatalytic property in an acidic medium.However,the high cost and rarity limit their widespread use.MoS₂,one of the most interesting layered materials with the merits of being inexpensive and earth-abundant,is believed to be active for HER and has attracted great attention to be a prospective Pt alternative.Three commonly found polymorphs are defined as 1T,2H,and 3R,where the digits represent the layer numbers of the crystallographic unit cells.The letters designate the type of symmetry,T stands for tetragonal(D_3d group),H represents hexagonal(D_3h group),and R denotes rhombohedral(C⁵_3v group).Moreover,1T-MoS₂is a metastable metallic phase,whereas 2H-MoS₂ and 3R-MoS₂ are a semiconducting,thermodynamically stable phase.Various theoretical and experimental studies have been proved the relationship between MoS₂ nanostructures and its catalytic performance,revealing that HER activity was related to the density of S-edge-sites.We have synthesized MoS₂-Co nanoboxes,MoS₂/Co@MWCNTs,MoS₂-NiNi PBA nanopaltes and WS₂-NiNi PBA nanopaltes by a facile hydrothermal method.For the characterization,scanning electron microscope?SEM?,transmission electron microscopy?TEM?,X-ray photoelectron spectroscopy?XPS?and Raman spectra were used to confirm the structure of MoS₂-based materials.As novel nanostructured electrocatalysts for HER,MoS₂-Co nanoboxes,MoS₂/Co@MWCNTs,MoS₂-NiNi PBA nanopaltes and WS₂-NiNi PBA nanopaltes exhibit favorable electrochemica activity.Part 1:Cobalt Incorporated MoS2 Hollow Structure with Rich Out-of-plane Edges for Efficient Hydrogen Production.We have successfully synthesized MoS₂-Co nanoboxes by a facile hydrothermal method.We report the method of synthesizing novel Co PBA nanocubes at different aging times,and the synthesis of the MoS₂-Co nanoboxes through the reaction between Co PBA nanocubes and ammonium thiomolybdate??NH₄?₂MoS₄?under a hydrothermal condition at different reaction times.For discussing the relationship between structural change of MoS₂ and HER catalytic performance,we utilized the Raman spectroscopy for monitoring the changes of MoS₂structure.With 18 h aging time and 12 h reaction time,MoS₂-Co nanoboxes through the reaction between Co PBA nanocubes and?NH₄?₂MoS₄ under hydrothermal condition,the structure exposes maximum S-edge-sites.As a novel nanostructured electrocatalyst for HER,MoS₂-Co nanoboxes exhibit favorable electrochemical activity.Part 2:Three-Dimensional HierarchicalMoS2/Co@MWCNTs as an Electrocatalyst for Hydrogen Evolution Reaction.The Co nanoparticles?Co NPs?have loaded on the surface of multi-walled carbon nanotubes?MWCNTs?,and then MoS₂ have growth on the surface of MWCNTs by a facile hydrothermal method.It was found that the participation of MWCNTs and Co NPs not only improved the electrical conductivity of the catalyst,but also further exposes maximum S-edge-site.The MoS₂/Co@MWCNTs shown a highly active and long durable catalyst in HER.Part 3:Nanodots of Transition Metal?M,W?Disulfides Grown on NiNi PBA Nanopaltes as an Electrocatalyst for Efficient Hydrogen Evolution.We have synthesized MoS₂-NiNi PBA nanopaltes and WS₂-NiNi PBA nanopaltes by a facile hydrothermal method.For the characterization,SEM,TEM and XPS were used to confirm the structure of MoS₂-NiNi PBA nanopaltes and WS₂-NiNi PBA nanopaltes.TEM shows that the size of MoS₂ nanodots and WS₂ nanodots were 1.80 and 1.48 nm,respectively.As a novel nanostructured electrocatalyst for HER,MoS₂-NiNi PBA nanopaltes and WS₂-NiNi PBA nanopaltes exhibit excellent electrochemical activity.