Transition Metal-2D Sulfide Composite Systhesis And Applications In Hydrogen Evaluation And Energy Storage

Nowadays,the energy crisis and environmental problems are increasingly severe,and it's urgent to find a renewable clean energy source.With its high energy density and environmentally friendly advantages,hydrogen is regarded as an ideal energy carrier.One of the scalable and sustainable method,hydrogen evolution reaction,meets the future energy demands.As a promising hydrogen evolution catalysis,MoS₂ has been widely studied,several methods has largely improved its function in acid electrolytes,however,its function in alkaline electrolytes hasn't been effectively promoted yet.In this article,the porous 2D MoS₂ is synthesized by hydrothermal method,then a low-cost simple method for Matel-MoS₂nanocomposites fabrication is provided.A variety of transition metal nanoparticles were successfully synthesized on the surface of MoS₂,and catalytic efficiency in alkaline solution was largely optimized.Then this method is extended to VS₂,which improves the catalysis of VS₂.At the same time,the application of VS₂ in supercapacitor and lithium ion battery is studied,which makes up for the blank of VS₂ research field.The main findings are as follows:?1?Using molybdenum trioxide and thioacetamide as precursors,carbon cloth as carrier,we synthesized porous MoS₂ nanosheets with an average thickness of less than 5 nm by hydrothermal method,then a optimized galvanic processes is utilized to fabric transition metal-MoS₂composites,the catalytic efficiency of MoS₂ in an alkaline solution is largely improved.Taking Co-MoS₂ as working electrode in 1 M KOH,the?₁₀ is only 186 mV,and the Tafel slope is 81 mV dec^-1,which is much better than the catalytic performance of pure MoS₂,meanwhile it shows good stability.Then,the mechanism of the synergistic effect between transition metal and MoS₂ was studied,it was found that the improvement of catalytic performance was derived from the effect of metal nanoparticles on water splitting.At the same time,the composite also showed better OER performance.The?₁₀ of Co-MoS₂ decreased from 460 mV to 360 mV.This study further explored the performance of Co-MoS₂ in whole water splitting reaction.?2?Inspired by the synergistic effect of transition metal-MoS₂,this study further synthesized transition metal-VS₂ composites.Theoretical calculations indicate that VS₂ has excellent HER catalytic performance and conducts.In this study,the VS₂ nanoflowers with good crystallinity were synthesized by adjusting the precursor ratio and reaction temperature.The thickness of the VS₂ nanoflowers was only 20 nm,and then the transition metal-VS₂ was synthesized by a galvanic processes.The electrochemical results show that the composites have better HER catalytic performance.In0.5 M H₂SO₄,the?₁₀ of Co-VS₂ is reduced from 325 mV to 184 mV.?3?Since the large layer space of VS₂ facilitates the embedding of alkali metal ions,this study further explored its application in supercapacitors and lithium ion batteries.In 2 M KCl,at a charge-discharge rate of 0.5 A g^-1,the specific capacity was 1.55 F cm^-2,and at a rate of 4 A g^-1,the specific capacity of the material remains 1.38 F cm^-2.VS₂ was used as the negative electrode of lithium ion battery,and the capacity still remains 210 mAh g^-1after being stabilized several times at a rate of 0.1 A g^-1.In this study,the phase and morphology of VS₂ after lithium intercalation were analyzed,and it was confirmed that this electrochemical lithium intercalation method is a way to reduce the size of two-dimensional materials to obtain corresponding quantum dots.In this study,the transition metal-2D sulfide was synthesized by a convenient galvanic processes,which improved the performance of two-dimensional materials in catalyzing HER and OER,this study further explored its applications in supercapacitor and lithium ion battery.It provides new ideas for the synthesis of nanomaterial composites and their applications in the energy field.