Synthesis Of 2D SnS₂ Nanosheets For Energy Storage And Conversion Applications

Layered metal dichalcogenides constructed from 2D covalently-bonded monolayers has the advantages of large specific surface area,wide interlayer spacing,ultra-thin thickness and low cost etc.It has broad prospects in the fields of lithium ion batteries and electrochemical hydrogen evolution.In this thesis,the SnS₂ nanosheets were synthesized and used as a negative electrode material for lithium ion batteries and a high activity catalytic electrode material for hydrogen evolution reaction.The lithium storage performance and hydrogen evolution performance were studied.The main research results are as follows:?1?We report a simple solvothermal preparation of interlayer-expanded SnS₂nanosheets heating treatment in nitrogen,Sn⁴⁺deacidized into Sn²⁺to form S vacancy defects,reducing the band gap.a large number of defects also provide a channel for rapid insertion and extraction of lithium ions,accelerating the rapid transport of ions.orthorhombic SnS annealed at 600?has better Lithium storage performance than the hexagonal SnS₂ as the negative material of Li-ion Battery and the improved charge and discharge capacity and cycle stability.After 500 cycles at a current density of 1 A g^-1,the SnS₂ and SnS sample electrodes had the reversible capacity of 680 and 824 mA h g^-1,with the capacity retention rate of 64.3 and 78.1%,respectively,higher than the theoretical capacity of SnS₂(645 mA h g^-1)and SnS(782 mA h g^-1).At the same time,at the current density of 0.1 A g^-1,SnS₂ and SnS sample electrodes also provided the discharge capacities of 1100 and 1300 mA h g^-1.When the current density returned to0.1 A g^-1,the discharge capacities recovered to 980 and 1080 mA h g^-1,showing excellent rate performance.?2?Interlayer-expanded and defect-rich?IEDR?SnS₂ nanosheets,are synthesized by designing precursors in octylamine solvent method and employed as efficient HER catalysts.Due to the intercalation of the intercalated octylamine molecules,Interlayer spacings of few-layered SnS₂ nanosheets are dramatically expanded to 0.93 nm,which is a 0.34 nm increase relative to those?0.589 nm?of the bulk counterparts,and the volume expanded by 57.9%.On the other hand,During the solvothermal synthesis,the octylamine molecules capped on the surfaces of the SnS₂ nanocrystallites can effectively suppress the orientation growth of the primary SnS₂ nanocrystallites,thus resulting in the formation of disordered basal planes,produced a large number of defects,exposed more active sites.Consequently,interlayer-expanded and defect-rich?IEDR?SnS₂ catalysts exhibit striking activities,delivering a small Tafel slope(65mV dec^-1),a low onset overpotential?97 mV?,large cathodic current densities and excellent long-term stabilities.This work paves a new pathway to improve the electrocatalytic HER activity by defect modulation.