Study On The Design,Fabraction And Properties Of MXene/MoS₂ Nanocomposites

Two-dimensional(2D)materials,such as graphene,boron nitride,black phosphorus,two-dimensional transition metal carbonitrides(MXene),and transition metal sulfides(TMDs),etc.,have attracted many attentions from researchers due to their unique physical and chemical properties.MXene is a new class of potential materials for applications of electrnic,energy and environmental technologies.This paper focused on the preparation and performance of MXene/MoS₂ nanocomposites.Both experimental and theoretical studies explored the performance of MXene and MXene/MoS₂ nanocomposites for photocatalytic degradation of organic pollution,electrochemical hydrogen evolution(HER)and supercapacitors.The density functional theory(DFT)calculations were also performed to study the application of MXene/MoS₂ for the overall water splitting.First,we prepared Ti₃C₂/MoS₂ composites by in-situ hydrothermal method.We studied the performance of Ti₃C₂/MoS₂ composites to degrade Rhodamine B under visible light irradiation and its application in electrochemical hydrogen evolution.The results show that the photogenerated electrons in MoS₂ layer of the composite are transferred to Ti₃C₂ layer under the affect of the built-in electric field,which suppressed the recombination of the electron-hole pairs,thereby improving the photocatalytic degradation efficiency.The enhanced electrocatalytic activity of Ti₃C₂/MoS₂ nano-composites can be attributed to the imporved electron migreation promioted by the high electrical conductivity of Ti₃C₂ and more active sites in Ti₃C₂/MoS₂ nano-composites.Second,we carried out a systematic investigation on the geometry structures,electronic properties,optical properties and carrier mobilities of the M₂CO₂-II(M=Ti,Zr and Hf)and MoS₂ heterostructures with a hybridized density functional theory(DFT).The B'C'stacked M₂CO₂-II/MoS₂ heterostructure with a short interlayer distance is energetically favorable.All M₂CO₂-II/MoS₂ bilayer and sandwich-like structures are indirect semiconductors.The maximum of valence band(VBM)and conduction band minimum(CBM)of M₂CO₂-II/MoS₂ heterostructures are dominated by different layers,implying the spatial separation of photogenerated electron-hole pairs.Three M₂CO₂-II/MoS₂heterostructures,including Zr₂CO₂-II/MoS₂-S-B'C',Hf₂CO₂-II/MoS₂-B-B'C',and Hf₂CO₂-II/MoS₂-S-B'C',are considered as the promising candidates for overall water splitting due to their appropriate band structures,suppressed recombination of photogenerated electron-hole pairs,enhanced optical absorption and carrier mobilities.In addition,the gaint hole mobility makes Ti₂CO₂-II/MoS₂ heterostructure a potential candidate for the application of 2D electronic devices.Finally,MXene has a high surface energy and is easily oxidized to prepare transition metal oxides.Transition metal oxides with fast ion diffusion and good cycle stability are usually considered as the super-capacitor materials.2D V₂C was prepared by a chemical etching method.The V₂O₅/C/V₂C composites were then prepared by rapidly oxidizing V₂C material in air.The results of XRD,BET and electrochemical measurements show that the electrochemical performance of V₂O₅/C/V₂C composite is greatly improved due to the increased interface contact area and tight connection between V₂O₅ with conductive carbon.