Theoretical Study On The Properties Silicon Supported Sandwich Molecular Wires And MoS₂ Catalytic For Hydrogen Production

Low-dimensional materials have attracted much attention because of their unique physical and chemical properties,which completely different from those of three-dimensional materials due to their limited dimensions.One-dimensional(1D)organometallic complexes formed by transition metal(TM)atoms and organic π-conjugated ligands are promising spintronic materials.During the past few decades,several prototype multidecker metal atom-π sandwich complexes have been synthesized in vacuo by the laser vaporization synthesis methodand and have undergone intensive theoretical studies.However,despite significant experimental and theoretical efforts,the practical applications of these gas-phase molecular nanowires in spin-devices were lagged seriously as the molecules easy to crush.Here in this paper,we proposed a two-step assembly of sandwich transition-metal/organic molecular wires on H-terminated Si(100)-(2×1)surface in density functional theory(DFT).It is unveiled that TM atoms bind asymmetrically to the adjacent organic rings,which leads to novel electronic and magnetic properties in stark contrast to the well-studied gas phase SWMs.Si-[Mn(styrene)]∞,Si-[Mn(styrene)]∞-[Cr(styrene)]∞,Si-[Vinylnaphthalene-Cr2]∞,Si-[Eu-Ch]∞,Si-[Eu-Cnt]∞,Si-[Vinylcyclopentadiene-Ti]∞ and Si-[Vinylferrocene-TM]∞(TM=Sc,V,Cr)are typical half metals in this work.These studies provide new insights into the structure and properties of surface supported 1-D sandwiched molecular wires and may inspire the future experimental synthesis of substrate confined organometallic sandwiched molecular wires.The fast-growing world population requires a huge increase in energy consumption.Hydrogen(H2),which has the highest energy density of all chemical fuels(142 MJ kg-1),is considered as the most promising energy carrier for the future.Two-dimensional(2D)transition-metal-dichalcogenide(TMD)nanosheets have long reached a crescendo in the realms of electrochemical applications initiated by their remarkable catalytic and electronic properties.However,the fundamental mechanism about the catalytic activity of 1T-MoS2 and the associated phase evolution remain elusive and controversial.Here in the seventh part of this paper,we reveal the fact that 1T phase can be irreversibly transformed into amore active 1T’ phase as true active sites in photocatalytic HERs,resulting in a "catalytic site self-optimization".In spite constructed heterojunction solved the charge recombination in the TMDs perfectly,the charge transfer between materials and stability of heterojunction are still very challengeable,owing to the fact that the heterojunction which contained 2D materials bound together by weak van der Waals interactions.In the eighth part of this paper,we propose a kind of anionic exchange to make surface abundant defects make a strong chemical coupling between TMDs with CdS.The influence of anion exchange on the interface of heterojunction is also discussed theoretically in this paper.