Structural and electronic properties of transition-metal chalcogenides Mo5S4 nanowires

Transition-metal chalcogenide nanowires(TMCN) as a viable candidate for nanoscale applications have been attracting much attention for the last few decades. Starting from the rigid building block of M6 octahedra(M = transition metal),depending on the way of connection between M6 and decoration by chalcogenide atoms, multiple types of extended TMCN nanowires can be constructed based on some basic rules of backbone construction proposed here. Note that the well-known Chevrel-phase based M6X6 and M6X9(X = chalcogenide atom) nanowires, which are among our proposed structures, have been successfully synthesized by experiment and well studied. More interestingly, based on the construction principles, we predict three new structural phases(the cap, edge, and C&E phases) of Mo5S4, one of which(the edge phase) has been obtained by top-down electron beam lithography on two-dimensional MoS2, and the C&E phase is yet to be synthesized but appears more stable than the edge phase. The stability of the new phases of Mo5S4 is further substantiated by crystal orbital overlapping population(COOP), phonon dispersion relation, and thermodynamic calculation. The barrier of the structural transition between different phases of Mo5S4 shows that it is very likely to realize an conversion from the experimentally achieved structure to the most stable C&E phase. The calculated electronic structure shows an interesting band nesting between valence and conduction bands of the C&E Mo5S4 phase, suggesting that such a nanowire structure can be well suitable for optoelectronic sensor applications.

Synthesis,Characterizations and Applications of Cadmium Chalcogenide Nanowires:A Review

Cadmium chalcogenide nanowires have demonstrated superior electrical and optical properties,and have emerged as prominent building blocks for nanoscale electronic and optoelectronic devices.In addition to the effort devoted to advance techniques of fabricating high quality nanowires,much has been endeavored to elucidate their unique physical properties for better design and development of functional devices with low power consumption and high performance.Herein,this article provides a comprehensive review of the forefront research on cadmium chalcogenide nanowires,ranging from material synthesis,property characterizations,and device applications.

镉的硫族化合物半导体纳米线阵列的模板法合成及其紫外可见吸收光谱研究(英文)

以多孔氧化铝为模板 ,用交流电分别通过含有相应的CdCl2 、ZnCl2 、单质S、Se等的二甲亚砜 (DMSO)溶液 ,沉积CdS、CdSe以及CdxZn1-xS半导体纳米线阵列并研究其紫外可见吸收光谱 .实验结果表明 ,当半导体纳米线的直径小于 2 5nm时 ,其吸收边相对于体相的吸收边产生蓝移 ,而且蓝移的幅度随着半导体纳米线直径的减小而增加 ,显示了明显的量子限域效应 .

Thermoelectric Properties of p-Type PbSe Nanowires

The thermoelectric properties of individual solution-phase synthesized p-type PbSe nanowires have been examined.The nanowires showed near degenerately doped charge carrier concentrations.Compared to the bulk,the PbSe nanowires exhibited a similar Seebeck coefficient and a significant reduction in thermal conductivity in the temperature range 20 K to 300 K.Thermal annealing of the PbSe nanowires allowed their thermoelectric properties to be controllably tuned by increasing their carrier concentration or hole mobility.After optimal annealing,single PbSe nanowires exhibited a thermoelectric figure of merit(ZT)of 0.12 at room temperature.

Boosting the potassium-ion storage performance enabled by engineering of hierarchical MoSSe nanosheets modified with carbon on porous carbon sphere

Developing suitable electrode materials capable of tolerating severe structural deformation and overcoming sluggish reaction kinetics resulting from the large radius of potassium ion(K+)insertion is critical for practical applications of potassium-ion batteries(PIBs).Herein,a superior anode material featuring an intriguing hierarchical structure where assembled MoSSe nanosheets are tightly anchored on a highly porous micron-sized carbon sphere and encapsulated within a thin carbon layer(denoted as Cs@MoSSe@C)is reported,which can significantly boost the performance of PIBs.The assembled MoSSe nanosheets with expanded interlayer spacing and rich anion vacancy can facilitate the intercalation/deintercalation of K+and guarantee abundant active sites together with a low K+diffusion barrier.Meanwhile,the thin carbon protective layer and the highly porous carbon sphere matrix can alleviate the volume expansion and enhance the charge transport within the composite.Under these merits,the as-prepared Cs@MoSSe@C anode exhibits a high reversible capacity(431.8 mAh g^(-1) at 0.05 A g^(-1)),good rate capability(161 mAh g^(-1) at 5 A g^(-1)),and superior cyclic performance(70.5%capacity retention after 600 cycles at 1 A g^(-1)),outperforming most existing Mo-based S/Se anodes.The underlying mechanisms and origins of superior performance are elucidated by a set of correlated in-situ/ex-situ characterizations and theoretical calculations.Further,a PIB full cell based on Cs@MoSSe@C anode also exhibits an impressive electrochemical performance.This work provides some insights into developing high-performance PIBs anodes with transition-metal chalcogenides.

Van der Waals magnets: Wonder building blocks for two-dimensional spintronics?

The unprecedented realization of two-dimensional(2D)van der Waals magnets excitingly extends the synergy between spintronics and 2D materials,started with graphene over the last decade.This article reviews the recent milestones in the development of 2D magnets and its derived heterostructures.In particular,a number of critical challenges centered around the scalability,ambient stability and Curie temperature of these atomically thin magnets are discussed.This mini-review also provides an outlook on what the future might hold for this integrated field of 2D spintronics,and assesses its potential in postsilicon electronics.

Epitaxial fabrication of AgTe monolayer on Ag(111)and the sequential growth of Te film

Transition-metal chalcogenides(TMCs)materials have attracted increasing interest both for fundamental research and industrial applications.Among all these materials,two-dimensional(2D)compounds with honeycomb-like structure possess exotic electronic structures.Here,we report a systematic study of TMC monolayer AgTe fabricated by direct depositing Te on the surface of Ag(111)and annealing.Few intrinsic defects are observed and studied by scanning tunneling microscopy,indicating that there are two kinds of AgTe domains and they can form gliding twin-boundary.Then,the monolayer AgTe can serve as the template for the following growth of Te film.Meanwhile,some Te atoms are observed in the form of chains on the top of the bottom Te film.Our findings in this work might provide insightful guide for the epitaxial growth of 2D materials for study of novel physical properties and for future quantum devices.