Fe-Ion-Catalyzed Synthesis of CdSe/Cu Core/Shell Nanowires

Research progress of out-of-plane GeSn nanowires

With the increasing integration density of silicon-based circuits, traditional electrical interconnections have shown their technological limitations. In recent years, GeSn materials have attracted great interest due to their potential direct bandgap transition and compatibility with silicon-based technologies. GeSn materials, including GeSn films, GeSn alloys, and GeSn nanowires, are adjustable, scalable, and compatible with silicon. GeSn nanowires, as one-dimensional (1D) nanomaterials, including out-of-plane GeSn nanowires and in-plane GeSn nanowires, have different properties from those of bulk materials due to their distinctive structures. However, the synthesis and potential applications of out of plane GeSn nanowires are rarely compared to highlighting their current development status and research trends in relevant review papers. In this article, we present the preparation of out-of-plane GeSn nanowires using top-down (etching and lithography) and bottom-up (vapor-liquid-solid) growth mechanism in the vapor-phase method and supercritical fluid-liquid-solid, solution-liquid-solid, and solvent vapor growth mechanisms in the liquid-phase method) methods. Specifically, the research progress on typical out of plane GeSn nanowires are discussed, while some current development bottlenecks are also been identified. Finally, it is also provided a brief description of the applications of out-of-plane GeSn nanowires with various Sn contents and morphologies.

Optoelectronic Properties of a Cylindrical Core/Shell Nanowire: Effect of Quantum Confinement and Magnetic Field

This study investigates the effect of quantum size and an external magnetic field on the optoelectronic properties of a cylindrical AlxGa1-xAs/GaAs-based core/shell nanowire. We used the one-band effective mass model to describe the Hamiltonian of an interacting electron-donor impurity system and employed two numerical methods to calculate the ground state energies: the variational and finite element methods. With the finite confinement barrier at the interface between the core and the shell, the cylindrical symmetry of the system revealed proper transcendental equations, leading to the concept of the threshold core radius. Our results show that the optoelectronic properties of the structure strongly depend on core/shell sizes and the strength of the external magnetic field. We found that the maximum probability of finding the electron occurs in either the core or the shell region, depending on the value of the threshold core radius. This threshold radius separates two regions where physical behaviors undergo changes and the applied magnetic field acts as an additional confinement.

Lattice-Matched CoP/CoS2 Heterostructure Cocatalyst to Boost Photocatalytic H2 Generation

Transition-metal phosphides and sulfides are considered as promising cocatalysts for the photocatalytic hydrogen evolution reaction (HER), and the cocatalytic effect can be improved by directed heterostructure engineering. In this study, a novel lattice-matched CoP/CoS₂ heterostructure having a nanosheet morphology was developed as an HER cocatalyst and integrated in situ onto graphitic carbon nitride (g-C₃N₄) nanosheets via a successive phosphorization and vulcanization route. First-principles density functional theory calculations evidenced that the construction of the lattice-matched CoP/CoS₂ heterostructure resulted in the redistribution of interface electrons, enhanced metallic characteristics, and improved H* adsorption. As a result of these effects, the CoP/CoS₂ heterostructure cocatalyst formed a 2D/2D Schottky junction with the g-C₃N₄ nanosheets, thus promoting photoelectron transfer to CoP/CoS₂ and realizing fast charge-carrier separation and good HER activity. As expected, the CoP/CoS₂ heterostructure exhibited excellent cocatalytic activity, and the optimal loading of the cocatalyst on g-C₃N₄ enhanced its HER activity to 3.78 mmol g^-1 h^-1. This work furnishes a new perspective for the development of highly active noble-metal-free cocatalysts via heterostructure engineering for water splitting applications.

Electromagnetic absorbers with Schottky contacts derived from interfacial ligand exchanging metal-organic frameworks

Various types of polycrystals have been regarded as excellent electromagnetic (EM) microwave absorbents, while differentiated heterointerfaces among grains usually manipulate conductive loss and polarization relaxation, especially interfacial polarization. Herein, polar facets that dominated the optimization of EM attenuation were clarified by carefully designing polycrystalline Schottky junctions with metal-semiconductor contacts for the first time. An ingenious ligand exchange technique was utilized to construct Zn-MOF (ZIF-L) precursors for Fe-ZnO polycrystals, in which Fe-containing Fe(CN)₆^3- etching ligand acted as metallic source in Schottky junctions. By adjusting the Schottky contacts in polycrystals, the enhanced grain boundaries mainly induced stronger interfacial polarization and affected the microcurrent lightly. This is because Schottky barriers can cause local charge accumulation on heterointerfaces for polarization relaxation. Additionally, the coexistence of Zn and O vacancies brought a lot of lattice defects and distortions for dipole polarization. Thus, optimal EM wave absorbability was obtained by polycrystals with 8 h ligand exchange and an effective absorption band reaching 4.88 GHz. This work can provide guidance for designing advanced polycrystalline EM absorption materials and also highlight the mechanism and requirement of Schottky junctions dominating polarization.