Bandgap modulation in the two-dimensional core-shell-structured monolayers of WS.

Tungsten disulfide (WS) has tunable bandgaps, which are required for diverse optoelectronic device applications. Here, we report the bandgap modulation in WS monolayers with two-dimensional core-shell structures formed by unique growth mode in chemical vapor deposition (CVD). The core-shell structures in our CVD-grown WS monolayers exhibit contrasts in optical images, Raman, and photoluminescence spectroscopy.

Nanoporous Silver Telluride for Active Hydrogen Evolution.

Silver-based nanomaterials have been versatile building blocks of various photoassisted energy applications; however, they have demonstrated poor electrochemical catalytic performance and stability, in particular, in acidic environments. Here we report a stable and high-performance electrochemical catalyst of silver telluride (AgTe) for the hydrogen evolution reaction (HER), which was synthesized with a nanoporous structure by an electrochemical synthesis method. X-ray spectroscopy techniques on the nanometer scale and high-resolution transmission electron microscopy revealed an orthorhombic structure of nanoporous AgTe with precise lattice constants.

Mitrofanovite, Layered Platinum Telluride, for Active Hydrogen Evolution.

Two-dimensional (2D) layered catalysts have been considered as a class of ideal catalysts for hydrogen evolution reaction (HER) because of their abundant active sites with almost zero Gibbs energy change for hydrogen adsorption. Despite the promising performance, the design of stable and economic electrochemical catalyst based on 2D materials remains to be resolved for industrial-scale hydrogen production. Here, we report layered platinum tellurides, mitrofanovite PtTe, which serves as an efficient and stable catalyst for HER with an overpotential of 39.

Polymorphic Spin, Charge, and Lattice Waves in Vanadium Ditelluride.

Lattice distortion, spin interaction, and dimensional crossover in transition metal dichalcogenides (TMDs) have led to intriguing quantum phases such as charge density waves (CDWs) and 2D magnetism. However, the combined effect of many factors in TMDs, such as spin-orbit, electron-phonon, and electron-electron interactions, stabilizes a single quantum phase at a given temperature and pressure, which restricts original device operations with various quantum phases. Here, nontrivial polymorphic quantum states, CDW phases, are reported in vanadium ditelluride (VTe ) at room temperature, which is unique among various CDW systems; the doping concentration determines the formation of either of the two CDW phases in VTe at ambient conditions.