Two-dimensional metallic transition metal dichalcogenides are emerging as prototypes for uncovering fundamental physical phenomena, such as superconductivity and charge-density waves, as well as for engineering-related applications. However, the batch production of such envisioned transition metal dichalcogenides remains challenging, which has hindered the aforementioned explorations. Herein, we fabricate thickness-tunable tantalum disulfide flakes and centimetre-sized ultrathin films on an electrode material of gold foil via a facile chemical vapour deposition route. Through temperature-dependent Raman characterization, we observe the transition from nearly commensurate to commensurate charge-density wave phases with our ultrathin tantalum disulfide flakes. We have obtained high hydrogen evolution reaction efficiency with the as-grown tantalum disulfide flakes directly synthesized on gold foils comparable to traditional platinum catalysts. This work could promote further efforts for exploring new efficient catalysts in the large materials family of metallic transition metal dichalcogenides, as well as exploiting their applications towards more versatile applications.

Vertically aligned ZnO/CdTe core-shell nanocable arrays-on-indium tin oxide (ITO) are fabricated by electrochemical deposition of CdTe on ZnO nanorod arrays in an electrolyte close to neutral pH. By adjusting the total charge quantity applied during deposition, the CdTe shell thickness can be tuned from several tens to hundreds of nanometers. The CdTe shell, which has a zinc-blende structure, is very dense and uniform both radially and along the axial direction of the nanocables, and forms an intact interface with the wurtzite ZnO nanorod core. The absorption of the CdTe shell above its band gap ( approximately 1.5 eV) and the type II band alignment between the CdTe shell and the ZnO core, respectively, demonstrated by absorption and photoluminescence measurements, make a nanocable array-on-ITO architecture a promising photoelectrode with excellent photovoltaic properties for solar energy applications. A photocurrent density of approximately 5.9 mA/cm(2) has been obtained under visible light illumination of 100 mW cm(-2) with zero bias potential (vs saturated calomel electrode). The neutral electrodeposition method can be generally used for plating CdTe on nanostructures made of different materials, which would be of interest in various applications.

A growth-temperature-mediated two-step chemical vapor deposition strategy is designed to synthesize MoS /WS and WS /MoS stacks on Au foils. Predominantly A-A stacked MoS /WS and A-B stacked WS /MoS are selectively achieved and confirmed. Relative enhancements or reductions in photocatalytic activities of MoS /WS or WS /MoS are observed under illumination, because the type-II band alignment enables directional electron flow from electrode to active site.

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1D nanowires of all-inorganic lead halide perovskites represent a good architecture for the development of polarization-sensitive optoelectronic devices due to their high absorption efficient, emission yield, and dielectric constants. However, among as-fabricated perovskite nanowires with the lateral dimensions of hundreds nanometers so far, the optical anisotropy is hindered and rarely explored owing to the invalidating of electrostatic dielectric mismatch in the physical dimensions. Here, well-aligned CsPbBr and CsPbCl nanowires with thickness T down to 15 and 7 nm, respectively, are synthesized using a vapor phase van der Waals epitaxial method. Strong emission anisotropy with polarization ratio up to ≈0.78 is demonstrated in the nanowires with T < 40 nm due to the electrostatic dielectric confinement. With the increasing of thickness, the polarization ratio remarkably reduces monotonously to ≈0.17 until T ≈140 nm; and further oscillates in a small amplitude owing to the wave characteristic of light. These findings not only represent a demonstration of perovskite-based polarization-sensitive light sources, but also advance fundamental understanding of their polarization properties of perovskite nanowires.

Integrating metallic halide perovskites with established modern semiconductor technology is significant for promoting the development of application-level optoelectronic devices. To realize such devices, exploring the growth dynamics and interfacial carrier dynamics of perovskites deposited on the core materials of semiconductor technology is essential. Herein, we report the incommensurate heteroepitaxy of highly oriented singlecrystal cesium lead bromide (CsPbBr 3 ) on c-wurtzite GaN/ sapphire substrates with atomically smooth surface and uniform rectangular shape by chemical vapor deposition. The CsPbBr 3 microplatelet crystal exhibits green-colored lasing under room temperature and has a structural stability comparable with that grown on van der Waals mica substrates. Time-resolved photoluminescence spectroscopy studies show that the type-II CsPbBr 3 −GaN heterojunction effectively enhances the separation and extraction of free carriers inside CsPbBr 3 . These findings provide insights into the fabrication and application-level integrated optoelectronic devices of CsPbBr 3 perovskites.

Development of earth-abundant, efficient, and stable electrocatalysts for hydrogen evolution reactions (HER) in alkaline or even neutral pH electrolyte is very important for hydrogen production from water splitting. Construction of bimetal phosphides via tuning the bonding strength to hydrogen and increasing effective active sites through nanostructuring and surface engineering should lead to high HER activity. Here, ternary NiCoP nanowires (NWs) decorated by homogeneous nanoparticles have been obtained on Ni foam for a highly efficient HER property via long-term cyclic voltammetric (CV) sweeping. The electron density transfer between the positively charged Ni and Co and negatively charged P atoms, one-dimensional electron transfer channel of the NWs, and abundant active sites supplied by the nanoparticles and NWs endow the catalyst with low overpotentials of 43 and 118 mV to achieve the respective current densities of 10 and 100 mA cm together with long durability for at least 33 h in 1 M KOH. A cycled anodic dissolution-redeposition mechanism is disclosed for the formation of the NiCoP nanoparticles during the CV sweeping process. Such a surface roughening method is found to be adaptable to enhance the HER property of other phosphides, including NiP nanoplates/NF, NiCoP nanoparticles/NF, and CoP NW/NF.

We report a simple one-step hydrothermal method to fabricate cobalt (Co)-doped vanadium diselenide (VSe 2 ) nanosheets on a carbon cloth for the hydrogen evolution reaction (HER) in acid solution. We find that the Co-doped VSe 2 shows significantly enhanced catalytic activity compared with the pristine VSe 2 , including a low overpotential of 230 mV at 10 mA/cm 2 , a small Tafel slope of 63.4 mV/dec, and high stability. Our density functional theory calculations show that Co dopants dramatically reduce the Gibbs free energy for hydrogen adsorption (ΔG H ), leading to improved catalytic activity for hydrogen evolution. Moreover, the Co doping promotes electron transfer and HER kinetics. Our results provide a valuable route to improve the catalytic performance of metal diselenide in HER.