Large-scale selective synthesis of uniform single crystalline tellurium nanowires with a diameter of 4-9 nm, and microbelts with a width of 250-800 nm and tens of micrometers in length, can be realized by a poly (vinyl pyrrolidone) (PVP)-assisted hydrothermal process. The formation of tellurium nanowires and nanobelts in the presence of PVP is strongly dependent on the reaction conditions such as temperature, the amount of PVP, and reaction time. The results demonstrated that the keys for selective synthesis of Te nanobelts and nanowires are to modulate the growth rates of (100), (101), and (110) planes in the presence of PVP and to precisely control the reaction kinetics. High-quality luminescent ultrathin t-Te nanowires with a diameter of 4-9 nm display strong luminescent emission in the blue-violet region. This approach provides a facile route for the production of high-quality tellurium nanostructures with an interesting optical property. Furthermore, the synthesized ultrathin nanowires with deep blue color and nanobelts in gray color by this approach can be well dispersed in water or ethanol, making it possible for further engineering of their surfaces to prepare other hybrid core-shell nanostructures.

A microscopic understanding of the growth mechanism of two-dimensional materials is of particular importance for controllable synthesis of functional nanostructures. Because of the lack of direct and insightful observations, how to control the orientation and the size of two-dimensional material grains is still under debate. Here we discern distinct formation stages for MoS2 flakes from the thermolysis of ammonium thiomolybdates using in situ transmission electron microscopy. In the initial stage (400 °C), vertically aligned MoS2 structures grow in a layer-by-layer mode. With the increasing temperature of up to 780 °C, the orientation of MoS2 structures becomes horizontal. When the growth temperature reaches 850 °C, the crystalline size of MoS2 increases by merging adjacent flakes. Our study shows direct observations of MoS2 growth as the temperature evolves, and sheds light on the controllable orientation and grain size of two-dimensional materials.

Although three-dimensional metal halide perovskite (ABX3) single crystals are promising next-generation materials for radiation detection, state-of-the-art perovskite X-ray detectors include methylammonium as A-site cations, limiting the operational stability. Previous efforts to improve the stability using formamidinium–caesium-alloyed A-site cations usually sacrifice the detection performance because of high trap densities. Here we successfully solve this trade-off between stability and detection performance by synergistic composition engineering, where we include A-site alloys to decrease the trap density and B-site dopants to release the microstrain induced by A-site alloying. As such, we develop high-performance perovskite X-ray detectors with excellent stability. Our X-ray detectors exhibit high sensitivity of (2.6 ± 0.1) × 104 μC Gyair−1 cm−2 under 1 V cm−1 and ultralow limit of detection of 7.09 nGyair s−1. In addition, they feature long-term operational stability over half a year and impressive thermal stability up to 125 °C. We further demonstrate the promise of our perovskite X-ray detectors for low-bias portable applications with high-quality X-ray imaging and monitoring prototypes.

A major challenge that prohibits the practical application of single/double-transition metal (3d-M) oxides as oxygen evolution reaction (OER) catalysts is the high overpotentials during the electrochemical process. Herein, our theoretical calculation shows that Fe will be more energetically favorable in the tetrahedral site than Ni and Co, which can further regulate their electronic structure of binary NiCo spinel oxides for optimal adsorption energies of OER intermediates and improved electronic conductivity and hence boost their OER performance. X-ray absorption spectroscopy study on the assynthesized NiCoFe oxide catalysts indicates that Fe preferentially dopes into tetrahedral sites of the lattice, which induces high proportions of Ni 3+ and Co 2+ on the octahedral sites (the active sites in OER). Consequently, this material exhibits a significantly enhanced OER performance with an ultralow overpotential of 201 mV cm −2 at 10 mA cm −2 and a small Tafel slope of 39 mV dec −1 , which are much superior to state-of-the-art Ni−Co based catalysts.

A hydrothermal carbonization route has been designed for the syntheses of uniform core-shell Te@carbon-rich composite nanocables with ultrathin and ultralong Te nanowires as the core component and carbonaceous matter with remarkable reactivity as the shell, using ultralong Te nanowires of several nanometers in diameter and glucose as starting materials. The results demonstrated that the presence of uniform Te nanowires can effectively restrain the usual homogeneous nucleation of carbon spheres from the bulk solution and instead promote the heterogeneous deposition of carbonaceous matter on the backbone of Te nanowires for the formation of well-defined Te@carbon-rich composite nanocables. The diameter of the Te@carbon-rich composite nanocables could be controlled by adjusting the hydrothermal carbonization reaction time or the ratio of the tellurium and glucose, and the shell thickness of the coreshell nanocables can be varied from 2 to 25 nm. Simply removing the Te nanowire core can produce well-defined ultralong and functionalized carbonaceous nanofibers. As-prepared Te@carbon-rich composite nanocables display a strong photoluminescence in the blue-violet region. These well-defined nanocables/ nanofibers can be well dispersed in water or ethanol solution and are of high reactivity, making it possible to further engineer their surfaces or produce new hybrid materials with potential applications.

In this study, mechanical vibration is used for hydrogen generation and decomposition of dye molecules, with the help of BiFeO3 (BFO) square nanosheets. A high hydrogen production rate of ≈124.1 μmol g−1 is achieved under mechanical vibration (100 W) for 1 h at the resonant frequency of the BFO nanosheets. The decomposition ratio of Rhodamine B dye reaches up to ≈94.1 % after mechanical vibration of the BFO catalyst for 50 min. The vibration‐induced catalysis of the BFO square nanosheets may be attributed to the piezocatalytic properties of BFO and the high specific surface area of the nanosheets. The uncompensated piezoelectric charges on the surfaces of BFO nanosheets induced by mechanical vibration result in a built‐in electric field across the nanosheets. Unlike a photocatalyst for water splitting, which requires a proper band edge position for hydrogen evolution, such a requirement is not needed in piezocatalytic water splitting, where the band tilting under the induced piezoelectric field will make the conduction band of BFO more negative than the H2/H2O redox potential (0 V) for hydrogen generation.

Se-doped black phosphorus (BP) crystal, in centimeter scale, is synthesized by a scalable gas-phase growth method under mild conditions. The Se-doped BP exhibits high quality with excellent electrical properties. The Se dope induces over 20-fold enhancement of responsivity (R) for BP-based 2D photodetectors, resulting in a high R and external quantum efficiency of 15.33 A W and 2993%, respectively.

We report a straightforward strategy to design efficient N doped porous carbon (NPC) electrocatalyst that has a high concentration of easily accessible active sites for the CO2 reduction reaction (CO2RR). The NPC with large amounts of active N (pyridinic and graphitic N) and highly porous structure is prepared by using an oxygen‐rich metal–organic framework (Zn‐MOF‐74) precursor. The amount of active N species can be tuned by optimizing the calcination temperature and time. Owing to the large pore sizes, the active sites are well exposed to electrolyte for CO2RR. The NPC exhibits superior CO2RR activity with a small onset potential of −0.35 V and a high faradaic efficiency (FE) of 98.4 % towards CO at −0.55 V vs. RHE, one of the highest values among NPC‐based CO2RR electrocatalysts. This work advances an effective and facile way towards highly active and cost‐effective alternatives to noble‐metal CO2RR electrocatalysts for practical applications.