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Low-dimensional transition metal dichalcogenides, e.g., MoSe2, are attractive electrocatalysts for hydrogen evolution reactions (HER). However, the stable 2H-phase MoSe2 with semiconducting properties exhibits electrocatalytic performance only at its sheet edges, but the basal planes without defects are inactive, limiting their performance in HER. This work reported a strategy for comprehensive activation of TMDs by intercalating 2D MoSe2 with 2D CoP. Its unique sandwiched structure opens up activity between the layers, enhancing active surface area to 10-fold. Meanwhile, the maximized interfaces enable rapid ion/electron transport and excellent electrical conductivity, thus yielding superior HER activity. It exhibits a very low overpotential of 105 mV at 10 mA cm−2, small Tafel slope of 51 mV dec−1 and excellent electrochemical stability for >24 h. The CoP significantly increases the hydrogen adsorption sites of MoSe2 in the basal planes, and the P atoms enable Mo and Co atoms adjacent to them become the most active ones, according to Density Functional Theory calculations. Our work, using two layered materials as precursors to intercalate with each other, provides new ideas for designing efficient and non-precious metal electrocatalysts. Moreover, this method can be universally applicable to synthesize other hybrid materials such as CoSe2/MoSe2, FeP/MoSe2, NiP/MoSe2, CoSe2/WS2, FeP/TiS2 and so on.

Enhancing catalytic activity by decorating noble metals in catalysts provides an opportunity for promoting the electrocatalytic hydrogen evolution reaction (HER) application. However, there are few...

The 3D hierarchical structure in catalysts not only the preserves intrinsic characteristics of each component, but also achieves increased specific surface area and active sites for the hydrogen evolution reaction (HER). Herein, we report a new strategy to synthesize efficient 3D hierarchical catalysts composed of Mo2C nanosheets and Co nanoparticles (H-Mo2C@Co). It was realized by using raw materials, defect-rich MoOx, Co(NO3)2·6H2O and 2-methylimidazole, to design Mo/Co bimetallic metal–organic frameworks (BMOFs), followed by pyrolysis at 800 °C. The defects in MoOx induced preferential nucleation and growth of the BMOFs so that they can ensure the construction of a stable 3D hierarchical structure. Mo2C and Co have a synergistic effect in improving the HER via providing large surface areas (351.5 m2 g−1), more active sites and optimizing charge transfer. It can achieve 10 mA cm−2 at low overpotential over a wide pH range (144 mV in 0.5 M H2SO4 and 103 mV in 1.0 M KOH) and the properties can be well maintained in both acid and alkaline electrolyte after 2000 cycles. The hierarchical catalyst contains no noble metal, can be synthesized on a large scale and recycled by magnetic stirring, demonstrating great potential in water splitting, wastewater treatment, dye adsorption and other fields.

Pleiones are popular ornamental orchids and different species of Pleione are long being used as traditional medicine in many Asian countries. However, previous chemical investigations of the genus Pleione are restricted to only a few species. In the present study, high performance liquid chromatography (HPLC) fingerprint of Pleione plants was established, which in particular, eight common peaks were confirmed in 16 species/hybrids. Three of the compounds corresponding to the chromatographic peaks were identified by electrospray ionization tandem mass spectrometry (ESI-tandem-MS). HPLC analysis confirmed the studied taxa shared most of chemical compounds but the content of chemical compounds was significantly different between species. Comparison of hierarchical clustering result with phylogenetic tree revealed that closely related species have higher similarities in chemical constituents. In consideration of low chemical similarity between spring-flowering and autumn-flowering species, we suggest a discrimination of these two groups during medicinal use of the genus Pleione. Species with a large pseudobulb and with high content of a certain compound should be given priority in future artificial cultivation and medicinal cultivar breeding. We hope our findings will contribute to the quality control and promote conservation of such endangered plant group.

A nanocomposite of carbon nanotubes coated with nickel oxide was prepared by a simple hydrothermal method. The structure, morphology and electrochemical performance of the nanocomposite were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, electrochemical tests including cyclic voltammogram, galvanostatic charge–discharge and electrochemical impedance spectroscopy, respectively. It presents the highest specific capacitance of 1844 F g−1 at 1 A g−1 and 1145 F g−1 at current density of 10 A g−1 with 88.9% (at 1 A g−1) capacitance retention after 1000 cycles. The specific capacitance of the nanocomposite is almost double of that of the virginal NiO (972 F g−1 at 1 A g−1). Its cycling behavior is also very good. When combined with activated carbon as the negative electrode, the energy density can be up to 52.6 Wh kg−1. Such good electrochemical behavior indicates that the nanocomposite is a promising electrode material for supercapacitors.

Ultrathin nanosheets possess novel electronic structures and physical properties as compared with their corresponding bulk samples. However, the controlled synthesis of ultrathin monolayer nanosheets still remains a great challenge due to the lack of an intrinsic driving force for anisotropic growth of two-dimensional (2D) structures. Here we demonstrate, for the first time to our knowledge, the in situ synthesis of large-scale ultrathin single-crystalline Co0.85Se nanosheets on graphene oxide (GO) sheets, with a thickness of 3 nm. Owing to the synergetic chemical coupling effects between GO and Co0.85Se, the Co0.85Se/graphene hybrid nanosheets exhibit the highest catalytic performance among the available cobalt chalcogenide-based catalysts for the oxygen reduction reaction (ORR). Moreover, Co0.85Se/graphene hybrid nanosheets can catalyze the decomposition of hydrazine hydrate rapidly, with 97% of hydrazine hydrate being degraded in 12 min and the degradation rate remaining constant over 10 consecutive cycles, thus having great potential as long-term catalysts in wastewater treatment.

Highly uniform pancake-like CeOHCO3 hierarchical microstructures have been successfully prepared by a simple gelatin-assisted mixed-solvothermal route. Ceria hierarchical microstructures with similar morphology were obtained after thermal treatment of the CeOHCO3 hierarchical microstructures at 700 °C for 4 h. The CeOHCO3 microstructures can be selectively obtained by varying the composition of solvent, concentration of gelatin and triethylenetetramine (TETA). The as-prepared products were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electronic microscope (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and selected area electron diffraction (SAED). The possible formation process of the CeOHCO3 microstructures was briefly discussed. Gold coated ceria microstructures were also prepared which show excellent catalytic activity in the conversion of carbon monoxide, the T50 and T90 are at 240 °C and 300 °C, respectively.

This article presents a facile approach about the designed synthesis of one-dimensional (1D) dysprosium-based coordination polymer wires under solvothermal conditions with dysprosium chloride and tributyl phosphate (TBP) as starting materials. The wires are in the length of several hundreds of micrometers and diameter in the range of 0.4–2 μm. Time-dependent results revealed that the coordination polymer wires were not stable and evolved into three-dimensional (3D) flower-like tetragonal DyPO 4 superstructures with the prolonging of reaction time. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy disperse spectroscopy (EDS), thermogravimetric analysis (TG) and differential thermal analysis (DTA) were employed to characterize the samples. Interestingly, with the assistance of lauryl sodium sulfate, rice-like macroporous hexagonal DyPO 4 microstructures with a BET surface area of 2.13 m 2 /g were successfully fabricated. A possible formation mechanism for the morphology evolution of the DyPO 4 superstructures was also discussed. Magnetic measurement revealed that the products were antiferromagnetic.

Uniform europium-based infinite coordination polymer (ICP) submicrospheres have been prepared via a facile and fast microwave heating method in 5 min, with pyridine-2, 5-dicarboxylic acid and europium nitrate as reagents and N, N-dimethylformamide (DMF) as solvent. The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric (TG) and derivative thermogravimetric analysis (DTG) were also carried out. XRD results reveal that the product is amorphous. SEM and TEM results show that the submicrospheres are with diameters of 200–400 nm. Furthermore, the surface of the microspheres is smooth and the submicrospheres are solid. Strong red emission centering at 618 nm was observed in the europium-based ICP microspheres on excitation with 394 nm UV light. This method may be employed to the preparation of other coordination polymers micro/nanostructures.

CuSn(OH) 6 submicrospheres with diameters of 400–900 nm have been successfully fabricated using a simple aqueous solution method at room temperature. Influencing factors such as the dosage of reactants and reaction time on the preparation were systematically investigated. The products were characterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and differential thermal analysis (DTA). Results reveal that the CuSn(OH) 6 spheres are built from numerous nanoparticles. It is found that the diameter of CuSn(OH) 6 spheres can be readily tuned by adjusting the molar ratio of Sn O 3 2 − to Cu 2+ . A possible growth mechanism for the CuSn(OH) 6 submicrospheres has been proposed. Amorphous CuSnO 3 submicrospheres were obtained after thermal treatment of the CuSn(OH) 6 submicrospheres at 300 °C for 4 h. Standard magnetization measurements demonstrate that the CuSn(OH) 6 submicrospheres are antiferromagnetic and have a weak spin-Peierls transition at about 78 K.

Several novel cadmium sulfide (CdS) micro/nanostructures, including cauliflower-like microspheres, football-like microspheres, tower-like microrods, and dendrites were controllably prepared via an oxalic acid-assisted solvothermal route using ethylene glycol (EG) and H2O as pure and mixed solvents with different S sources. The as-prepared products were characterized by X-ray powder diffraction (XRD), scanning electronic microscope (SEM) and UV–vis spectrophotometer (UV). It was found that CdS micro/nanostructures can be selectively obtained by varying the composition of solvent, concentration of oxalic acid, and sulfur sources. UV–vis absorption spectra reveal that their absorption properties are shape-dependent. The possible formation process of the CdS micro/nanostructures was briefly discussed. This route provides a facile way to tune the morphologies of CdS over a wide range.

Uniform γ-CuI octahedral crystals with average size of about 15 μm were prepared by a hydrothermal growth method with sodium citrate (SC). SEM observation shows that the shape evolutions of CuI particles from truncated octahedron to octahedron have been arrested. The additive, sodium citrate, plays an important role in the formation of the uniform γ-CuI octahedral crystals.

Ultrathin nanosheets possess novel electronic structures and physical properties as compared with their corresponding bulk samples. However, the controlled synthesis of ultrathin monolayer nanosheets still remains a great challenge due to the lack of an intrinsic driving force for anisotropic growth of two-dimensional (2D) structures. Here we demonstrate, for the first time to our knowledge, the in situ synthesis of large-scale ultrathin single-crystalline Co₀.₈₅Se nanosheets on graphene oxide (GO) sheets, with a thickness of 3 nm. Owing to the synergetic chemical coupling effects between GO and Co₀.₈₅Se, the Co₀.₈₅Se/graphene hybrid nanosheets exhibit the highest catalytic performance among the available cobalt chalcogenide-based catalysts for the oxygen reduction reaction (ORR). Moreover, Co₀.₈₅Se/graphene hybrid nanosheets can catalyze the decomposition of hydrazine hydrate rapidly, with 97% of hydrazine hydrate being degraded in 12 min and the degradation rate remaining constant over 10 consecutive cycles, thus having great potential as long-term catalysts in wastewater treatment.

We synthesize the three-fold symmetric shield-like Au@Pd core–shell nanocrystals, enclosed predominantly by high-index {541} facets with kinks, through the simultaneous reduction of Au and Pd ions in the presence of triangular Au nanocrystal seeds in aqueous solution at room-temperature. The obtained shield-like Au@Pd core–shell nanocrystals exhibit superior electrocatalytic activity for the oxidation of ethanol and unique near-field enhancement property with a highly sensitive surface-enhanced Raman scattering (SERS) response. These excellent properties can be ascribed to the presence of sharp corners and edges as well as high-index faceted Pd-rich shell in the shield-like Au@Pd core–shell structure. We also investigate the mechanism for the formation of three-fold symmetric shield-like Au@Pd core–shell nanocrystals.

Highly monodispersed concave gold nanobars with 24 high-index {730} facets are synthesized through a seed-mediated growth in aqueous solution. The transformation from the truncated rectangular nanobars to rectangular nanobars, then transitional products, and final concave rectangular nanobars is observed with the fine control of silver nitrate in the growth solution, and their corresponding transverse surface plasmons can be well tuned, too. These concave gold nanobars exhibit good optical property, excellent catalytic activity, and high surface-enhanced Raman-scattering (SERS) response.

Ultralong helical organosilica nanofibers (length up to millimeter) with ordered helical mesoporous channels are synthesized using achiral cationic surfactant as single-structure-directing agent and anionic citrate as counterions. The surfactant molecules form micelles for silica condensation and the counterions reduce the polarity of the surfactant-silicate micelles via electrostatic balance, leading to the self-assembly and growth of the final product. The detailed mechanistic shape-shifting studies reveal that an entropy increase is the main driving force behind the plastic deformation of the solids.

Direct fabrication of core-shell or yolk-shell functional nanomaterials via a facile template-free method remains a challenge. In this work, we present a novel approach that involves straightforward chemical transformation and thermal treatment of the infinite coordination polymer particles to obtain composition-tunable CeO(2) yolk-shell structures. Uniform CeO(2) yolk-shell hollow spheres with a high surface area are promising support materials for tiny gold nanoparticles (ca. 4 nm), forming Au-CeO(2) nanocomposites which exhibit a remarkable catalytic activity and high stability for the reduction of p-nitrophenol. A possible mechanism for the formation of CeO(2) yolk-shell microspheres is also proposed.

Superstar: branched concave Au/Pd bimetallic nanocrystals were synthesized in high yield by seed-mediated co-reduction of Au and Pd metal precursors in an aqueous solution at room temperature. The branches are concave and have high-index facets on their surfaces. These nanocrystals show superior electrocatalytic activity for the oxidation of ethanol and highly efficient SERS enhancement.

Nanostructures with concave surfaces are not common, and their synthesis is still challenging. In this paper, we have successfully synthesized two kinds of five-fold-twinned Au decahedra and dodecagonal plates by changing the reaction conditions. 40 high-index {221} facets were observed in the concave decahedron. The truncated decahedral gold nanocrystals (NCs) with a large size of 250-350 nm were obtained for the first time, which breaks the assumption that the truncated five-fold-twinned Au nanoparticles (NPs) can only be obtained with a size below 5 nm. The growth mechanism and the evolution process of the gold nanostructures were discussed. This work provides a facile way to synthesize concave decahedra, truncated decahedra and dodecagonal plates with controlled nanostructures.

A fabrication of uniform apple-like LaCO3OH hierarchical nanostructures was achieved by a facile hydrothermal route using gelatin as the reactant and structure-directing agent. The hierarchical nanostructures with diameters of 2–5 μm are built from numerous nanoplatelets with thicknesses of 10–20 nm and lengths of 30–80 nm. Influential factors such as reaction time, reaction temperature, dosage of gelatin and potassium hydroxide were systematically investigated. A dipole-field-driven process was suggested for the formation of the apple-like LaCO3OH hierarchical nanostructures. Strong emission centring at 432 nm was realized in the apple-like LaCO3OH hierarchical nanostructures on excitation with 365 nm ultraviolet light. It turns out that it is easy to tune the luminescent characteristics of the LaCO3OH hierarchical nanostructures in a wide spectral range by simply varying excitation lines or doping concentration of Eu3+ and Tb3+. Particularly, white light emission can be obtained in the Eu3+ and Tb3+ codoped LaCO3OH hierarchical nanostructures on excitation in a wide ultraviolet band.

Novel rare earth based 4,4′,4′′-benzene-1,3,5-triyl-tri-benzonate (RE-BTB) infinite coordination polymer (ICP) hollow microspheres have been successfully prepared via a facile surfactant-free mixed-solvothermal route, among which Tb-BTB was studied in detail. These as-prepared hollow microspheres using terbium as the central ion have diameters of 260–500 nm. Influential factors such as reaction temperature, reaction time, dosage of reagents, and solvent composition on the morphology and size of the Tb-BTB ICP hollow spheres have been systematically investigated. An inside-out formation mechanism was proposed for the hollow microspheres. The photoluminescence properties of the Tb-BTB hollow spheres have been systematically studied. It turns out that it is easy to tune the luminescent characteristics of the Tb-BTB ICP hollow spheres within a wide spectral range by simply varying the excitation lines or the doping concentration of Eu3+. Interestingly, white-light emission was realized in the Eu3+ doped Tb-BTB hollow spheres.