Lianying Wang

Large continuous, transparent and oriented self-supporting films of layered double hydroxides with tunable chemical composition

Highly ordered transparent self-supporting films of layered double hydroxides (LDHs) with a size of the order of cm2 have been obtained by a simple method; the chemical composition of both the layers and interlayers can be readily tuned, as demonstrated by the preparation of [ZnAl-NO3] LDH, [NiAl-NO3] LDH and [Tb(EDTA)]- intercalated-ZnAl LDH films.

Large oriented mesoporous self-supporting Ni–Al oxide films derived from layered double hydroxide precursors

Large (~1 cm2) transparent highly (111)-oriented mesoporous self-supporting Ni–Al oxide films of uniform small nanoparticles have been prepared using an Ni2Al(OH)6(NO3)·2.1H2O layered double hydroxide (LDH) as a single precursor. The monodisperse small LDH nanoparticles (about 20 nm in diameter) are first cast as an oriented assembly on a glass substrate to form large transparent self-supporting (00l)-oriented LDH films. Subsequent heating in air affords (111)-oriented mesoporous Ni–Al oxide films preserving the shape, dimensions and optical transparency of the films. The process involves a topotactic transformation from the LDH (00l) facet to the NiO and NiAl2O4 spinel (111) facets, demonstrated here for the first time, and does not require any template, structure-directing agent, or lattice-matched single crystal substrate. The nanostructures of the resulting mixed metal oxide films can be controlled by changing the calcination temperature: Al-doped NiO and composite NiO/NiAl2O4 films of uniform small nanoparticles have been obtained at 500 °C and 900 °C respectively. The pore size and pore size distribution increase monotonically with temperature due to the increased sintering of the nanoparticles at higher temperatures. The resulting large transparent Ni–Al oxide films have a narrow distribution of mesopores (<10 nm) and high thermal stability, suggesting their potential application as catalysts or catalyst supports, in sensors, and as ultrafiltration membranes in harsh environments.

Metal oxide-sensitized TiO2 and TiO2-xNx with efficient charge transport conduits

NiO-sensitized anatase is designed to share lattice oxygen at the particle interface and is prepared by the topological transformation of atomic-ordered layered metal hydroxides; the interfacial Ti-O-Ni linkages act as efficient electron transfer conduits to achieve photosensitization.

Single-crystalline organic-inorganic layered cobalt hydroxide nanofibers: facile synthesis, characterization, and reversible water-induced structural conversion.

New pink organic-inorganic layered cobalt hydroxide nanofibers intercalated with benzoate ions [Co(OH)(C6H5COO)·H2O] have been synthesized by using cobalt nitrate and sodium benzoate as reactants in water with no addition of organic solvent or surfactant. The high-purity nanofibers are single-crystalline in nature and very uniform in size with a diameter of about 100 nm and variable lengths over a wide range from 200 μm down to 2 μm by simply adjusting reactant concentrations. The as-synthesized products are well-characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), fast Fourier transforms (FFT), X-ray diffraction (XRD), energy dispersive X-ray spectra (EDX), X-ray photoelectron spectra (XPS), elemental analysis (EA), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and UV-vis diffuse reflectance spectra (UV-vis). Our results demonstrate that the structure consists of octahedral cobalt layers and the benzoate anions, which are arranged in a bilayer due to the π-π stacking of small aromatics. The carboxylate groups of benzoate anions are coordinated to Co(II) ions in a strong bridging mode, which is the driving force for the anisotropic growth of nanofibers. When NaOH is added during the synthesis, green irregular shaped platelets are obtained, in which the carboxylate groups of benzoate anions are coordinated to the Co(II) ions in a unidentate fashion. Interestingly, the nanofibers exhibit a reversible transformation of the coordination geometry of the Co(II) ions between octahedral and pseudotetrahedral with a concomitant color change between pink and blue, which involves the loss and reuptake of unusual weakly coordinated water molecules without destroying the structure. This work offers a facile, cost-effective, and green strategy to rationally design and synthesize functional nanomaterials for future applications in catalysis, magnetism, gas storage or separation, and sensing technology.

One-step solid-state synthesis of carbon nanotubes with surface functionality and their application in water treatment

Uniform carbon nanotubes (CNTs) with high purity and surface functionality have been synthesized by one-step solid-state pyrolysis of a simple organic–inorganic layered double hydroxide (LDH) precursor. The prepared CNTs without any extra treatment exhibit very high performance in the removal of both organic dyes and toxic heavy metal ions.

Hydroxyl-rich nanoporous carbon nanosheets synthesized by a one-pot method and their application in the in situ preparation of well-dispersed Ag nanoparticles

Functional nanoporous carbon nanosheets (CNSs) with high surface areas have been synthesized by the pyrolysis of simple organic–inorganic layered zinc hydroxide nanosheets. The synthesized CNSs with abundant hydroxyl groups display remarkable reactivity and the capability for in situ loading with ultrafine Ag NPs, which show excellent catalytic activity toward the reduction of 4-nitrophenol (4-NP) by NaBH4.

Facile synthesis of hollow hierarchical Ni@C nanocomposites with well-dispersed high-loading Ni nanoparticles embedded in carbon for reduction of 4-nitrophenol

Hollow hierarchical Ni@C nanocomposites with highly dispersed Ni nanoparticles (NPs) embedded in well-graphitized carbon matrix have been synthesized by solid-state pyrolysis of simple, well-defined organic–inorganic layered nickel hydroxide. The integration of highly dispersed Ni NPs, high Ni NPs content (up to ∼88.01 wt%), well-graphitized carbon as well as strong Ni/carbon interaction in the Ni@C make them display excellent catalytic activity and stable magnetic recyclability toward the reduction of 4-nitrophenol by NaBH4.