Bihui Li

Self-assembled 3D flower-like Ni2+?Fe3+ layered double hydroxides and their calcined products

This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni2+-Fe3+ layered double hydroxides (LDHs). Flower-like Ni2+-Fe3+ LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 degrees C in nitrogen gas, porous NiO/NiFe2O4 nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni2+-Fe3+ LDHs as well as porous NiO/NiFe2O4 nanosheets.

Room temperature fabrication of single crystal nanotubes of CaSn(OH)6 through sonochemical precipitation.

CaSn(OH)(6) nanotubes were fabricated by sonochemical precipitation method at room temperature. A direct rolling process from nanosheets to nanotubes was expected for the synthesis of CaSn(OH)(6) nanotubes. The transient CaSn(OH)(6) nanosheets are formed as intermediates produced by the spontaneous self-assembly and transformation of amorphous colloid clusters. During the crystallization process of intermediate nanosheets, the relaxation of surface strain in the nanosheet interfaces can induce the nanosheets to roll up to form nanotubes under ultrasonic conditions. In this synthesis, the addition of Na(2)CO(3) seems to play an important role in the formation, size, and shape control of the nanotubes. Investigations into the stability performance of the nanotubes indicate that the morphologies are very sensitive to pH and temperature. The method suggests a general strategy for the design and fabrication of functional single-crystalline nanotubes through an intermediate nanosheet rolling process. The in vitro fabrication of such single crystal nanotubes could shed light on fundamental mechanisms for closed hollow nanostructures. Furthermore, nanotubes produced in high yield and at low cost are envisioned to have applications in areas ranging from medicine to pharmaceuticals through to materials science.

TiO2@MgO core-shell film: Fabrication and application to dye-sensitized solar cells

In this study, TiO2@MgO core-shell film was obtained by using a simple chemical bath deposition method to coat a thin MgO film around TiO2 nanoparticles. The core-shell configuration was characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). Lattice fringes were observed for the TiO2 particles, and the MgO shell showed an amorphous structure, revealing a clear distinction between the core and shell materials. Applying the core-shell film as photoanode to the dye-sensitized solar cells (DSSCs), it shows a superior performance compared to the pure TiO2 electrode. Under the illumination of simulated sunlight (75 mW·cm−2), the short circuit photocurrent (Jsc), the open circuit photovoltage (Voc), and the fill factor (fF) are 8.80 mA·cm−2, 646 mV, and 0.69, respectively, and the conversion efficiency (η) increased by 21.8% (from 4.32% to 5.26%) when dipping for optimum condition.

Controlled growth of ZnO array on FTO glass substrate by electrodeposition

In this study, ZnO nanotube and nanorod array films were respectively synthesized directly on F-doped SnO2 glass substrate (FTO) using a direct electrodeposition from a simple aqueous zinc salt solution. The effects of potential value, electrodeposition mode and solution stirring speed on the product morphology were investigated. Controlling the reaction under potentiostatic condition of −0.7 V at stirring speed of 300 r/min, large-scale nanotube arrays perpendicular to the substrate can be synthesized at a low temperature of 70 °C. By varying the reaction parameters, we can also obtain ZnO nanorod arrays. The results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy have been provided to characterize the structure and morphology of the nanotube and nanorod arrays. Experiment results show that the as-obtained ZnO has a single crystalline structure and c-axis oriented direction. The room-temperature photoluminescence spectrum of the ZnO nanotube array film displayed its high crystal property available as a photonic material. Electrodeposition is an effective method to prepare ZnO nanotube array films in quantity.