Simultaneous determination of hydroquinone and catechol by a reduced graphene oxide-polydopamine-carboxylated multi-walled carbon nanotube nanocomposite.

A reduced graphene oxide-polydopamine-carboxylated multi-walled carbon nanotube (RGO-PDA-cMWCNT) nanocomposite was fabricated via a facile, one-pot procedure and was characterized by a variety of techniques. A novel electrochemical sensor based on RGO-PDA-cMWCNT was constructed to determine hydroquinone (HQ) and catechol (CT) simultaneously. This newly prepared nanocomposite shows excellent electrocatalytic efficacy in the electrode reaction of the two isomers. Specifically, the peak-to-peak potential difference between the two dihydroxybenzenes is 115 mV for oxidation, which is obviously larger than similar electrochemical sensors. The established method displays a wide linear range from 0.5 to 5000 µM with a detection limit (S/N = 3) of 0.066 µM for HQ and 0.073 µM for CT. In addition, this electrochemical approach has been tested to measure the two dihydroxybenzenes in real samples and satisfactory results were recorded.

Synthesis of InP nanofibers from tri(m-tolyl)phosphine: an alternative route to metal phosphide nanostructures.

The synthesis of InP nanofibers via a new Ullmann-type reaction of indium nanoparticles with tri(m-tolyl)phosphine (P(PhMe)(3)) was typically performed to illustrate an alternative route for the preparation of nanostructured metal phosphides, including III-V (13-15) and transition-metal phosphides. Triarlyphosphine compounds such as other two tri(m-tolyl)phosphine isomers, diphenyl(p-tolyl)phosphine, and triphenylphosphine were comparably employed to synthesize InP nanocrystals. From the aspect of the carbonization of triarlyphosphines, Raman spectroscopy and thermo-gravimetric analysis (TGA) investigations of the InP products showed that the stability of these triarlyphosphines conformed to the order of tri(p-tolyl)phosphine approximately tri(o-tolyl)phosphine < diphenyl(p-tolyl)phosphine < tri(m-tolyl)phosphine < triphenylphosphine. The correlation between the stability of triarlyphosphines and the growth of InP nanocrystals was investigated, and experimental results showed that the relatively stable triarlyphosphines (tri(m-tolyl)phosphine and triphenylphosphine) were favorable for the preparation of one-dimensional (1D) InP nanostructures (nanofibers and nanowires). The reactivity (stability) of triarlyphosphines was also compared with those of P(SiMe(3))(3) (typically see: J. M. Nedeljkovic, O. I. Micic, S. P. Ahrenkiel, A. Miedaner and A. J. Nozik, J. Am. Chem. Soc., 2004, 126, 2632) and P(C(8)H(17))(3) (C. Qian, F. Kim, L. Ma, F. Tsui, P. D. Yang and J. Liu, J. Am. Chem. Soc., 2004, 126, 1195) according to the difference in preparative temperature for phosphide synthesis. Raman and photoluminescence properties of the as-synthesized InP nanocrystals were further studied, and the synthetic mechanism of our method was reasonably investigated by GC-MS analysis. Moreover, the current route was successfully extended to prepare GaP, MnP, CoP and Pd(5)P(2) nanocrystals.

3D flower-like Y(2)O(3):Eu(3+) nanostructures: template-free synthesis and its luminescence properties.

In this work, a facile route using simple hydrothermal reaction and sequential calcinations to synthesize 3-dimensional flower-like Y(2)O(3):Eu(3+) nanoarchitectures without employing templates or matrix for self-assembly is presented. The flower-like nanostructures are composed of nanosheets with thickness of about 30 nm, which is verified by the field-emission electron microscopy (FESEM). Influencing factors such as the dosage of reactants, the solvent, and pH are systematically investigated. The time-dependent experiments indicate a self-assembly mechanism. This method is also applicable in the preparation of other lanthanide oxides. The PL spectra of the as-synthesized Y(2)O(3):Eu(3+) are systematically studied. Both the Eu(3+) concentration and the calcinations temperature have great effect on the luminescence intensity of (5)D(0)-(7)F(2) transition. The decay curve of the (5)D(0) transition shows that the lifetime of the as-obtained Y(2)O(3):Eu(3+) is about 2.4 ms.

Controlled synthesis of alpha-Fe2O3 nanorods and its size-dependent optical absorption, electrochemical, and magnetic properties.

Uniform alpha-Fe(2)O(3) nanorods with diameter of about 30 nm and length up to 500 nm were synthesized by a template-free hydrothermal method and a following calcination of the intermediate product in the air at 500 degrees C for 2 h. By carefully tuning the concentration of the reactants, a series of alpha-Fe(2)O(3) nanorods with gradient in aspect ratios can be obtained. The effect of the solvent was also evaluated. Based on the experimental facts, the formation mechanism of this one-dimensional structure was proposed. The size-dependent properties of the as-obtained alpha-Fe(2)O(3) nanorods were investigated. The optical absorption properties of the samples showed that the band gaps of the samples decreased in the sequence in which the size increased. The electrochemical performance of the samples showed that the discharge capacity decreased as the size of the sample increased, which may result from the high surface area and small size. The magnetic hysteresis measurements taken at 5 K showed that the coercivities of the samples were related to the aspect ratios of the samples, which may result from the larger shape anisotropy. However, the temperature-dependent field cooling magnetization showed that there was no Morin transition in the as-prepared samples, which may result from the surface effect.

Room-temperature irradiation route to synthesize a large-scale single-crystalline ZnO hexangular prism.

A large-scale single-crystalline ZnO hexangular prism was successfully synthesized through a simple gamma-irradiation method at room temperature and under ambient pressure. The product of a ZnO hexangular prism with a rim of 230 +/- 10 nm and a length up to 8.5 microm was well monodisperse and showed a very strong and broad green light emission at around 577 nm. A possible formation process was also proposed.

Synthesis of nitrogen-doped carbon nanostructures by the reactions of small molecule carbon halides with sodium azide.

Nitrogen-doped carbon nanostructures including particles, whiskers, square frameworks, lamellar layers, hollow spheres, and tubular structures have been successfully synthesized by designed direct chemical reactions of small molecule carbon halides (such as CCl4, C2Cl6) and nitridation reagent NaN3 in the absence of any templates and catalysts. The N/C ratios of the as-prepared CNx nanostructures (0.01 approximately 0.33) are strongly and systematically related to the reaction temperatures and the choice of carbon sources, as well as the presence or absence of the solvent. The Raman spectra indicate that the approaching graphitization process has occurred as the reaction temperature increases. The possible reaction mechanisms for the formation of the hollow structures are tentatively discussed according to the experimental results. This strategy provides an alternative route to synthesize nitrogen-doped carbon nanostructures and is expected to open up a new route for the synthesis of carbon nitrides.

Fe3O4 nanocrystals with novel fractal.

Fe3O4 novel fractal nanocrystals have been synthesized by a surfactant-assisted solvothermal process for the first time. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Mössbauer spectroscopy (MS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the novel fractal nanocrystals. The lengths of the fractals are about 2-3 microm, and the trunks and branches of Fe3O4 fractals have almost the same diameters of ca. 30-50 nm. The roles of surfactant PEG-20000 and N2H4 have been discussed in detail. One key fact has been found that the ferrocene concentration has a vital effect on the morphologies of the products. The side-branching process and the oscillation of the concentration have been proposed to illustrate the formation mechanisms of the fractal nanocrystals. In addition, magnetic properties of Fe3O4 fractal nanocrystals have also been detected by a vibrating sample magnetometer, showing relatively high saturation magnetization (Ms) of ca. 78.75 emu/g.