Terbium Vanadate Nanowires-Based Electrochemical Sensors for Mercury Ions.

Terbium vanadate nanowires were synthesized via a facile chemical approach using sodium vanadate and terbium chloride. Morphology, structure, composition, and electrochemical characteristics of the terbium vanadate nanowires were investigated by different techniques. Terbium vanadate nanowires with single crystalline tetragonal TbVO4 phase possess smooth surface and flat tips. The length of the nanowires is longer than 5 µm, and diameter is 40-100 nm. Terbium vanadate nanowires modified electrode was used for trace-level mercury ions (Hg2+) detection. One well-defined stripping peak exists at - 0.34 V at the terbium vanadate nanowires modified electrode in 0.1 mM Hg2+ solution. Buffer solution pH value, deposition time, deposition potential, and standing time are pH = 1, 150 s, - 1.5 V, and 60 s, respectively. Detection limit for Hg2+ detection is 0.18 nM, and linear range is 0.01-100 µM. The proposed terbium vanadate nanowires modified electrode exhibits significant selectivity, stability, and reproducibility toward Hg2+. The usefulness of the developed sensor based on the terbium vanadate nanowires modified electrode was verified by Hg2+ detection in real samples.

Controllable synthesis of BiPr composite oxide nanowires electrocatalyst for sensitive L-cysteine sensing properties.

BiPr composite oxide nanowires with rhombodedral Bi1.35Pr0.65O3, monoclinic Bi2O3and monoclinic Pr5O9phases were synthesized via a facile sodium dodecyl sulfate (SDS) assisted hydrothermal route. The obtained nanowires were characterized by x-ray diffraction, electron microscopy, x-ray photoelectron spectroscopy and electrochemical measurements. The BiPr composite oxide nanowires possess poly-crystalline structure, semi-circular tips, diameter and length of 20-100 nm and several micrometers, respectively. SDS is essential for the formation of the BiPr composite oxide nanowires which can be explained by a SDS assisted hydrothermal growth process. Electrochemical impedance spectroscopy shows that the electrons are easier to transfer by the surface of the BiPr composite oxide nanowires modified glassy carbon electrode (GCE) than bare GCE. The BiPr composite oxide nanowires modified GCE possesses good electro-catalytic activity for L-cysteine detection with a pair of quasi-reversible cyclic voltammetry peaks at +0.04 V and -0.72 V for the oxidation and reduction of L-cysteine, respectively. The roles of the scan rate, electrolyte species and L-cysteine concentration on the electrochemical responses of L-cysteine at the nanowires modified GCE were systematically analyzed. The BiPr composite oxide nanowires modified GCE presents a linear response range from 0.001 to 2 mM and detection limit of 0.27µM, good reproducibility and stability.

Synthesis of Vanadium Doped Lanthanum Bismuthate Nanorods for Enhanced Photocatalytic Activity.

Vanadium doped lanthanum bismuthate nanorods with vanadium ratio of 1%, 3%, 5% and 10 wt.% were fabricated through the hydrothermal method using sodium orthovanadate as vanadium source. Vanadium doped lanthanum bismuthate nanorod products were analyzed by scanning electron microscopy, X-ray diffraction pattern and diffuse reflection spectrum. X-ray diffraction patterns show that vanadium in the vanadium doped lanthanum bismuthate nanorods exists as triclinic Bi23V4O44.5 and monoclinic LaVO4 phases. Scanning electron microscopy observations show that the size and micro-morphology of the vanadium doped products are closely relative to the vanadium mass ratio. The length of the vanadium doped nanorods decreases and the morphology changes from nanorods to irregular nanoparticles with increasing the vanadium mass ratio. Solid UV-vis diffuse reflectance measurement shows that the bandgap value of the doped lanthanum bismuthate nanorods is narrowed from 2.37 eV to 2.25 eV after the vanadium doping ratio is increased from 1% to 10%. The doped lanthanum bismuthate nanorods illustrate enhanced photocatalytic performance for methylene orange (MO) removal with the irradiation of sunlight. The catalytic performance for MO removal depends on the irradiation time, vanadium content and dosage of the nanorods. The doped lanthanum bismuthate nanorods with the vanadium mass ratio of 10% possess the best MO catalytic degradation performance.

A Review on Ternary Bismuthate Nanoscale Materials.

BACKGROUND: Bismuth-containing nanoscale materials exhibit great application potential in catalysts, optical devices, electron devices, photo-electric devices and sensors owing to their good catalytic, optical, electric, photoelectric and sensing performance. Special research interest has been devoted to ternary bismuthate nanoscale materials due to their special layered structure, large specific surface area, excellent optical, catalytic, electrical and electrochemical performance. Therefore, it is essential to synthesize novel ternary bismuthate nanoscale materials for practical application. METHODS: The article reviews the recent progress and patents on the ternary bismuthate nanoscale materials. The recent progress and patents on the synthesis and application of the ternary bismuthate nanoscale materials are discussed. The possible development direction of the ternary bismuthate nanoscale materials for the synthesis and application is also analyzed. RESULTS: The ternary bismuthate nanoscale materials including zinc bismuthate, copper bismuthate, barium bismuthate, silver bismuthate, sodium bismuthate, lanthanum bismuthate nanoscale materials can be synthesized by hydrothermal route, sol-gel route, solvothermal decomposition route and ionexchange method. The ternary bismuthate nanoscale materials exhibit great application promising in the fields of photocatalysts, sensors and batteries. CONCLUSION: Large-scale synthesis of ternary bismuthate nanoscale materials at low cost, doping and combination using different nanoscale materials are important research directions for future research.

Electrogenerated chemiluminescence of bismuth sulfide nanorods modified electrode in alkaline aqueous solution.

Electrogenerated chemiluminescence (ECL) behavior of a bismuth sulfide nanorods modified glassy carbon electrode (NR-GCE) was investigated in alkaline aqueous solution for the first time. One weak ECL peak of the NR-GCE was observed around -1.70 V when the electrode potential was scanned from 0.0 V to -2.0 V. The intensity of the ECL peak was enhanced greatly in the presence of either H2O2 or persulfate. The dissolved oxygen, the pH and the supporting electrolytes of the working solution could influence ECL emission noticeably. Under the optimal conditions, the ECL signal displayed a good linear relationship with the concentration of hydrogen peroxide in the range of 5.0 × 10(-7) to 1.0 × 10(-4) mol L(-1) with a correlation coefficient of 0.997 and a detection limit of 2.0 × 10(-7) mol L(-1) at the signal-to-noise ratio of 3. A possible ECL mechanism of the NR-GCE was also proposed.

[The study on Raman spectra of Si nanowires].

Phonon confinement effect results in an redshift and asymmetric broadening in the low-frequency side of Raman spectra of intrinsic silicon nanowires (SiNWs), but is not the only factor impacting the Raman spectrum of SiNWs. At high incidence laser power densities, laser heating gives a redshift and symmetric broadening, and Fano interference between the scattering from the k = 0 optic phonon and the electronic continuum scattering from laser-induced carriers gives an asymmetric line shape, i. e. Fano line shape. Furthermore, due to phonon confinement effect, the fundamental k = 0 Raman selection rule is relaxed, allowing phonons away from the Brillouin zone center to participate Raman scattering too, therefore, some new weak Raman signals appear at about 604 and 423 cm(-1) in addition to the usual silicon peaks at 520, 302 and 964 cm(-1) for silicon nanowires with small diameter.