Ultrahigh power factor and enhanced thermoelectric performance of individual Te/TiS2 nanocables.

Here, we present the successful fabrication of Te/TiS2 heterostructure nanocables with enhanced thermoelectric (TE) performance by a two-step route (a facile solvothermal approach for Te nanowires and then the Te nanowires are used as templates for the controllable growth of the Te/TiS2 nanocables), which is scalable for practical nanodevice applications. The heterostructure nanocables of different sizes can be prepared by varying the synthetic composition. Measurements of the Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ) are carried out on the same nanowires over a temperature range of 2-350 K. The heterostructure nanocables show an ultrahigh power factor (S(2) σ) with a maximum value of 0.58 Wm(-1) K(-2), which comes from a high electrical conductivity and a strongly enhanced Seebeck coefficient. The figure of merit (ZT) can reach 1.91 at room temperature from a single nanocable with a diameter of 60 nm, which is thought to contribute to the formation of the hetero-phase core/shell structure. These results are expected to open up new application possibilities in nanoscale TE devices based on individual Te/TiS2 heterostructure nanocables.

Facile and economical synthesis of large hollow ferrites and their applications in adsorption for As(V) and Cr(VI).

Unlike the previous ferrites (MFe2O4; M=Fe, Co, Zn, and Mn) solid nanospheres/nanoparticles, which were prepared by polluted solvothermal (glycol) approaches, here controllable monodisperse porous ferrites hollow nanospheres are promptly synthesized by a nontemplate hydrothermal method which has introduced an addition agent, polyacrylamide. The hollow nanospheres with different size can be prepared by varying the synthetic compositions. Scanning/transmission micros-graphs show the outside diameters of ferrite nanospheres are 180-380 nm and the shell thicknesses of that are only 20-45 nm, which could be adjusted by controlling CH3COONa concentration. X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy, scanning electron (SEM) and transmission electron (TEM) microscopy, energy-dispersive spectrometer (EDS), the measurement of N2 adsorption-desorption isotherms and Brunauer-Emmett-Teller (BET) surface area, and superconducting quantum interference device (SQID) magnetometer were adopted to analyze their phase composition, morphology, porosity, and magnetic properties, respectively. The results of controlled experiments show that citrate and polyacrylamide are vital for the phase purities and morphology of ferrites. In particular, the as-obtained samples exhibit a large adsorption capacity for the toxic solution containing As(V) and Cr(VI) ions, and the calculated result of the maximum adsorption capacity is 340 mg/g based on Langmuir model, which shows excellent As(V) and Cr(VI) ions uptake capacity in contrast to other solid nanosphere materials.

Controlled synthesis of homogeneous Ag nanosheet-assembled film for effective SERS substrate.

Homogeneous Ag nanosheet-assembled film was successfully fabricated by using Cu plate through a simple modified solution method, where weak reductive Cu2O layer and complexing agent citrate ions were both introduced into the reaction system to control the reaction process. Meanwhile, citrate ions were used as morphology-controlled reagent to lead Ag units to grow in the form of nanosheet. The growth process exhibited that Ag nanosheet-assembled film formed slowly with reaction proceeding. Additionally, the pack density of nanosheets in the final product was found to be adjusted by the concentrations of Ag(+) ions in precursor solution. Using Rhodamine 6G (R6G) as probing molecules, the surface-enhanced Raman scattering (SERS) experiments showed that the Ag film assembled by nanosheets with high pack density exhibited excellent detecting performance, which could be used as effective SERS substrate for ultrasensitive detecting. Besides, a novel quintuplet SERS substrate could be synthesized in one batch by our method, which showed good reproducibility and a linear dependence between analyte concentrations and intensities, revealing the advantage of this method for easily scale-up production.