Xiaoshan He

Vertically Aligned TiO2 Nanorod Arrays as a Steady Light Sensor

Vertically aligned TiO 2 nanorods have been prepared directly on Ti foil through a one-step environmentally friendly and template-free solution method. X-ray diffraction, field-emission-scanning electron microscopy, and energy-dispersive X-ray spectroscopy have been employed to characterize the synthesized samples. The control of morphology and size of the TiO 2 nanorods can be achieved by varying the solution concentration, hydrothermal temperature, and synthesis time. The influence of nanorod size on the conductivity has been investigated by electrochemical impedance spectroscopy, and the results indicate that the electrical conductivity of thin nanorod arrays is better than that of thick nanorod arrays. Meanwhile, the electrode based on the thin nanorod arrays has shown a highly sensitive and steady photocurrent response under simulated sunlight and UV illumination, which indicates that the nanorod TiO 2 arrays could be a candidate for use in optoelectronic sensor.

Glassy State Lead Tellurite Nanobelts: Synthesis and Properties

The lead tellurite nanobelts have been first synthesized in the composite molten salts (KNO3/LiNO3) method, which is cost-effective, one-step, easy to control, and performed at low-temperature and in ambient atmosphere. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrum, energy dispersive X-ray spectroscopy and FT-IR spectrum are used to characterize the structure, morphology, and composition of the samples. The results show that the as-synthesized products are amorphous and glassy nanobelts with widths of 200–300 nm and lengths up to tens of microns and the atomic ratio of Pb:Te:O is close to 1:1.5:4. Thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) and investigations of the corresponding structure and morphology change confirm that the nanobelts have low glass transition temperature and thermal stability. Optical diffuse reflectance spectrum indicates that the lead tellurite nanobelts have two optical gaps at ca. 3.72 eV and 4.12 eV. Photoluminescence (PL) spectrum and fluorescence imaging of the products exhibit a blue emission (round 480 nm).

Enhancement of Electrochemical Differentiation Ability of Nucleobases in Phosphate Buffer Solution at pH 7.4

The electrochemical behavior of nucleobases has been studied in 0.1 M phosphate buffer solution at pH 7.4, using a bare graphite electrode. Guanine and adenine produced well-defined oxidation peaks at about +0.63 and +0.91 V at 100 mV/s, respectively. Nucleobases exhibit an irreversible and hybrid-controlled electrochemical process, including adsorption and diffusion. The nucleobase oxidation peaks shift due to the selective interactions of nucleobases with each other. The oxidation peaks for three different pyrimidine bases, uracil, cytosine, and thymine, can be clearly identified at +1.26, +1.41, and +1.32 V, respectively. These differences in the electrochemical behavior among nucleobases can be attributed to their different chemical structures.

Magnetic and optical properties of Mn doped ZnO nanocrystalline films

We have investigated the properties of Mn-doped ZnO nanocrystalline films grown on zinc foil by hydrothermal method. The microstructure, optical and magnetic properties of these films have been characterized by SEM, XRD, XPS and UV-vis spectrum. The XPS spectra show the doping manganese exists as Mn2+. From UV-vis spectra, the shift in band gap and greater reflectivity can be observed due to Mn doping in ZnO. The magnetic property measurement of the Mn-doped ZnO exhibits a room temperature ferromagnetic characteristic with a saturation magnetization (Ms) of 0.3902×10−3 emu/cm2 and a coercive field of 47 Oe.

Synthesis of functional carbon nanospheres and amperometric sensing of hydrogen peroxide

Functional carbon nanospheres have been synthesized from analytically pure glucose by a composite-molten-salt (CMS) method. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman and Fourier transformation infra-red (FTIR) spectroscopy indicate the carbon nanospheres are solid, bond hybridisation (sp2/sp3) and with many functional groups on their surfaces. Amperometric sensor based on the synthesized carbon nanospheres has been fabricated without pretreatment or modification. The detection of hydrogen peroxide exhibits high sensitivity, good selectivity and excellent reproducibility. The electrochemical measurement of these nanospheres demonstrates much superior performance to those of the carbon nanospheres synthesized by hydrothermal method.