Adsorption-controlled transition of the electrical properties realized in Hematite（alpha-Fe2O3） nanorods ethanol sensing

Alpha-Fe2O3 nanorods are synthesized through a hydrothermal method with no surfactant introduced and ethanol sensors are fabricated from these nanorods.The device can respond to ethanol vapour in a concentration range from 1 to 1500 parts per million and shows both p-type and n-type responding characteristics during the investigation of the ethanol sensing.The sensor displays a p-type characteristic when the ethanol concentration is low and converted into an n-type characteristic as the concentration exceeds a certain value.Such a phenomenon is attributed to the chemisorbed oxygen,which leads to different modifications of the energy band at the surface,namely,depletion layer or inversion layer.     

Anomalous Pressure Behavior of N-Cluster Emissions in GaAs0.973Sb0.022N0.005

Photoluminescence of GaAs0.973Sb0.022N0.005 is investigated at different temperatures and pressures. Both the alloy band edge and the N-related emissions, which show different temperature and pressure dependences, are observed. The pressure coefficients obtained in the pressure range 0-1.4GPa for the band edge and N-related emissions are 67 and 45meV/GPa, respectively. The N-related emissions shift to a higher energy in the lower pressure range and then begin to redshift at about 8.5GPa. This redshift is possibly caused by the increase of the X-valley component in the N-related states with increasing pressure.     

Stable Electron Field Emission from CeO2 Nanowires by Hydrothermal Method

CeO2 nanowires are successful synthesized by hydrothermal method and their field emission （FE） properties are investigated. The turn-on electric field is 5.8 V/μm at an emitter-anode spacing of 700μm. The FE current is stable and the current fluctuations are less than 3% over 5 h. All the plotted Fowler-Nordheim curves yield straight lines, which are in agreement with the Fowler-Nordheim theory. The relationship between the field enhancement factor β and the emitter-anode spacing d follows a universal equation. Our results imply that the CeO2 nanowires are promising materials for fabricating FE cathodes.     

Klein Paradox of Two-Dimensional Dirac Electrons in Circular Well Potential

We study two-dimensional massive Dirac equation in circular well potential. The energies of bound states are obtained. We demonstrate the Klein paradox of this relativistic wave equation:For large enough potential depth, the bound states disappear from the spectra. Applications to graphene systems are discussed.     

Electro-oxidation of Formic Acid on Carbon Supported Edge-Truncated Cubic Platinum Nanoparticles Catalysts

The oxidation of formic acid on edge-truncated cubic platinum nanoparticles/C catalysts is investigated. X-ray photoelectron spectroscopy analysis indicates that the surface of edge-truncated cubic platinum nanoparticles is composed of two types of coordination sites. ＇/＇he oxidation behavior of formic acid on edge-truncated cubic platinum nanoparticles/C is investigated using cyclic voltammetry. The apparent activation energies are found to be 54.2, 55.0, 61.8, 69.5, 71.9, 69.26, 65.28k J/tool at 0.15, 0.3, 0.4, 0.5, 0.6, 0.65, 0.7V, respectively. A specific surface area activity of 1.76 mA·cm^-2 at 0.4 V indicates that the edge-truncated cubic Platinum nanoparticles are a promising anode catalyst for direct formic acid fuel cells.     

Electrodeposition of aligned ZnO sheet array on ITO substrate and their field emission characteristics

ZnO sheet array was fabricated by a simple electrodeposition method on the transparent ITO substrate at a temperature of about 60℃. The field emission properties of the ZnO sheet array were investigated. The fluctuation of the field emission current is less than 5% over several hours. The Fowler Nordheim curves with a roughly linear characteristic were obtained by analysing the current density and the intensity of the electrical field. The results prove that such a simple electrochemical method can potentially meet the demands on the production of cold cathodes for field emission display.[第一段]