Search results for "Nb2O5"

The Influence of Thermal Treatment on the Electronic Properties of a-Nb2O5

2009

The effect of thermal treatments for 1h at 250{degree sign}C in air or under vacuum on the electronic structure of thick amorphous anodic niobia was characterized by electrochemical impedance, differential admittance (DA) and photocurrent spectroscopy (PCS). The analysis of anodized niobia has revealed that it behaves as a pure dielectric. The thermal treatment in air increases the value of the differential capacitance of the niobia sample. The effect is stronger when the thermal treatment is carried out in vacuum and can be cancelled out by reanodizing the oxide to the initial formation potential. In the case of thermally vacuum-treated sample, a behavior typical of semiconducting amorphou…

Physicochemical characterisation of thermally aged anodic films on magnetron sputtered niobium

2010

The influence of thermal aging, at intermediate temperature (1h at 250°C) and in different environments, on the electronic and solid-state properties of stabilized 160 nm thick amorphous anodic niobia, grown on magnetron sputtered niobium metal, has been studied. A detailed physicochemical characterisation of the a-Nb2O5/0.5M H2SO4 electrolyte junction has been carried out by means of photocurrent and electrochemical impedance spectroscopy as well by differential admittance measurements. A change in the optical band gap (3.45 eV) of niobia film has been observed after aging (3.30 eV) at 250°C in air for 1 hour. A cathodic shift (0.15-0.2 Volt) in the flat band potential of the junction has …

Photoelectrochemical Synthesis of Conducting Polymers on Large Band Gap Nb2O5 and Ta2O5 Anodic Oxide Films

2008

Influence of film thickness and amorphous nature on the differential capacitance measurements of a-Nb2O5/electrolyte junction

2011

Modeling of differential admittance behaviour of thin amorphous semiconducting film

2012

The understanding of the electronic properties of thin oxide film is an important step toward the understanding of the mechanisms of film dissolution and breakdown as well as for their application in the field of electrolytic capacitors and solar energy conversion. From this point of view the correct location of the characteristic energy levels (flat band potential, Ufb, and conduction (valence) band edge EC (EV)), of a passive film/electrolyte junction is the preliminary task for a deeper understanding of the mechanism of charge transfer at oxide/electrolyte interface. At this aim the most frequently employed method to locate such characteristic energy levels of semiconductor oxide/electro…

Photocatalytic Generation of H2 by Photoreforming of Organics in Aqueous Suspension of Nb2o5/C3n4 Composites

2023

Bare and composite materials based on C3N4 and Nb2O5 have been used as photocatalysts for the photoreforming of aqueous solutions of oxygenated compounds. Both Nb2O5 and Nb2O5/C3N4 composites have been prepared by hydrothermal synthesis and all of them were physical-chemically characterized. In this work two different carbon nitride species i.e. graphitic (g-C3N4) or thermo-etched (TE-C3N4) were used both alone or coupled with Nb2O5. The photo-reforming activity has been measured under UV irradiation by using the semiconductors in the presence of Pt as co-catalysts and, in the case of the best material, it was, for the first time, measured and compared also under natural solar irradiation. …