Search results for "Anode"

Mass‐Spectrometric Imaging of Electrode Surfaces—a View on Electrochemical Side Reactions

2020

Abstract Electrochemical side reactions, often referred to as “electrode fouling”, are known to be a major challenge in electro‐organic synthesis and the functionality of modern batteries. Often, polymerization of one or more components is observed. When reaching their limit of solubility, those polymers tend to adsorb on the surface of the electrode, resulting in a passivation of the respective electrode area, which may impact electrochemical performance. Here, matrix‐assisted laser‐desorption/ionization mass spectrometry (MALDI‐MS) is presented as valuable imaging technique to visualize polymer deposition on electrode surfaces. Oligomer size distribution and its dependency on the contact …

Front Cover: Metal‐ and Reagent‐Free Anodic Dehydrogenative Cross‐Coupling of Naphthylamines with Phenols (ChemElectroChem 9/2018)

2018

Heat and mass transfer analysis in single cell of PEFC using different PEM and GDL at higher temperature

2019

Abstract According to the H2 and fuel cell road map in Japan, the target operating temperature of polymer electrolyte fuel cell (PEFC) should be 90 °C from 2020 to 2025. In this study, the impact of polymer electrolyte membrane (PEM) and gas diffusion layer (GDL)'s thickness on heat and mass transfer characteristics as well as power generation performance of PEFC is investigated at operating temperature of 90 °C. The in-plane temperature distributions on anode and cathode separator are also measured using thermograph. As a result, it is observed that the increase in power from 1 W to 5 W at the current density of 0.80 A/cm2 as well as even temperature distribution within 1 °C can be obtaine…

Growth and Characterization of Anodic Films on Scandium

2013

The anodic behavior of Sc in a slightly alkaline aqueous solution is studied. Electrochemical and capacitance measurements suggest that passive films can be formed on the scandium surface under a high electric field. The formation of these layers occurs at low faradaic efficiency due to oxygen evolution. Photoelectrochemical experiments suggest the formation of a barrier layer with a thickness high enough to hinder external electron photoemission processes and allow the estimation of the bandgap of the films as a function of their formation voltage. The estimated bandgap values were lower than that reported for Sc2O3, suggesting the formation of hydrated phases and/or of a strongly oxygen d…

Growth and Characterization of Ordered PbO[sub 2] Nanowire Arrays

2008

Large arrays of PbO 2 nanowires having high aspect ratios (length-to-width ratio) were grown by potentiostatic electrodeposition into anodic alumina templates under anodic polarization. Different electrolytic solutions were used in order to obtain nanowires of pure α-PbO 2 , pure β-PbO 2 , and a a + β mixture, We have found that, in a lead nitrate bath, a crystallographic structure of nanowires depends on pH; this latter was varied adding diluted nitric acid to the electrolyte. Nanowires of pure β-PbO 2 were obtained at pH 0.6, while mixed α-PbO 2 + β-PbΟ 2 nanowires were grown at pH 2. Pure α-phase was obtained in a bath containing lead acetate at pH 6.6. In all deposition conditions, nano…

Development of a 3D CZT Spectrometer System with Digital Readout for Hard X/Gamma-Ray Astronomy

2019

We report on the development and of a complete X/γ rays detection system (10-1000 keV) based on CZT spectrometers with spatial resolution in three dimensions (3D) and a digital electronics acquisition chain. The prototype is made by packing four linear modules, each composed of one 3D CZT sensors. Each sensors is realized using a single spectroscopic graded CZT crystal of about 20×20×5 mm3. An electrode structure consisting of 12 collecting anodes with a pitch of 1.6 mm and 3 drift strips between each pair of anodes for 48 strips (0.15 mm wide) on the anodic side was adopted. The cathode is made of 10 strips with a pitch of 2 mm and orthogonal to anode side strips. Since the reading of the …

Characterization of Sn-Co nanowires grown into alumina template

2009

Nanowires of Sn-Co alloys were grown inside the channels of anodic alumina membrane by potentiostatic deposition. The scanning electron microscope images showed the formation of cylindrical nanowires whose height was increasing with deposition time. The X-ray patterns did not show significant diffraction peaks, suggesting the formation of amorphous phases. The higher content of Co in the nanowires, in comparison to the initial composition of the electrolytic bath, was attributed to a higher rate of Co electrodeposition. These nanowires seem to possess specific features suitable for innovative application in the field of Li-ion batteries due to their dimensional stability and high specific s…

Characterization of the Solid State Properties of Anodic Oxides on Ta-Nb Alloys as a Function of the Anodizing Conditions

2011

Tantalum oxide, niobium oxide and Ta-Nb containing mixed oxides were grown by anodizing sputter-deposited TaxNb(1-x) alloys with 0 ≤ x ≤ 1. A photoelectrochemical investigation was performed in order to estimate the band gap values of the oxides as a function of their composition as well as to estimate their flat band potential. Differential capacitance curves were recorded for all the investigated oxides in a wide range of electrode potential and for several frequencies of the alternative signal. The dependence of C on the applied potential and a.c. frequency was interpreted on the basis of amorphous semiconductor Schottky barrier, and allowed to estimate the dielectric constant of the inv…

The Effect of Nb Incorporation on the Electronic Properties of Anodic HfO2

2017

Hafnium oxide and Nb doped HfO2 were grown by anodizing sputtering-deposited Hf and Hf-4at.%Nb. Photoelectrochemical characterization was carried out in order to estimate solid state properties such as band gap, flat band potential and electrons internal photoemission threshold energy as a function of thickness and composition of anodic oxides. Optical transitions at energy lower than the band gap value of the investigated anodic films were evidenced, and they are attributed to optical transitions involving localized states inside the band gap. Such states were located at 3.6 eV and 3.9 eV below the conduction band edge for the Nb free and Nb containing hafnium oxide, respectively. Impedanc…

Observation of New Oscillatory Phenomena during the Electrochemical Anodization of Silicon

1999

This paper reports the observation of large undamped voltage oscillations during the anodic polarization of silicon in electrol yte containing a combination of acids. One of them stimulates oxide growth and the other its chemical dissolution (in the present c ase, (0.01-0.1 M H3PO4) + (0.001- 0.01 M HF). This temporal patterning of the anodization process is shown to be due to the formation of a thin (50-90 nm) oxide layer at the sample surface and its subsequent lifting-off. The mechanism of oxide detachment i s thought to be an isotropic growth of micropores at the oxide/silicon interface triggered on by changes of electrochemical condi tions there.