Search results for "Cathode"
showing 10 items of 296 documents
Air stable hybrid organic-inorganic light emitting diodes using ZnO as the cathode
2007
An air stable hybrid organic-inorganic light emitting device is presented. This architecture makes use of metal oxides as charge injecting materials into the light emitting polymer, avoiding the use of air sensitive cathodes commonly employed in organic light emitting diode manufacturing. We report the application of zinc oxide as a cathode in an organic light emitting device. This electroluminescent device shows high brightness levels reaching 6500 cd/m2 at voltages as low as 8 V. Compared to a conventional device using low workfunction metal cathodes, our device shows a lower turn-on voltage and it can operate in air.
Development of a 3D CZT detector prototype for Laue Lens telescope
2010
We report on the development of a 3D position sensitive prototype suitable as focal plane detector for Laue lens telescope. The basic sensitive unit is a drift strip detector based on a CZT crystal, (similar to 19x8 mm(2) area, 2.4 mm thick), irradiated transversally to the electric field direction. The anode side is segmented in 64 strips, that divide the crystal in 8 independent sensor (pixel), each composed by one collecting strip and 7 (one in common) adjacent drift strips. The drift strips are biased by a voltage divider, whereas the anode strips are held at ground. Furthermore, the cathode is divided in 4 horizontal strips for the reconstruction of the third interaction position coord…
Toward Three-Dimensional Chemical Imaging of Ternary Cu–Sn–Pb Alloys Using Femtosecond Laser Ablation/Ionization Mass Spectrometry
2017
Femtosecond laser ablation/ionization mass spectrometry (LIMS) has been applied to probe the spatial element composition of three ternary Cu-Sn-Pb model bronze alloys (lead bronzes: CuSn10Pb10, CuSn7Pb15, and CuSn5Pb20), which were recently identified as high-performance cathode materials in the context of electro-organic synthesis (dehalogenation, deoxygenation) of pharmaceutically relevant building blocks. The quantitative and spatially resolved element analysis of such cathode materials will help in understanding the observed profound differences in their electrochemical reactivity and stability. For that purpose, we developed a measurement procedure using the LIMS technique which allows…
From Screening to Scale-Up: The DoE-Based Optimization of Electrochemical Reduction of l-Cystine at Metal Cathodes
2021
Design of experiment (DoE) is a powerful statistical tool in establishing improved chemical processes. An optimization and scale-up of the electrochemical reduction of l-cystine to l-cysteine is pr...
Stabilizing Lead Cathodes with Diammonium Salt Additives in the Deoxygenation of Aromatic Amides
2014
Lead is efficiently protected against cathodic corrosion by the addition of diammonium salts in the electrolyte. The cationic coating of the cathode allows the efficient electroreduction of benzamides to benzylamines. The electrochemical deoxygenation of the amide is achieved without the use of oxophilic agents or sacrificial anodes. The surface of the lead cathode stays smooth and the cathode can be reused for multiple runs, providing <2.5 ppm of the crude product. Cyclic voltammetry studies reveal a shift in the onset potential of the hydrogen evolution reaction by −157 mV.
Electrocarboxylation of benzyl chlorides at silver cathode at the preparative scale level
2008
Abstract The electrocarboxylation of benzyl chlorides to the corresponding carboxylic acids performed at silver cathodes was investigated both theoretically and experimentally in order to find the influence of the operative parameters on the selectivity and on the Faradic efficiency of the process. Theoretical considerations were confirmed by the electrocarboxylation of 1-phenyl-1-chloroethane performed in undivided cells equipped with sacrificial anodes both in a bench-scale electrochemical batch reactor and in a continuous batch recirculation reaction system equipped with a parallel plate electrochemical cell. Selectivity and Faradic yields higher than 80% and 70%, respectively, were obta…
Morphological, electrical and optical properties of organic light-emitting diodes with a LiF/Al cathode and an Al-hydroxyquinoline/diamine junction
2004
Abstract We report the results of the morphological, electrical and optical characterisation of double-layer Alq3-based organic emitting diodes with a lithium fluoride (LiF)/Al cathode. A detailed electron microscopy investigation of their cross-section shows the presence of LiF isolated grains underneath the Al film. Due to the introduction of the LiF layer, luminance was larger than 30,000 cd/m2 at a bias voltage VB=25 V with a maximum external luminous efficiency as large as 46 lm/W at VB=20 V. Performing on/off VB cycles at a very low frequency, each time a recovery of the initial electric and luminous performance was observed. The non-exponential decay of both electric current and lumi…
Combined theoretical and experimental analysis of processes determining cathode performance in solid oxide fuel cells
2013
Solid oxide fuel cells (SOFC) are under intensive investigation since the 1980's as these devices open the way for ecologically clean direct conversion of the chemical energy into electricity, avoiding the efficiency limitation by Carnot's cycle for thermochemical conversion. However, the practical development of SOFC faces a number of unresolved fundamental problems, in particular concerning the kinetics of the electrode reactions, especially oxygen reduction reaction. We review recent experimental and theoretical achievements in the current understanding of the cathode performance by exploring and comparing mostly three materials: (La,Sr)MnO3 (LSM), (La,Sr)(Co,Fe)O3 (LSCF) and (Ba,Sr)(Co,…
Electrochemical Synthesis of d,l-Homocysteine Thiolactone Hydrochloride in a Batch Continuous Recirculation Reactor Equipped with Carbon Felt Cathode…
2007
The electrochemical reduction of D,L-homocystine hydrochloride to the corresponding cysteine was performed in a batch continuous recirculation reaction system that was equipped with a FM01-LC electrochemical reactor. Electrolyses were performed under amperostatic conditions, using carbon felt cathodes and DSA anodes divided by Nafion 324 cationic membranes. A simple reactor mathematical model was used to assess the effect of operative parameters (the initial substrate concentration, the reaction temperature, the current density, and the linear velocity of the catholyte) on the performances of the process, with the objective of determining the optimized conditions to perform the electrosynth…
New method to determine the true transmissibilities and permeabilities of oxygen in hydrogel membranes
1999
In the present paper, an electrochemical method to obtain the true transmissibilities and permeabilities of hydrogels to oxygen is proposed. The method involves the measurement of the electric current arising from the flow of oxygen through a potentiostat cell integrated by a top water layer, the hydrogel membrane, and a thin water layer between the membrane and the cathode, where the oxygen is reduced. Varying the thickness of the top water layer, the true permeation characteristics of the hydrogels are obtained. A parallel study was carried out in which the transmissibilities and permeation coefficients were obtained from the variation of the steady state current with the thickness of the…