Search results for "Cathode"
showing 10 items of 296 documents
The modelling of the cathode sheath of an electrical arc in vacuum
2003
This paper presents a simple model of the fragment in the cathode electrical arc root taking into account the physical phenomena occuring on the cathode surface and the sheath. The goal is the obtainment of characteristics values of the heat flux, the electrons, and atoms density in the sheath. Computation is carried out on a one-dimensional model with a coupling between the equation obtained in the sheath and an enthalpy model of the cathode to describe the temperature evolution. In the modelling, we introduce a friction zone above the sheath edge to characterize the heavy particle interactions. Numerical simulation shows that the ionic friction phenomenon deriving from ion–atom collision …
An improved cathode for alkaline fuel cells
2010
Abstract The use of nickel foam as an electrode substrate in alkaline fuel cells (AFCs) has been investigated for bipolar cells incorporating an electrically conducting gas diffusion layer (GDL). Improved performance, compared to a previous design, was obtained by adding an extra active layer (AL) composed of manganese (IV) oxide (MnO2) deposited onto carbon black. This new cathode design performed significantly better (130 mA cm−2 at 0.8 V and 25 °C) than the previous design (35 mA cm−2 under the same condition), especially at higher potential. It has been shown that the GDL is a key component of the gas diffusion electrode for both performance and durability, especially with liquid electr…
Transient and stable color centers in pure and Cu-doped LiNbO3
2003
The present work is devoted to investigation of stable and transient color centers that are induced by radiation and temperature in pure and Cu-doped LiNbO 3 single crystals. The transient changes of absorption of the crystals induced by pulsed electron beam (E=0.25 MeV) are studied in 0-5000 ns time range, as well as stable changes of absorption induced by reducing annealing and irradiation with γ-quanta, high energy electrons or fast reactor neutrons.
Electrochemical conversion of pressurized CO2 at simple silver-based cathodes in undivided cells: study of the effect of pressure and other operative…
2020
Abstract Electrochemical reduction of pressurized CO2 is proposed as an interesting approach to overcome the main hurdle of the CO2 electrochemical conversion in aqueous solution, its low solubility (ca. 0.033 M), and to achieve good faradaic efficiency in CO using simple sheet silver cathodes and undivided cells, thus lowering the overall costs of the process. The effect on the process of CO2 pressure (1–30 bar), current density, nature of the supporting electrolyte and other operative conditions, such as the surface of the cathode or the mixing rate, was studied to enhance the production of CO. It was shown that pressurized conditions allow to improve drastically the current efficiency o…
Nano photoelectron ioniser chip using LaB6 for ambient pressure trace gas detection
2012
A detector including a nanoscaled ioniser chip that surmounts the limitation of conventional photo ionisation detectors is presented. Here, ionisable gaseous substances can be detected by photoelectrons accelerated to the ionisation potential of the incoming gaseous molecules. Thin lanthanum hexaboride (LaB"6) films deposited by pulsed laser technique (PLD) serve as the air stable photocathode material representing the basis of the ioniser chip of the detector. Besides the analysis of the emission behaviour of the photocathode in vacuum and at atmospheric pressure, the detection of different volatile alcohols using the detector with a low-energy UV LED instead of a PID (VUV photon source) w…
Initial chemical transport of reducing elements and chemical reactions in oxide cathode base metal
2002
Abstract In the present work, the formation of compounds associated to the diffusion of reducing elements (Mg and Al) to the nickel surface of a one-piece oxide cathode has been studied. Those compounds have been evidenced after the annealing steps at high temperature performed on cathode base metal prior to the emitting coating deposition. Therefore, they form the “initial” interface between the nickel and the coating, in other words, the interface existing at the beginning of cathode life. Extensive analysis to characterize the nickel base prior to coating deposition has been performed by means of scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), …
High-performing Sn-Co nanowire electrodes as anodes for lithium-ion batteries
2012
Abstract The preparation of Sn 2 Co 3 nanowire arrays (NWs) electrogrown inside the channels of polycarbonate membranes and their characterization as anodes for Li-ion batteries both in half-cell vs. Li and in battery configuration are reported. The Sn 2 Co 3 NW electrodes tested by deep galvanostatic charge/discharge cycles in ethylene carbonate-dimethylcarbonate (1:1) – LiPF 6 1 M displayed 80% capacity retention after 200 cycles at C/2 and 30 °C, and a high charge and discharge rate capability at C-rate from C/3 (0.33 A/g) to 10C (10 A/g) at 30° and 10 °C. Electrodes with the highest alloy loading delivered up to 0.6 mAh cm −2 at C/2. The performance of these electrodes in battery config…
Metal Oxides for Rechargeable Batteries Energy Applications
2020
Nearly three decades of significant academic and commercialization progress, appreciations have to be credited for Li+ ion-based rechargeable secondary batteries, which conquered the entire world. The Li+ ion batteries dictate the consumer battery market and are considered crucial for the practical realization of plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and electric vehicles (EVs). Recently, post-lithium–ion batteries, particularly Na, K, Mg, and Zn, and Al–ion batteries have also been intensively explored for various energy storage tenders due to their natural abundance, low cost, and environmental safety of these materials. The utilization of metal oxides…
Enhanced Electrochemical Properties of Na0.67MnO2 Cathode for Na-Ion Batteries Prepared with Novel Tetrabutylammonium Alginate Binder
2022
This research was funded by the State Education Development Agency, the Republic of Latvia, grant number 1.1.1.2/VIAA/1/16/166, "Advanced Materials for Sodium-Ion Batteries". Institute of Solid-State Physics, University of Latvia as the Centre of Excellence has received funding from the European Union's Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.
Monofunctional pyrenes at carbon nanotube electrodes for direct electron transfer H2O2 reduction with HRP and HRP-bacterial nanocellulose
2021
Abstract The non-covalent modification of carbon nanotube electrodes with pyrene derivatives is a versatile approach to enhance the electrical wiring of enzymes for biosensors and biofuel cells. We report here a comparative study of five pyrene derivatives adsorbed at multi-walled carbon nanotube electrodes to shed light on their ability to promote direct electron transfer with horseradish peroxidase (HRP) for H2O2 reduction. In all cases, pyrene-modified electrodes enhanced catalytic reduction compared to the unmodified electrodes. The pyrene N-hydroxysuccinimide (NHS) ester derivative provided access to the highest catalytic current of 1.4 mA cm−2 at 6 mmol L−1 H2O2, high onset potential …