Search results for " IMPEDANCE SPECTROSCOPY"

The origin of slow electron recombination processes in dye-sensitized solar cells with alumina barrier coatings

2004

We investigate the effect of a thin alumina coating of nanocrystalline TiO2 films on recombination dynamics of dye-sensitized solar cells. Both coated and uncoated cells were measured by a combination of techniques: transient absorption spectroscopy, electrochemical impedance spectroscopy, and open-circuit voltage decay. It is found that the alumina barrier reduces the recombination of photoinjected electrons to both dye cations and the oxidized redox couple. It is proposed that this observed retardation can be attributed primarily to two effects: almost complete passivation of surface trap states in TiO2 that are able to inject electrons to acceptor species, and slowing down by a factor of…

MCM-41 silica effect on gel polymer electrolytes based on thermoplastic polyurethane

2012

Abstract Polymer electrolytes were prepared from thermoplastic polyurethane with addition of mixture of N-ethyl(methylether)-N-methylpyrrolidinium trifluoromethanesulfonimide (PYRA12O1TFSI) ionic liquid, lithium bis(trifluoromethanesulfoneimide) salt and propylene carbonate. MCM-41 mesoporous silica was added in proportions ranging from 5 to 20 wt.% with respect to TPU. The electrolytes were characterized by thermogravimetric analysis, differential scanning calorimetry, linear voltammetry and impedance spectroscopy. The MCM-41 addition to the system was found to improve the electrochemical stability of the membranes and to reduce the gel electrolyte/metallic Li interfacial resistance. The f…

Conductive and Capacitive Properties of the Bipolar Membrane Junction Studied by AC Impedance Spectroscopy

2001

The complete ac impedance spectrum of four bipolar membranes is analyzed both theoretically and experimentally taking into account both ionic transport and water dissociation together with the structural aspects of the bipolar junction. A theoretical model based on the Nernst-Planck and Poisson equations for the conductive and capacitive properties of the junction provides a qualitative description of the bipolar membranes for a broad range of electric currents and temperatures. Special attention is paid to the characteristics of the bipolar junction structure and the contact region between the two ion-exchange layers. It is observed that the effective area of this region increases with the…

Analysis of adsorption of phospholipids at the 1,2-dichloroethane/water interface by electrochemical impedance spectroscopy: A study of the effect of…

2007

Abstract The adsorption behaviour of a series of phosphatidylcholines (PCs) with saturated carbon chains of different length (DLPC, DPPC, DSPC, DAPC, and DBPC) at the electrified 1,2-dichloroethane/water interface was studied by measuring electrochemical impedance spectroscopy at the polarized interface. Two different trends in the interfacial capacitance were observed for any of the PCs the capacity dependence on the applied potential: strong adsorption occurs at negative potential with a marked decrease of C ( E ); increase of capacity is observed at positive potentials. It is demonstrated that the interfacial lipid adsorption was dependent on phospholipid concentration, applied potential…

PBI-based composite membranes for polymer fuel cells

2010

Abstract In the present study poly(2,2-(2,6-pyridin)-5,5-bibenzimidazole) was used for the preparation of novel MEAs for high-temperature polymer fuel cells (HT-PEMFCs). We prepared hybrid materials with two types of silica fillers in order to increase the MEA performances using this polymer. The membranes were characterized in terms of their microstructure and thermal stability. Cell operation tests and Electrochemical Impedance Spectroscopy were used for the characterization of the MEAs. A maximum power density of about 80 mW cm−2 was obtained at 300 mA cm−2 by using an imidazole-modified silica filler. The EIS technique showed that the fillers chiefly help to reduce the charge transfer r…

Influence of post formation proceses on electrochemical and photoelectrochemical behaviour of TiO2 nanotubes

2011

Morphology Influence on Wettability and Wetting Dynamics of ZnO Nanostructure Arrays

2022

This study has been supported by internal research grant No. 14-95/2021/10 of Daugavpils University “Development of the Nanostructured Metal Oxide Coatings and Their Application in Optical Sensing for Heavy Metal Detection”.

Activation of Stainless Steel 316L Anode for Anion Exchange Membrane Water Electrolysis

2023

The increased emphasis on renewable energy has resulted in a surge of R&D efforts into hydrogen and battery research. The intensive electrochemical environment surrounding the anodic oxygen evolution reaction (OER) has plagued both the activity and stability of the catalytic layer, substrate and porous transport layer, ultimately affecting both these industries. Herein, we report the benefits of potential cycling (PC) a 316L stainless steel felt porous transport layer (PTL) for use in anion exchange membrane water electrolysis. The PC increased surface roughness and created a CrFe5Ni2-OxHy layer through the oxidation of iron as shown by SEM, EDS, XPS, XRD and Raman spectroscopy. Post-PC tes…