1,721,055 research outputs found
Stable films of zinc-hexacyanoferrate: electrochemistry and ion insertion capabilities
Full text linkA stable film of zinc hexacyanoferrate is deposited on a GC (glassy carbon) substrate following a specific electrochemical protocol. The electrode maintains its characteristic even after dry and wet processes. SEM characterization confirms the cubic morphology of the materials and the IR suggests the presence of the FeII-C-N-ZnII structural unit. The electrochemical characterization indicates a very good stability of the film, thus opening application in ion exchange system. The focus is on monovalent, divalent, and trivalent ions. These results, the zinc low toxicity, and cost make zinc hexacyanoferrate films a promising candidate for many electrochemical applications
Physico-chemical approaches in materials investigations
No full textPhysico-chemical characterization is the keystone to fully understand the material properties. This topical issue has collected almost 30 contributions reflecting the latest developments on the topic. It includes, but is not limited to spectroscopic characterization, characterisation of materials by using neutrons as source, development of alternative synthetic routes of nanoparticles, microwave assisted synthesis, preparation of polymeric nanocomposites, archaeometric investigation of ancient materials
Absorption of polarized X-rays by V2O5-based cathodes for lithium batteries: An application
No full textVanadium pentoxide materials prepared through sol-gel processes (xerogel, aerogel and aerogel-like) act as excellent intercalation hosts for lithium as well as for polyvalent cations. The large lithium insertion capacity of these materials makes them attractive for use as cathodes in high capacity lithium batteries. This paper describes the utility of X-Ray absorption spectroscopy (XAS) for the investigation of gel-based V2O5 materials. In particular, X-ray near edge structure (XANES) and polarized EXAFS experiments are highlighted. © 2002 Elsevier Science Ltd. All rights reserved
Comparative electrochemical behavior of Prussian blue analogues as a host electrode for rare earth element recovery
Full text linkIn this paper, electrodeposited films belonging to the Prussian Blue Analogues (PBAs) family, namely, nickel-hexacyanoferrate (NiHCF) and copper-hexacyanoferrate (CuHCF), were employed as a host material for rare earth elements (REE), and the reported insertion/release study reveals a recovery capability for such valuable metals. The ion insertion/release was accomplished by adopting an electrochemically-driven process. A reversible intercalation was observed while considering both heavy and ligth rare earth elements. The amount of REEs inserted/released over the process and its kinetic evolution during the process were also studied by a chemometric approach. For CuHCF, it was seen that the intercalation of heavy rare earth elements occurs easily respect to the light ones, suggesting a possible selectivity among these ions
In situ X-ray absorption studies of the electrochemical reduction of hydroxoeobalamin
No full textXAS fluorescence is combined with electrochemical technique to study the reduction of hydroxocobalamin ( OH-Co(III)Cbl ) to cob(II)alamin at the cobalt K-edge. The electrochemical control permits to select a well-defined cobalt oxidation states. The experimental set-up used permits in situ reactions allowing reliable comparison among XANES spectra. The absorption edge shifts to lower energy with the progressive reduction of cobalt. The size of the peak at about 7726 eV (A peak) decrease in Co(H)cbl spectrum. Experimental XANES of OH-Co(III)cbl and Co(II)cbl were simulated by multiple scattering theory. Theoretical and experimental data are in agreement, peak intensity being correlated to the coordination number confirming that cobalt is five coordinate in Co(II)Cbl sample
Identification of an unconventional zinc coordination site in anhydrous ZnxV2O5 aerogels from x-ray absorption spectroscopy
No full textV2O5 aerogel (ARG) has been studied as an insertion host for lithium ions and for several polyvalent cations. The stability, reversibility, and capacity for ion insertion and release processes make the amorphous ARG an interesting material for battery applications. The local structural modifications resulting from the chemical insertion of Zn2+ ions into the host have been investigated by X-ray absorption spectroscopy (XAS). X-ray absorption nearedge structure (XANES) spectra at the V K-edge of ZnxV2O5 did not shown any substantive change as a function of increasing amounts of intercalated ions, thus indicating the absence of interactions between the intercalated ions and the vanadium ions. To study the structural sites of the polyvalent ions, EXAFS (extended X-ray absorption fine structure) spectra have been recorded at the Zn K-edge. The EXAFS analysis showed that the Zn2+ ions are 4-fold coordinated by almost coplanar oxygens. In addition, differences in the first shell of the inserted Zn2+ as a function of the intercalation level have been observed. The first-shell Zn-O bond length shortened and the EXAFS Debye-Waller factor increased. This suggests a decrease of the local geometrical order of the first shell as polyvalent cations are inserted. © 1999 American Chemical Society
Study of amorphous and crystalline lithium vanadium oxide (Li1+xV3O8) by FTIR, XAS and electrochemical techniques.
No full textNickel hexacyanoferrate membrane as a coated wire cation-selective electrode
No full textNickel hexacyanoferrates containing alkali metal cations as counter ions were used to prepare ion-selective electrodes for potentiometric sensing of intercalated species in the coated wire electrode (CWE) configuration. All the electrodes developed display a quasi-Nernstian response towards potassium ion, whereas the highest sensitivity is generally achieved when Cs+ is the counter cation in the sensing material. The selectivity constants of the electrodes were calculated by the matched potential method considering K+ as the primary ion. The selectivity order is Cs+ > K+ > Na+ > Li+ and reflects the effective dimension of the hydrated cations
- …
