Search results for "Prussian Blue"
showing 10 items of 57 documents
Chronoamperometry of prussian blue films on ITO electrodes: Ohmic drop and film thickness effect
1999
Abstract The chronoamperograms associated with the reduction of prussian blue films deposited onto indium tin oxide (ITO) electrodes to the Everitt’s salt form, are influenced by the ohmic drop effect. These chronoamperometric curves have been simulated by means of a numerical finite difference model which is able to explain their shape and their dependence on the thickness of the film and on the uncompensated resistance. An analytical expression which describes the dependence of current against time at initial times considering the ohmic drop effect has also been proved when applied to these chronoamperometric curves at short times.
A numerical approach to the voltammograms of the reduction of Prussian Blue films on ITO electrodes
1997
The uncompensated resistance, mainly due to the ITO electrode, modifies the shape of voltammetric curves of the system Prussian Blue ⇄ Everitt's Salt films deposited on this transparent electrode. A numerical finite difference model which is able to explain the shape of these voltammetric curves is studied in this paper. This model explains the dependence of voltammetric curves on the film thickness and uncompensated resistance.
Photomagnetism of Molecular Systems
2001
This article reviews various classes of transition metal compounds which display in the solid state light sensitive electronic structure modifications accompanied by drastic changes of their magnetic and/or optical properties, i.e., photomagnetism. Selected examples from this rapidly expanding field, include spin crossover, stilbenoid and nitrosyl complexes, as well as Prussian blue analogues.
Correction of mass drift in ac-electrogravimetry of Prussian Yellow films. Mass impedance under apparently non-steady state condition
2014
Abstract Mass impedance spectroscopy allows the modulated response of mass of a resonant electrode to be followed at different perturbation frequencies during electrochemical impedance spectroscopy experiments (ac-electrogravimetry). However, some difficulties appear if a continuous mass change takes place foreign to the mass changes due to the ac-modulated electrochemical processes. A new strategy is proposed to solve this limitation. Both, mass and potential analog signals are recorded frequency by frequency from 100 Hz up to the lowest frequencies. Then, a numerical procedure based on a multiparametric fitting of raw data against the elapsed time allows the contribution due to the modula…
Interfacial role of Cesium in Prussian Blue Films
2015
The simultaneous measurement of current, mass, motional resistance and absorbance magnitudes allows the electrochemical cation insertion process to be explained during successive voltammograms around the Prussian Blue ⇄ Everitt's Salt system in CsCl aqueous acid solutions. Two different ways for the entrance of cesium to the porous structure of Prussian Blue have been observed. Firstly, Cs+ is spontaneously absorbed as CsCl into the interstitial cluster of water of the channels formed by the Fe(II)low spinCNFe(III)high spin structural units of the crystal. This chemical absorption involves a spontaneous substitution of inner water molecules of the interstitial water cluster. Finally, Cs+ …
Estimation of individual Gibbs energies of cation transfer employing the insertion electrochemistry of solid Prussian blue
2011
Abstract A novel method to determine the Gibbs energy of cation transfer between two miscible solvents is described. This method uses electrochemical data for the reversible cation-assisted solid-state reduction of Prussian blue using ferrocene as internal potential standard. Voltammetric data can be used for a direct measurement of the Gibbs energy of ion transfer from one solvent to another using midpeak potentials in solutions of suitable salts in each one of the solvents separately or mixtures of the solvents. Excess Gibbs energies of solvation in solvent mixtures can also be directly estimated. Gibbs energies of cation transfer of Li+, Na+ and K+ ions from water to MeOH, MeCN and DMSO …
Photoinduced effects on the magnetic properties of the (Fe0.2Cr0.8)1.5[Cr(CN)6] Prussian blue analogue
2019
International audience; One of the most attractive characteristics of some Prussian blue derivatives is the sensitivity of their magnetic properties to the irradiation with light. In this work photoinduced effects in the (Fe0.2Cr0.8)1.5[Cr(CN)6]·15H2O PBA have been studied by means of X-ray-based spectroscopies and magnetometry. It is found that the photosensitivity of this compound is mostly centred on the Fe cations: the exposure to green light induces a transfer of electrons from them to the Cr that provokes a reversal of the previously existing linkage isomerization and increases the elastic strain caused by the misfit of the unit cells of the Fe–NC–Cr and Cr–NC–Cr sublattices. The gree…
Enhancing the electrocatalytic activity and stability of Prussian blue analogues by increasing their electroactive sites through the introduction of …
2021
Prussian blue analogues (PBAs) have been proven as excellent Earth-abundant electrocatalysts for the oxygen evolution reaction (OER) in acidic, neutral and alkaline media. Further improvements can be achieved by increasing their electrical conductivity, but scarce attention has been paid to quantify the electroactive sites of the electrocatalyst when this enhancement occurs. In this work, we have studied how the chemical design influences the specific density of electroactive sites in different Au-PBA nanostructures. Thus, we have first obtained and fully characterized a variety of monodisperse core@shell hybrid nanoparticles of Au@PBA (PBA of NiIIFeII and CoIIFeII) with different shell siz…
Charge-transfer driven by ultrafast spin-transition in a CoFe Prussian blue analogue
2020
Photoinduced charge-transfer is an important process in nature and technology and is responsible for the emergence of exotic functionalities, such as magnetic order for cyanide-bridged bimetallic coordination networks. Despite its broad interest and intensive developments in chemistry and material sciences, the atomic-scale description of the initial photoinduced process, which couples intermetallic charge-transfer and spin transition, has been debated for decades; it has been beyond reach due to its extreme speed. Here we study this process in a prototype cyanide-bridged CoFe system by femtosecond X-ray and optical absorption spectroscopies, enabling the disentanglement of ultrafast electr…
The role of potassium and hydrogen ions in the Prussian Blue ⇆ Everitt's Salt process
1998
Cyclic voltammetry experiments have proved very useful in the knowledge and understanding of the role of the potassium and hydrogen ions during the Prussian Blue ⇄ Everitt's Salt process. While potassium ions act as a stoichiometric reactant, the hydrogen ions play a very important role in the kinetics of the electron-hopping process. The entropy change for the reaction PB ⇄ ES has proved to be dependent on the degree of crystallinity of the film, indicating that this entropy change is related to the fixation of inner counterions on the crystal structure of the films.