Search results for "PRUSSIAN BLUE"
showing 10 items of 57 documents
Mixed Valence Materials: Prussian Blue Analogues of Reduced Dimensionality (Small 16/2012)
2012
Electrochemistry of TiO2–iron hexacyanocobaltate composite electrodes
2014
Abstract In this paper we investigate the electrochemical behavior of iron hexacyanocobaltate (FeHCC) in comparison to the cobalt hexacyanoferrate (CoHCF). The best results were achieved on electrochemical synthesized film of FeHCC on the TiO2 modified electrodes. The chemical and physical characterizations confirm the formation of the FeHCC with the classical cubic crystal structure of the Prussian blue analogs, with cell parameter a very close to 10 A, as well as the formation of micro aggregates of TiO2 covered by FeHCC. The synthesis was performed on various substrates such as glassy carbon (GC), graphite foil (GF) and indium tin oxide (ITO) in order to develop new technological applica…
On/Off Photoswitching in a Cyanide-Bridged {Fe2Co2} Magnetic Molecular Square
2013
International audience; A repeatable bidirectional paramagnetic ↔ diamagnetic photomagnetic effect has been observed in the cyanide-bridged Fe-Co square complex {[Fe{B(pz)(4)}(CN)(3)](2)[Co(bik)(2)](2)}(ClO(4))(2)*3H(2)O [B(pz)(4) = tetrapyrazolylborate, bik = bis(1-methylimidazol-2-yl)ketone]. Magnetic measurements and low-temperature single-crystal X-ray diffraction experiments have shown that a complete electron transfer from the diamagnetic Fe(II)-Co(III) state to the paramagnetic Fe(III)-Co(II) metastable state is induced by 808 nm laser light irradiation, whereas the diamagnetic state is recovered in an almost quantitative yield under irradiation at 532 nm.
Insights on the Mechanism of Insoluble-to-Soluble Prussian Blue Transformation
2009
The electrochemical transformation of the soluble form of Prussian blue (PB) material from the insoluble form was monitored using electrochemical, gravimetric, acoustic, and spectroscopic techniques simultaneously. The described combination of in situ techniques represents an innovative tool for measurement in electrochemistry, which provides complementary information on the electrochemical systems. The insoluble-to-soluble PB transformation process takes place during the successive voltammetric cycles between the mixed valence form (PB) and the fully reduced form [Everitt's salt (ES)]. One of the processes that takes place is the exit of free Fe(CN) 4- 6 ions occluded in the vacancies of t…
Ionic and Free Solvent Motion in Poly(azure A) Studied by ac-Electrogravimetry
2011
International audience; This work is focused on the mechanistic aspects of the redox behavior of poly(azure A) taking advantage of the controlled modulation of their oxidation states by ac-electrogravimetry. The originality of this technique is its ability to discriminate between cation and anion involved in the charge compensation process and the accompanying free solvent transfer, directly or indirectly. Two processes were proposed where the faster ionic exchange is considered to be the participation of the anion species acting as counterions whereas the slower one is related to the proton transfer. The proton is implied as reactants for the two electroactive sites identified in the polym…
Prussian Blue Analogues of Reduced Dimensionality
2012
Abstract: Mixed-valence polycyanides (Prussian Blue analogues) possess a rich palette of properties spanning from room-temperature ferromagnetism to zero thermal expansion, which can be tuned by chemical modifications or the application of external stimuli (temperature, pressure, light irradiation). While molecule-based materials can combine physical and chemical properties associated with molecular-scale building blocks, their successful integration into real devices depends primarily on higher-order properties such as crystal size, shape, morphology, and organization. Herein a study of a new reduced-dimensionality system based on Prussian Blue analogues (PBAs) is presented. The system is …
Magnetic ordering in an (Fe0.2Cr0.8)1.5[Cr(CN)6] Prussian blue analogue studied with synchrotron radiation based spectroscopies
2018
The appearance of magnetic order in the (Fe0.2Cr0.8)1.5[Cr(CN)6]·15H2O Prussian blue analogue at low temperature has been investigated by means of synchrotron radiation-based X-ray absorption spectroscopy and X-ray magnetic circular dichroism. With the help of ligand field multiplet analysis we have been able to identify the oxidation states of the metallic cations present in the sample and their evolution with temperature. Our experiments reveal that the appearance of ferromagnetic order is triggered by the transformation of CrIII cations to CrII high-spin caused by a transfer of electrons from the Fe to the Cr resulting in an increase of the magnetic interactions within the (Cr, Cr) subla…
Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule
2014
[EN] A hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl-LDH ferromagnetic layers intercalated with thermoresponsive 4-(4-anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In…
Photo-switching in a hybrid material made of magnetic layered double hydroxides intercalated with azobenzene molecules.
2014
Financial support from the EU (Projects HINTS FP7-263104-2 and SpinMol Advanced Grant ERC-2009-AdG-20090325), the Spanish Ministerio de Economia y Competitividad (Projects with FEDER cofinancing MAT 2009-14528-C02-01, MAT2011-22785, MAT2012-38567-C02-01, CTQ-2011-26507, Consolider-Ingenio in Molecular Nanoscience CSD2007-00010, Consolider-Ingenio 2010-Multicat CSD2009-00050, and Severo Ochoa Program SEV-2012-0267), Generalitat Valenciana (PROMETEO and ISIC-Nano programs), and VLC/Campus Microcluster "Functional Nanomaterials and Nanodevices" is gratefully acknowledged. C. M. G. thanks the Spanish MINECO for a Ramon y Cajal Fellowship (RYC-2012-10894). We also acknowledge P. Atienzar and J. …
Prussian blue@MoS2 layer composites as highly efficient cathodes for sodium- and potassium-ion batteries
2018
Prussian blue (PB) represents a simple, economical, and eco‐friendly system as cathode material for sodium‐ion batteries (SIBs). However, structural problems usually worsen its experimental performance thus motivating the search for alternative synthetic strategies and the formation of composites that compensate these deficiencies. Herein, a straightforward approach for the preparation of PB/MoS2‐based nanocomposites is presented. MoS2 provides a 2D active support for the homogeneous nucleation of porous PB nanocrystals, which feature superior surface areas than those obtained by other methodologies, giving rise to a compact PB shell covering the full flake. The nanocomposite exhibits an ex…