Co-Fe普鲁士蓝类配合物纳米颗粒的微乳液法制备与表征

Highly oriented cubic, hollow cubic and spherical nanoparticles of cobalt-iron Prussian blue analogues were synthesized in poly oxyethylene tertoctylphenyl ether (TritonX-100)/n-hexanol/cyclohexane microemulsion. The effects of the water-to-surfactant molar ratio (w), the reactant concentration and the reaction temperature on the morphology of cobalt-iron Prussian blue analogues were studied. The samples were characterized by transmission electron microscopy (TEM), field emission scan electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and infrared spectroscopy (IR).     

Metal-to-ligand and ligand-to-metal charge transfer in thin films of Prussian blue analogues investigated by X-ray absorption spectroscopy

A series of thin films of Prussian blue analogues is investigated by X-ray absorption spectroscopy (XAS) at the Fe, Co and Mn L(2,3)-edges. The ligand field multiplet theory enables us to examine accurately the electronic structure of these materials. Experimental XAS spectra of CoFe Prussian blue analogues are successfully reproduced using a ground state configuration including metal-to-ligand (MLCT) and ligand-to-metal charge transfer (LMCT) at the Co and Fe L(2,3)-edges. In particular, a huge improvement is achieved for satellite peaks at the Co(iii) L(2,3)-edges compared to previous calculations in the literature based on LMCT effects only. On the other hand, XAS spectra of MnFe analogues synthesized for the first time, can be reproduced conveniently by taking into account either MLCT or LMCT depending on the conditions of the sample preparation. For each thin film, the proportion of the different oxidation states of Co, Fe and Mn is evaluated. Unexpectedly, this analysis reveals the presence of a significant amount of a reduced phase, which turns out to be strongly dependent on the sample synthesis and storage conditions.     

NaKCoFe普鲁士蓝类配合物纳米颗粒的磁性研究

在2-乙基己基琥珀酸酯磺酸钠(AOT)/异辛烷/水微乳液体系内,通过改变w值(水与AOT的物质的量之比)和反应物浓度比例得到了5nm球形至80nm立方状的NaKCoFe普鲁士蓝类配合物。发现w值和反应物浓度比不仅影响产物的形貌,而且影响配合物的结构。用UV、XRD、EDS、ICP、IR和超导量子干涉仪(SQUID)等对产品进行了结构和磁学性能的表征,发现影响产物磁性的主要因素是碱金属的含量。     

Charge‐Transfer Phase Transition of a Cyanide‐Bridged FeII/FeIII Coordination Polymer

Heterometallic Prussian blue analogues are known to exhibit thermally induced charge transfer, resulting in switching of optical and magnetic properties. However, charge‐transfer phase transitions have not been reported for the simplest FeFe cyanide‐bridged systems. A mixed‐valence Fe^II/Fe^III cyanide‐bridged coordination polymer, {[Fe(Tp)(CN)₃]₂Fe(bpe)?5 H₂O}_n, which demonstrates a thermally induced charge‐transfer phase transition, is described. As a result of the charge transfer during this phase transition, the high‐spin state of the whole system does not change to a low‐spin state. This result is in contrast to FeCo cyanide‐bridged systems that exhibit charge‐transfer‐induced spin transitions.     

Prussian blue: a new framework of electrode materials for sodium batteries

Prussian blue and its analogues consisting of different transition-metal ions (Fe, Mn, Ni, Cu, Co and Zn) have been synthesized at room temperature. Insertion of Na into KFe(2)(CN)(6) in a carbonate electrolyte exhibited a reversible capacity near 100 mA h g(-1) with no capacity fade in 30 cycles. The data indicate that a Na-ion battery with a Prussian blue framework as a cathode will be feasible.     

Mesoporous Prussian Blue Analogues: Template‐Free Synthesis and Sodium‐Ion Battery Applications

The synthesis of mesoporous Prussian blue analogues through a template‐free methodology and the application of these mesoporous materials as high‐performance cathode materials in sodium‐ion batteries is presented. Crystalline mesostructures were produced through a synergistically coupled nanocrystal formation and aggregation mechanism. As cathodes for sodium‐ion batteries, the Prussian blue analogues all show a reversible capacity of 65 mA h g^?1 at low current rate and show excellent cycle stability. The reported method stands as an environmentally friendly and low‐cost alternative to hard or soft templating for the fabrication of mesoporous materials.     

Nonlinear magnetooptical effects caused by piezoelectric ferromagnetism in F3m-type Prussian blue analogues

The second harmonic generation (SHG) and magnetization-induced SHG (MSHG) of AMA[MB(CN)6]-type (F3m) Prussian blue analogues (i.e., CsCo[Cr(CN)6].0.5H2O and RbMn[Fe(CN)6]) were observed. A large interaction between the nonlinear optical response and magnetic spins was observed in CsCo[Cr(CN)6].0.5H2O. These observations of SHG and MSHG imply that AMA[MB(CN)6]-type Prussian blue analogues are piezoelectric above the Curie temperature (TC) and piezoelectric ferromagnet below TC.     

Photoinduced magnetism in core/shell Prussian blue analogue heterostructures of K(j)Ni(k)[Cr(CN)6]l·nH2O with Rb(a)Co(b)[Fe(CN)6]c·mH2O

Core/shell and core/shell/shell particles comprised of the Prussian blue analogues K(j)Ni(k)[Cr(CN)(6)](l)·nH(2)O (A) and Rb(a)Co(b)[Fe(CN)(6)](c)·mH(2)O (B) have been prepared for the purpose of studying persistent photoinduced magnetization in the heterostructures. Synthetic procedures have been refined to allow controlled growth of relatively thick (50-100 nm) consecutive layers of the Prussian blue analogues while minimizing the mixing of materials at the interfaces. Through changes in the order in which the two components are added, particles with AB, ABA, BA, and BAB sequences have been prepared. The two Prussian blue analogues were chosen because B is photoswitchable, and A is ferromagnetic with a relatively high magnetic ordering temperature, ~70 K, although it is not known to exhibit photoinduced changes in its magnetic properties. Magnetization measurements on the heterostructured particles performed prior to irradiation show behavior characteristic of the individual components. On the other hand, after irradiation with visible light, the heterostructures undergo persistent photoinduced changes in magnetization associated with both the B and A analogues. The results suggest that structural changes in the photoactive B component distort the normally photoinactive A component, leading to a change in its magnetization.     

Photo-induced charge transfer in Prussian blue analogues as detected by photoacoustic spectroscopy

The photo-induced charge transfer in four series of Prussian blue (PB) analogues was studied from photoacoustic spectra. In cobalticyanides the observed signals were assigned to a metal-to-ligand charge transfer, which appears as a shoulder below 450 nm, and to d-d transitions for Co(II), Ni(II) and Cu(II) complex salts. No evidence of metal-to-metal charge transfer was observed for this series, which is probably due to the high stability of low spin cobalt(III) in the hexacyanide complex. Photoacoustic spectra for ferricyanides are broad bands, which result particularly intense up to 750 nm. Such features were attributed to the overlapping of contributions from metal-to-ligand (<600 nm) and metal-to-metal charge transfer transitions, with probably also a minor contribution from d-d transitions in the outer metal. The spectra for the ferrocyanides series are dominated by the metal-to-ligand charge transfer band below 550 nm, approximately 100 nm above this transition in cobalticyanides. Within the studied solids, the most intense and broad metal-to-metal charge transfer bands were found for a series of low spin Co(III) high spin Co(II) hexacyanoferrates(II,III) and with similar features also for ferric ferrocyanide (Prussian blue), assigned to Fe(II)-->Co(III) and Fe(II)-->Fe(III) photo-induced transition, respectively. The first of these transitions requires of more energetic photons to be observed, its maximum falls at 580 nm while for Prussian blue it is found at 670 nm. Prussian blue analogues are usually obtained as nanometric size particles and many of them have a microporous structure. The role of surface atoms on the observed charge transfer bands in the studied series of compounds is also discussed.     

New observations on the solubility of prussian blue

1. Alkali metaphosphates and alkali polyphosphates dissolve Prussian blue to potassium ferrocyanide and to the corresponding ferric alkali metaphosphates and polyphosphates. But smaller quantities peptize Prussian blue. The alkali metaphosphates and alkali polyphosphates are the first inorganic substances whose peptizing action on Prussian blue was observed. 2. The alkali salicylates and alkali β-resorcylates react in an analogous way with Prussian blue. They dissolve Prussian blue if sufficient quantities are present. But smaller quantities yield colloidal Prussian blue. 3. The statement in the literature that Turnbull's blue is not peptized by potassium oxalate is erroneous. Simultaneously, the conclusion had to be drawn that Turnbull's blue is an equimolecular mixture of Prussian blue and ferrous ferrocyanide. 4. Data given in the literature describing some reactions leading to colloidal Prussian blue and stating that Prussian blue does not react with hydrobromic acid are erroneous.     

Zero thermal expansion in a Prussian Blue analogue

Isotropic nearly zero thermal expansion (i.e., negligible volume change) is reported in a large temperature range for Fe[Co(CN)6], a member of the Prussian blue family with electronically active metal sublattices and a cubic framework structure built by a cyanide-bridged network of octahedral units. Suitable selection of metal ions and interstitial units could allow such anomalous thermal behavior to be combined with the variety of unusual electronic, optical, and magnetic properties exhibited by Prussian blue analogues.     

Is It Possible To Get High TC Magnets with Prussian Blue Analogues? A Theoretical Prospect

Theoretical methods based on density functional theory have been employed to search for Prussian blue analogues with Curie temperatures higher than the ones reached today. Our study suggests several possible cyano-bridged compounds as candidates to present stronger exchange coupling and higher ordering temperatures than the well known Cr(III)V(II) derivatives.     

Polyanionic Compounds for Potassium‐Ion Batteries

Lithium‐ion batteries have the highest energy density among practical secondary batteries and are widely used for electronic devices, electric vehicles, and even stationary energy‐storage systems. Along with the expansion of demand and applications, the concern about resources of lithium and cobalt is growing. Therefore, secondary batteries composed of abundant elements are required to complement lithium‐ion batteries. In recent years, the development of potassium‐ion batteries has attracted much attention, especially for large‐scale energy storage. In order to realize potassium‐ion batteries, various compounds are proposed and investigated as positive electrode materials, including layered transition‐metal oxides, Prussian blue analogues, and polyanionic compounds. This article offers a review of polyanionic compounds which are typically composed of abundant elements and expected high operating potential. Furthermore, we deliver our new results to partially compensate for lack of studies and provide a future perspective.     

Observation of the anisotropic photoinduced magnetization effect in Co-Fe Prussian blue thin films fabricated by using clay Langmuir-Blodgett films as a template

Thin films of cobalt-iron cyanide (Co-Fe Prussian blue) have been fabricated by means of the modified Langmuir-Blodgett (LB) method using a smectite clay mineral (montmorillonite). In this combined method, clay LB films play a template role in the formation of the Co-Fe Prussian blue thin layer. The films were revealed to possess a well-organized structure not only in perpendicular directions to the film surface but also in parallel directions to the film surface. The photoinduced electron transfer from the iron ion to the cobalt through the bridging cyanide in the films occurred at low temperature (8 K), similar to that in the bulk Co-Fe Prussian blue. The films clearly exhibited magnetic anisotropy with regards to the direction of the applied magnetic field. Moreover, the photoinduced magnetization effect in the films was also found to be anisotropic.     

Molecule-based room-temperature magnets: catalytic role of V(III) in the synthesis of vanadium-chromium Prussian blue analogues

A new synthetic procedure to obtain vanadium-chromium Prussian blue analogues is presented, using controlled amounts of V(III) in solution during the synthesis. The vanadium and chromium oxidation states and the chemical environment of the metal ions in the solids are characterized by infrared and X-ray absorption spectroscopies. The presence of weak amounts of V(III) during the synthesis provides materials which are better organized and present reproducible Curie temperature and magnetization at saturation in agreement with the observed V/Cr stoichiometry.     

Electrochromism and electrochemical magnetism in Ni–Fe Prussian blue

We studied the electrochemical and magnetic properties of NiFe Prussian blue. The NiFe Prussian blue was synthesized on Ni electrodes in the form of thin films by an electrochemical technique. Measurements of its magnetic properties show that NiFe Prussian blue with the Fe^{III-low spin (LS)}–CN–Ni^II structure exhibits ferromagnetic properties, with T _c (critical temperature)=25 K. On the other hand, the reduced form, which has the Fe^II-LS–CN–Ni^II structure, is paramagnetic. This means that the magnetic properties can be controlled between ferromagnetic and paramagnetic by an electrochemical method. Furthermore, it is well known that NiFe Prussian blue exhibits electrochromic properties. Hence, this compound is a multifunctional, molecule-based compound in which optical and magnetic properties can be controlled by an electrochemical redox reaction. Contribution to the special issue on “Magnetic field effects in Electrochemistry.”     

Prussian blue solid-state films and membranes as potassium ion-selective electrodes

The use of thin films of Prussian blue and heterogeneous Prussian blue membranes as potassium ion-selective electrodes was investigated. All of the heavier group I cations and NH⁺₄ interfere strongly but there is relatively good selectivity towards Na⁺ with a selectivity coefficient of ca. 5 × 10^?3. The thin-film measurements, based on Prussian blue deposited on platinum, involve conditioning the electrode to a fixed potential according to the method used by Engel and Grabner for copper hexacyanoferrate(III) films. The membrane electrodes were based on mixing Prussian blue with polymeric supporting films such as polystyrene and epoxy. A particularly simple practical configuration involves Prussian blue membranes deposited directly on copper conductors where one membrane serves as a reference electrode. A reversible cell, without liquid junction, is formed with Prussian blue and Ag/AgCl electrodes and this serves as a means for determining an accurate value for the standard reduction potential of Prussian blue, which is found to be 0.238 V vs. Ag/AgCl at 25 °C.     

普鲁士兰修饰电极的现场X射线衍射研究

利用Ｘ射线衍射仪－电化学装置－两台微机联机组成的Ｘ射线衍射差谱全自动电化学测量系统，并结合特制的电解池，现场测定了普鲁士兰修饰电极薄膜在电化学变过程中的Ｘ射线衍射差谱。结果证实在变色过程为了平衡体系电荷而进入和脱出修饰薄摸的Ｋ＾＋导致了薄膜晶体结构的转变。理论计算的Ｘ射线衍射差谱与实测结果基本一致。     

Photoinduced magnetization in molecular compounds

In this review, recent studies on photoinduced magnetization in molecular compounds are introduced. The magnetic materials presented here range from Prussian blue analogues to purely organic radicals. Various photomagnetic phenomena observed in those materials are briefly described. These are, for example, photoinduced magnetization, photoinduced demagnetization, photoinduced spin cluster, photoinduced magnetic-pole inversion, photoinduced spin flipping, light-induced excited spin state trapping, photoinduced valence tautomerism, etc. It is thought that these can be used for future high-density photo-recording media and optical switches in molecular devices.     

Progress of Prussian Blue and Its Analogues as Cathode Materials for Potassium Ion Batteries

Environmental pollution and the energy crisis have promoted the development of clean energy as well as new-generation energy storage systems. Potassium ion batteries (PIBs) have emerged as a possible alternative to lithium-ion batteries due to their abundant reserves, low cost, and impressive electrochemical performance. However, the search for suitable cathode materials has become particularly crucial. Recently, Prussian blue (PB) has been investigated as a potential cathode material for PIBs, which has an open three-dimensional framework to accommodate a large volume of potassium ions and adjustable composition for different applications. In this review, Prussian blue and its analogues (PBAs) and their application in PIBs were summarized detailly. We presented the composition, structure, potassium ion storage mechanism, preparation process of PBAs, and then focus on the performance optimization methods of the PBAs, including transition metal doping and conductive material adding into PBAs. Finally, the challenges as well as the outlook on the future development of PBAs were proposed for further application in this battery system.