Indium Hexacyanoferrate Research Articles

Open-framework indium hexacyanoferrate for high-voltage and coaxially-fibrous aqueous K//Zn battery

The design of eco-friendly fibrous aqueous rechargeable Zn-based batteries is important for the advancement of flexible electronics. But it is still remains extremely difficult to develop high-voltage fibrous Zn-based batteries on a single-fiber architecture that directly influence their energy density. Furthermore, the sluggish Zn2+ diffusion kinetics and tough electrostatic interaction seriously astrict to further move ahead for the Zn-based batteries. Herein, we demonstrate a high-voltage coaxially-fibrous aqueous rechargeable (CFAR) K//Zn battery based on open-framework indium hexacyanoferrate (InHCF) cathode. The resultant assembled CFAR K//Zn battery provides an eminent voltage of 1.70 V and a superhigh energy density of 197.88 mWh cm-3 at 170.4 mW cm-3. More importantly, our assembled CFAR K//Zn battery exhibits excellent mechanical steadiness with the capacity retention of 92.7 % by following bending at 90° for 4000 times. Therefore, the design of the new-style architecture in high-voltage CFAR K//Zn batteries provides a fresh strategy for economic, reliable, and high-energy-density wearable energy-storage devices.

Surface Modification with Metal Hexacyanoferrates for Expanding the Choice of H2‐Evolving Photocatalysts for Both Fe3+/Fe2+ Redox‐Mediated and Interparticle Z‐Scheme Water‐Splitting Systems

The construction of Z‐scheme water splitting systems is an effective approach toward harvesting a wide portion of the solar light spectrum; however, the success has often depended on the property of photocatalyst surfaces. This drawback is typified by the limited choice of efficient H2 evolution photocatalysts (HEPs) (e.g., Rh‐doped SrTiO3) for Z‐scheme water splitting using Fe3+/Fe2+ redox couple. The majority of visible light‐responsive materials shows low activity for H2 production with Fe2+ electron donors despite having suitable band levels, probably due to the absence of an effective surface site for oxidizing Fe2+. The choice of HEPs for interparticle Z‐scheme systems has also been limited. Herein, an effective strategy for overcoming these limitations is reported: activation of originally inactive materials via surface modification with metal hexacyanoferrate nanoparticles. Photocatalytic H2 evolution over TaON in aqueous Fe2+ solution is drastically enhanced by comodification with indium hexacyanoferrate (InHCF) and Rh–Cr mixed oxide. InHCF promotes Fe2+ oxidation to Fe3+ utilizing the holes photogenerated in TaON via FeIII/FeII redox cycles, enabling Z‐scheme water splitting with the Fe3+/Fe2+ redox mediator coupled with an O2 evolution photocatalyst under visible light. It is also disclosed that InHCF nanoparticles function as effective solid electron mediators for achieving interparticle Z‐scheme water splitting.

High voltage and superior cyclability of indium hexacyanoferrate cathodes for aqueous Na-ion batteries enabled by superconcentrated NaClO4 electrolytes

Highly-concentrated aqueous NaClO4 electrolyte enables the high working voltage and superior cyclability of NaIn[Fe(CN)6]. Furthermore, a guideline for tuning the working potential of Prussian Blue Analogs is demonstrated.

An aqueous aluminum-ion electrochromic full battery with water-in-salt electrolyte for high-energy density

Electrochromic batteries (EBs) have been developed as a technical breakthrough to solve the energy issues of storage and saving. Multivalent-ions (Zn2+, Mg2+ and Al3+) have recently demonstrated attractive properties for EBs due to their multiple-electron redox nature. However, still now, reported multivalent-ion EBs are typically assembled with a small-area metallic anode and a large-area electrochromic cathode. Non-uniformity of coloration and unstable metal plating/stripping hinder the developments of these devices. Additionally, insufficient energy/power density of EBs is a huge technical challenge needed to be overcome. In this work, we demonstrated a new aqueous aluminum-ion electrochromic full battery (AIEFB) to overcome the challenges. Systematic studies of density functional theory calculation, molecular dynamics simulation, electrochemical analysis, and mechanical measurements were conducted to optimize electrode materials and electrolyte. A water-in-salt (WIS) Al(OTF)3 electrolyte and a new electrochromic material couple of anodic amorphous WO3 (a-WO3) and cathodic indium hexacyanoferrate (InHCF) were exploited for AIEFB. The AIEFB demonstrated advantages of a high average discharge potential (1.06 V), an attractive energy density of 62.8 mWh m−2 at a power density of 2433.8 mW m−2, a high transmittance modulation of 63% at 600 nm, and a distinct transparent-to-deep blue coloration during the Al-ion shuttling processes.

Effects of Intra-Structural Interactions of Indium Hexacyanoferrate on the Li+ and K+ Intercalation Potential

Due to the lithium reserves for the growing sector of lithium-ion batteries (LIBs), there has been an increased interest in the development of new technologies based on the reactions with other ions, as Sodium (NIBs) and Potassium (KIBs) ion Batteries. Particularly, the intercalation potentials of NIBs are lower than LIBs, limiting their application, for this reason the KIBs are a promising option. Since lithium has a higher polarizing power than potassium, it is expected that the cation-structure interactions influence the intercalation potential. So, in this work we carefully evaluated the structural changes induced by the interactions of Li or K ions with an open framework structure (indium hexacyanoferrate) without water. The lack of water within the structure is important since new intra-interaction phenomena arise, which have not been previously analyzed, providing deeper insights of the importance of the various interactions in this kind of system. The intercalation potentials were evaluated by CV and galvanostatic experiments in a non-aqueous system using a mix of solvent, demonstrating a higher potassium intercalation voltage of 3.9 V vs K+/K in comparison to Lithium 3.3 V vs Li+/Li. The nature of such high potential is evaluated around the electronic structure alterations arising from internal structural modifications and intra structural interactions leading to changes in the way that the ion is interacting with the framework. The lowest formal potential shown in presence of lithium as intercalation ion, can be attributed to a noticeable anisotropy in the charge density on the Fe–(CN)6 octahedron provoking distortions of the molecular block FeCN6, as was confirmed by infrared analysis and Density Functional Theory calculations.

A Ca‐Ion Electrochromic Battery via a Water‐in‐Salt Electrolyte

AbstractMultivalent‐ion batteries with electrochromic functionality are an emerging green technology for development of low‐carbon society. Compared to Mg2+, Zn2+ and Al3+, Ca2+ has a low polarization strength similar to that of Li+, therefore Ca2+ for electrochromism and battery can avoid kinetic issues caused by other multivalent‐ions with high polarization strength. Here, by exploiting Ca‐ion carriers for electrochromism and a water‐in‐salt (WIS) Ca(OTF)2 electrolyte for the first time, a new and safe aqueous Ca‐ion electrochromic battery (CIEB) has been demonstrated. The WIS Ca(OTF)2 electrolyte demonstrates enhanced anion‐cation interactions and decreased water activity. Vanadium oxide (VOx) and indium hexacyanoferrate (InHCF) films are respectively developed as anode and cathode because of their stable and high‐rate Ca2+ insertion/extraction, as well as matched electrochromism. The CIEB demonstrates a stable and high‐rate capability, a high energy density of 51.4 mWh m−2 at a power density of 1737.3 mW m−2, and a greenish yellow‐to‐black electrochromism. The presented results are beneficial for understanding redox kinetics in WIS electrolytes, and inspire researches on batteries and electrochromism with multivalent‐ions.

A rechargeable aqueous proton battery based on a dipyridophenazine anode and an indium hexacyanoferrate cathode.

A rocking-chair aqueous proton battery is assembled by using dipyridophenazine and indium hexacyanoferrate as the anode and cathode materials, respectively. The reversible amination of redox-active phenazine moieties in dipyridophenazine and fast intercalation-deintercalation of protons in hexacyanoferrate enable the aqueous proton battery to achieve a reversible specific capacity of 37 mA h g-1 at 1 A g-1, good cycling stability with 76.1% capacity retention over 3000 cycles and excellent rate capability.

Highly Sensitive and Exceptionally Wide Dynamic Range Detection of Ammonia Gas by Indium Hexacyanoferrate Nanoparticles Using FTIR Spectroscopy.

Ammonia gas is useful but caustic; thus, its concentration is monitored depending on applications. We prepared indium hexacyanoferrate nanoparticles (InHCF-NPs, HCF = [FeII(CN)6]4-) with average diameter around 8 nm by simple reaction at room temperature between In cations and HCF anions, and we found the unique functionality of InHCF-NPs which were capable of highly sensitive (16 ppb) and exceptionally wide range (190000, 16 ppb -0.3%) detection of ammonia gas within 6 min by IR measurements. Slope changes of the IR peak ratio of adsorbed ammonium over CN moieties in the InHCF framework indicated a good log-log linear correlation along gas concentrations, in which a wide dynamic range over 105 was realized for the first time in the field of ammonia gas detection.

Water-mediated cation intercalation of open-framework indium hexacyanoferrate with high voltage and fast kinetics.

Rechargeable aqueous metal-ion batteries made from non-flammable and low-cost materials offer promising opportunities in large-scale utility grid applications, yet low voltage and energy output, as well as limited cycle life remain critical drawbacks in their electrochemical operation. Here we develop a series of high-voltage aqueous metal-ion batteries based on ‘M+/N+-dual shuttles' to overcome these drawbacks. They utilize open-framework indium hexacyanoferrates as cathode materials, and TiP2O7 and NaTi2(PO4)3 as anode materials, respectively. All of them possess strong rate capability as ultra-capacitors. Through multiple characterization techniques combined with ab initio calculations, water-mediated cation intercalation of indium hexacyanoferrate is unveiled. Water is supposed to be co-inserted with Li+ or Na+, which evidently raises the intercalation voltage and reduces diffusion kinetics. As for K+, water is not involved in the intercalation because of the channel space limitation.

Stability-enhanced indium hexacyanoferrate electrodes: Morphological characterization, in situ EQCM analysis in nonaqueous electrolytes and application to a WO 3 electrochromic device

This paper presents a promising transparent counterelectrode system for a WO 3 electrochromic device (ECD) on the basis of a stability-enhanced indium hexacyanoferrate (InHCF) electrode and a NaClO 4/propylene carbonate (PC) electrolyte. Through SEM characterization it was found that clusters of granular InHCF nanoparticles (ca. 80–140 nm) were deposited on ITO substrates in HCl and KCl-stabilized plating solutions, and uniform micrometer thick films with high charge capacity could be obtained. From in situ electrochemical quartz crystal microbalance study, it was discovered that Na + would enter or move out from the InHCF film in the “desolvated” form during the redox process in a PC electrolyte. Besides, NaClO 4/PC resulted in higher electrochemical activity and reversibility than LiClO 4/PC. With these discoveries, a durable WO 3-InHCF ECD featuring blue-to-colorless electrochromism was fabricated successfully. The device remained 73.6 and 88.7% of its initial Δ T values at 600 and 800 nm after 40,000 rapid and successive coloring/bleaching cycles, respectively. Moreover, the cycling-induced loss of electrochromic performance almost completely restored after 1-month rest and kept unchanged for another month. Thus, the applicability of this nonaqueous InHCF counterelectrode system to ECDs was verified.

Influence of coloring voltage on the optical performance and cycling stability of a polyaniline–indium hexacyanoferrate electrochromic system

An electrochromic system based on the multielectrochromic polyaniline (PANI) and pseudo-transparent indium hexacyanoferrate (InHCF) thin-film electrodes was studied in this work. In combination with a hybrid H +/K +-conducting solid polymer electrolyte—KCl-doped poly(2-acrylamido-2-methylpropanesulfonic acid) (K-PAMPS), a precoloring-free PANI–InHCF electrochromic device (ECD) with an active area of 3×3 cm 2 was fabricated and exhibited yellowish-green-blue multicolor electrochromism. From in situ spectroelectrochemical experiments, we found that the performance of a PANI/K-PAMPS/InHCF ECD was significantly affected by the operating voltages, especially by the coloring voltage. Both the bleached and yellowish state of the ECD could be attained reversibly by applying a voltage ranging from +1.5 to +1.7 V (InHCF vs. PANI). Different coloring voltages resulted in different optical properties and cycling stabilities, however. For instance, the device biased at −1.6 V (InHCF vs. PANI) showed a deep blue color, but the optical activity decayed quickly (less than 50 cycles) when the device was switched between +1.6 and −1.6 V. Nevertheless, the device could be reversibly operated between +1.6 and 0 V for several hundred cycles, although a narrower electrochromic extent (yellowish-to-green) was observed correspondingly. The optimization of the coloring voltage is therefore of paramount importance to the PANI/K-PAMPS/InHCF ECD.

Amperometric Detection of Cysteine at an In3+ Stabilized Indium Hexacyanoferrate Modified Electrode

AbstractThis research focuses on the stabilization of indium hexacyanoferrate (InHCF) modified electrode in aqueous solution and the amperometric detection of cysteine (Cys). It was found that the stability of the InHCF modified electrode in the aqueous solution could be improved upon adding In3+ in the solution. EQCM experiments verified that such an In3+ addition greatly inhibited an oxidized InHCF thin film's dissociation and thus considerably stabilizes the InHCF modified electrode. The amperometric detection was performed by the application of a static potential at 1.2 V, with the sampling time at 30 s. The sampled current was linearly dependent on [Cys] when [Cys] was ranged from 100 μM to 1 mM. The sampled current approached a plateau gradually with the increase in the concentration of cysteine. The trend of calibration curve at the InHCF modified electrode generally follows the Michaelis–Menten type kinetics, and Km and vmax were calculated to be 3.86 mM and 30.2 μA, respectively, from the Lineweaver–Burke plot. In addition, the amperometric detection was reversible and reproducible with relative standard deviations of 2.79%.

General Kinetic Model for Amperometric Sensors Based on Prussian Blue Mediator and Its Analogs: Application to Cysteine Detection

AbstractPrussian blue (PB) and its analogs, such as indium hexacyanoferrate (InHCF), can serve as artificial oxidases and mediate electron transfer from electrodes to analytes rapidly. Hence they are playing a growing role in the biosensor field. To gain further insight into the PB‐based amperometric sensors, a general kinetic model for the prediction of sensing current has been developed in this work. The model takes both effects of analyte diffusion and electrocatalytic reaction into consideration and defines a dimensionless system constant, θ°, in order to compare the surface catalytic rate with the analyte diffusion rate. Consequently, the mathematical expression of sensing current, I, is derived as follows:

Indium hexacyanoferrate films, voltammetric and impedance characterization

Charge transfer processes within indium hexacyanoferrate (InHCF) films have been studied by using mainly cyclic voltammetry and faradaic impedance methods. Cyclic voltammetry reveals the existence of two types of InHCF films deposited from solutions of high and low potassium concentrations, respectively. The difference in the electrochemical behavior of these films disappears after their cyclic processing in the range of electrode potentials from 0.0 to 1.3 V with respect to Ag/AgCl electrode. The obtained data are strongly dependent on the nature of supporting electrolyte cations. However, in all the cases, the obtained impedance spectra are qualitatively the same. In the region of high a.c. frequencies, they contain a semi-circular part, the parameters of which depend on both the substrate nature and the mechanical pre-treatment (polishing) of the used substrate (platinum, glassy carbon). This allows one to assign that part of impedance spectra to the film/electrode interface. The next part of the spectra corresponds to the Warburg impedance that is somewhat masked by the subsequent increase of the imaginary part of the film impedance under decreasing a.c. frequency. Effective diffusion coefficients calculated from the Warburg dependence for different supporting electrolytes change their values in the series: D K+≥ D Na+≫ D Li+. Such a great difference between D Li+ and D K+≥ D Na+ is confirmed by the results of chronoamperometric measurements. It is assumed that the above difference originates from different binding of the compared counter-ions with anion film fragments. This assumption is in agreement with the results derived from low frequency parts of the impedance spectra.

An indium hexacyanoferrate–tungsten oxide electrochromic battery with a hybrid K +/H +-conducting polymer electrolyte

Electrochromic tungsten oxide (WO 3) and indium hexacyanoferrate (InHCF) thin-film electrodes, in combination with a polymer electrolyte that accommodates conduction of both K + and H +, were assembled into a thin-film electrochromic battery (ECB). A typical InHCF–WO 3 ECB (designated as IWECB) can be charged and discharged reversibly between 0.5 and 1.5 V with a theoretical voltage of around 1.24 V. A hybrid K +/H +-conducting solid polymer electrolyte (SPE) was prepared through doping different amounts of KCl into poly-2-acrylamido-2-methylpropane sulfonic acid (PAMPS). The resultant SPE fulfilled the dual requirements: H + for the WO 3 and K + for the InHCF insertion/extraction. The KCl-doping level, evaluated from the molar ratio of (KCl)/(AMPS), plays a crucial role in determining the SPE properties, including its ionic conductivity and water content, and thus strongly affects the charge–discharge characteristics of the IWECB. Furthermore, both properties of the SPE exhibited a very similar, concave-up dependence on the doping level, and a minimum existed at (KCl)/(AMPS)=0.44. It was found that the SPE with a higher KCl-doping level could achieve a larger discharge capacity and a higher cell voltage, but would result in a poorer cycle life. Although the charge capacity of the IWECB was limited, it is enough to drive many low-watt electronic devices for several hours. Finally, the capability of the IWECB was also demonstrated by storing solar energy and by visualizing the state-of-charge (SOC), in which a highly contrasting blue-to-colorless electrochromism in response to discharging was visualized.

Switching behavior of the Prussian blue–indium hexacyanoferrate electrochromic device using the K +-doped poly-AMPS electrolyte

Upon sandwiching a K +-doped solid polymer electrolyte (SPE) in between the Prussian blue (PB) and indium hexacyanoferrate (InHCF) thin films, a precoloring-free electrochromic device (ECD), undergoing reversible blue-to-yellowish electrochromism when charged, was fabricated and studied. The K +-doped SPE was prepared through dissolving KCl into the monomer solution of 2-acrylamido-2-methylpropane sulfonic acid (AMPS), which was then polymerized to form the KCl-doped poly-AMPS (PAMP). It was demonstrated that this ECD shows better at-rest stability than a precolored system. Also, it was found that the KCl doping level of SPE (defined by the molar ratio of KCl to AMPS, (KCl)/(AMPS)) affects the electrochemical behaviors of PB and InHCF in different ways. Thus, the KCl doping level was optimized for attaining ECD's best performances. It was found that the widest transmittance window, fastest response, and highest coloration efficiency are obtained when (KCl)/(AMPS)=0.220, while it is the saturated doping level leads to the longest cycle life. In brief, this work aims at optimizing the design on the K +-SPE-based PB–InHCF ECD.

Modified electrode approaches for nitric oxide sensing

Three different methods for the determination of nitric oxide (NO) in solution are described. These are based, respectively, on the use of a horseradish peroxidase (HRP) biosensor or on electrodes modified with films of redox-active transition metal complexes. In the case of the biosensor the enzyme was electrochemically immobilized onto a glassy carbon (GC) electrode. The activity of HRP is inhibited in presence of NO. Thus, the decrease in activity is correlated to the concentration of NO present in solution. The biosensor responds linearly over the range of 2.7×10 −6–1.1×10 −5 M NO with a detection limit (5% inhibition) of 2.0×10 −6 M. In the case of chemically modified electrodes, particular emphasis is placed on materials capable of catalyzing the oxidation of NO. In terms of electrocatalyst, the discussion will centre on electrodeposited films of 6,17-diferrocenyldibenzo[ b, i]5,9,14,18-tetraaza[14]annulen]-nickel(II) and indium(III) hexacyanoferrate(III). The resulting sensors exhibited potent and persistent electroacatalytic activity towards the oxidation of NO with low detection limits (1 μM) and good linear relationship between the catalytic current and NO concentrations. In addition, interference due to the presence of nitrate and nitrite have been significantly reduced. According to these results, the described modified electrodes have been used as sensors for the determination of NO generated by decomposition of a typical NO-donor, such as S-nitroso- N-acetyl- d, l-penicillamine (SNAP). A critical comparison of the various methodologies employed is made.

Impedance of Indium(III) Hexacyanoferrate Films: Effect of the Supporting-Electrolyte Cation

Films of indium(III) hexacyanoferrate are studied in nitrate solutions of lithium, sodium, potassium, and ammonium using cyclic voltammetry and faradaic impedance. Effect of the supporting-electrolyte cation on parameters of the equivalent circuit corresponding to the impedance spectra is analyzed. The charge transport at the electrode/film interface is shown to be slow. The cation bonding in a film is discussed.

Electrocatalytic oxidation of nitric oxide at indium hexacyanoferrate film-modified electrodes.

The electrocatalytic oxidation of nitric oxide (NO) by indium (III) hexacyanoferrate (III) films has been studied. These films are electrodeposited onto glassy carbon electrodes through potential cycling in acidic solutions containing a potassium electrolyte, indium (III), and potassium hexacyanoferrate. The resulting modified electrodes exhibit a reversible redox response ascribed to the oxidation/reduction of iron atoms presents in the electrodeposited film. The films have a potent and persistent electrocatalytic activity towards NO oxidation at neutral pH. The electrocatalytic oxidation of NO takes place at potentials around +0.75 V which represents a moderate diminution in the overpotential. In addition, interferences due to the presence of nitrate and nitrite have been significantly reduced. According to these results, the described modified electrodes have been used as sensors for the determination of NO generated by decomposition of a typical NO-donor, such as S-nitroso- N -acetyl- d, l -penicillamine (SNAP).

A complementary electrochromic system based on Prussian blue and indium hexacyanoferrate

A new complementary electrochromic device (ECD) based on Prussian blue (PB), indium hexacyanoferrate (InHCF), and KCl-saturated poly(2-acrylamido-2-methylpropanesulfonic acid) (K-PAMPS) was proposed and studied in this work. This novel PB-InHCF ECD (PIECD) exhibits blue-to-yellowish electrochromism with a high coloration efficiency of ca. 103 cm2/C at 690 nm. Although the operating voltages for the fully bleached and fully colored states were determined to be 1.2 V and 0 V (InHCF vs. PB), respectively, the major transmittance modulation occurs within a much narrower voltage window (0.9 V↔0.5 V). That is, the PIECD is energetically favorable. Furthermore, it is unnecessary to precolor either electrochromic (EC) electrode during the cell assembly so that the charge balance between two electrochromic films becomes much easier. In addition to the above performance, the compatibility between the K-PAMPS electrolyte and EC electrodes was also demonstrated. In short, this work proposes another promising PB-based ECD and provides a new choice in the EC field.