Copper Hexacyanoferrate Research Articles

A novel electrochemical sensor based on dual-functional MMIP-CuMOFs for both target recognition and signal reporting and its application for sensing bisphenol A in milk

In this work, novel magnetic molecularly imprinted CuMOFs (MMIP-CuMOFs) were synthesized and applied to construct an electrochemical bisphenol A sensor. The constructed sensor used an electrode modified with reduced graphene oxide (RGO/GCE) as the sensing platform to improve its stability and sensitivity. The Fe3O4 nanoparticles in magnetic MOFs simplified the preparation process. Moreover, the combination of CuMOFs and molecular imprinting methodology was beneficial for improving the detection specificity, and the electroactive copper hexacyanoferrate generated by the reaction of Cu2+ in CuMOFs with potassium ferricyanide was used as the signal probe. The sensor showed a good linear relationship in the range of 0.5 to 500 nmol/L, with a low detection limit of 0.18 nmol/L. In addition, the sensor had good selectivity, repeatability (RSD = 2.59 %), and a good recovery rate for actual milk sample detection (99.8–102.49 %). This technique holds great promise for the detection of detrimental substances in food.

Constructing DNAzyme-driven three-dimensional DNA nanomachine-mediated paper-based photoelectrochemical device for ultrasensitive detection of miR-486-5p

As a unique class of dynamic nanostructures, biomimetic DNA walking machines that exhibit geometrical complexity and nanometre precision have gained great success in photoelectrochemical (PEC) bioanalysis. Despite certain achievements, the slow reaction kinetics and low processivity severely restrict the amplification efficiency of the DNA walker-mediated biosensors. Herein, by taking advantage of efficient DNA rolling machines, a three-dimensional (3D) DNA nanomachine-mediated paper-based PEC device for speedy ultrasensitive detection of miR-486–5p was successfully constructed. To achieve it, a novel In2S3/SnS2 sensitized heterojunction was firstly in-situ grown on the Au-modified paper fibers and implemented as the photoanode with effective separation of photogenerated carriers to achieve an enhanced initial photocurrent. Subsequently, the copper hexacyanoferrate(II)-modified CuO nanosphere was introduced as a multifunctional signal regulator via the competitive capture of electron donors and photon energy with the photoelectric layer for efficiently quenching the PEC signal. With the introduction of targets, the DNAzyme-driven DNA nanomachine with editable motion modes was gradually activated and it could continuously cleave the tracks DNA labeled quenching probes, finally achieving the recovery of PEC signal. As a proof of concept, the elaborated paper-based PEC device presented a wide linear range from 0.1 fM to 100 pM and a detection limit of 35 aM for miR-486–5p bioassay. This work provides an innovative insight to the exploitation of DNA nanobiotechnology and nucleic acid signal amplification strategy.

Chemically synthesized cobalt oxide incorporated copper hexacyanoferrate (Co3O4–CuHCF) composite as an efficient supercapacitor electrode material

Chemically synthesized cobalt oxide incorporated copper hexacyanoferrate (Co3O4–CuHCF) composite as an efficient supercapacitor electrode material

Facile synthesis of polydopamine-interlinked titanate nanosheets and copper hexacyanoferrate for highly efficient removal of Cs(I)

Facile synthesis of polydopamine-interlinked titanate nanosheets and copper hexacyanoferrate for highly efficient removal of Cs(I)

Synthesis and Investigation of the Properties of Biphasic Hybrid Composites Based on Bentonite, Copper Hexacyanoferrate, Acrylamide and Acrylic Acid Hydrogel.

This article presents a study of the synthesis and characterization of new biphasic hybrid composite materials consisting of intercalated complexes (ICC) of natural mineral bentonite with copper hexaferrocyanide (phase I), which are incorporated into the bulk of the polymer matrix (phase II). It has been established that the sequential modification of bentonite with copper hexaferrocyanide and introduction of acrylamide and acrylic acid cross-linked copolymers into its volume by means of in situ polymerization promote the formation of a heterogeneous porous structure in the resulting hybrid material. The sorption abilities of prepared hybrid composite toward radionuclides of liquid radioactive waste (LRW) have been studied, and the mechanism for binding radionuclide metal ions with the components of the hybrid composition have been described.

Ultrafast Nucleation Reverses Dissolution of Transition Metal Ions for Robust Aqueous Batteries.

The dissolution of transition metal ions causes the notorious peeling of active substances and attenuates electrochemical capacity. Frustrated by the ceaseless task of pushing a boulder up a mountain, Sisyphus of the Greek myth yearned for a treasure to be unearthed that could bolster his efforts. Inspirationally, by using ferricyanide ions (Fe(CN)63-) in an electrolyte as a driving force and taking advantage of the fast nucleation rate of copper hexacyanoferrate (CuHCF), we successfully reversed the dissolution of Fe and Cu ions that typically occurs during cycling. The capacity retention increased from 5.7% to 99.4% at 0.5 A g-1 after 10,000 cycles, and extreme stability of 99.8% at 1 A g-1 after 40,000 cycles was achieved. Fe(CN)63- enables atom-by-atom substitution during the electrochemical process, enhancing conductivity and reducing volume change. Moreover, we demonstrate that this approach is applicable to various aqueous batteries (i.e., NH4+, Li+, Na+, K+, Mg2+, Ca2+, and Al3+).

High-efficiently and rapidly capturing cesium from water with Prussian blue@expanded graphite as adsorbent

The removal of radioactive 137Cs from nuclear wastewater is still needed to mitigate their high radiological toxicity to living creatures. However, the industrial application of adsorbents is still challenging owing to the complex and costly preparation and slow adsorption rate for Cs wastewater with low concentration. Herein, cost-effective and fast removal of Cs+ is achieved by vermiform expanded graphite (EG) immobilized with potassium copper hexacyanoferrate (KCuHCF) via the in-situ synthesis method. We revealed that the nano-scale KCuHCF granules are dispersed homogeneously on the EG interlayers. With this design, it achieves an excellent Cs removal capacity of 16.24 mg/g within 30 min in ultralow Cs concentration and shows high selectivity among various competing ions. We systematically studied the associated adsorption mechanism by XPS and ICP, which revealed that ion exchange between the lattice K and Cs played critical roles. Our work paves the way for the design of economical adsorbents for radioactive Cs remediation.

CNT/copper hexacyanoferrate: A superior Faradic electrode for ammonium ion removal with stable performance and high capacity

The discharge of ammonium ion (NH4+) not only seriously threatens the ecological safety of the environment, but also causes the waste of valuable resources. Capacitive deionization (CDI) is an environmentally friendly and efficient NH4+ ion treatment and recovery technology. Herein, the NH4+-rich copper hexacyanoferrate (N-CuHCF) and carbon nanotube (CNT) complex (CNT/N-CuHCF) was formed by a simple and fast co-precipitation-ion exchange method, and used as the Faradic electrode to store NH4+ in the hybrid capacitive deionization (HCDI) system. Intriguingly, the etching efficiency of the ion exchange process produces the interconnected nanonetwork structure, endows the prepared material with larger surface area and abundant redox active sites, guarantees high pseudocapacitance contribution and reversible NH4+ intercalation/deintercalation, thus enabling an excellent ammonium ion removal performance. The CNT/N-CuHCF demonstrates a superior specific adsorption capacity (SAC) of 120.2 mg g−1, a low specific energy consumption (126.1 kJ molNH4Cl−1), and remarkable cycling stability. In addition, compared with Na+ and Mg2+, CNT/N-CuHCF has better affinity and selectivity for NH4+. The NH4+ intercalation mechanism and structure stabilization mechanism of N-CuHCF were revealed through a series of ex situ characterizations. This work provides some new illuminating insights for the design of high-performance ammonium ion removal CDI electrodes, and lays a foundation for the recovery of ammonium resources.

Cation Co-intercalation in Potassium Copper(II) Hexacyanoferrates.

The cation-insertion solid state electrochemistry of a potassium copper(II) hexacyanoferrate in contact with LiClO4 /DMSO, NaPF6 /DMSO, and KPF6 /DMSO electrolytes has been theoretically and experimentally studied using the voltammetry of immobilized particles methodology. Voltammetric data, combined with SEM/EDS analysis permit to determine a K0.876 CuII 1.328 FeIII 0.049 [FeIII 0.318 FeII 0.682 (CN)6 ] stoichiometry for the synthesized solid. Separation of electronic and ionic contributions to Gibbs energy changes can be made based on cyclic voltammetric and open circuit potential measurements. These parameters can be combined to measure values of the Gibbs energy of cation-independent electron transfer of 7.2±0.4 (K+ ), 7.1±0.5 (Na+ ) kJ mol-1 , in close agreement with the expected independence of this parameter on the electrolyte cation. The reduction Fe(III) centers bound to cyano groups exhibit a cation-dependent, essentially Nernstian character which can be described in terms of Na+ and K+ insertion/deinsertion while in the case of Li+ electrolytes there is significant co-cation diffusion. Chronoamperometric data provide estimates of the diffusion coefficients of Na+ , and K+ ions through the solid around 10-9 cm2 s-1 .

Preintercalated Copper Hexacyanoferrate as a Long-Time Cycle Cathode Material for Aqueous Aluminum-Ion Batteries

Preintercalated Copper Hexacyanoferrate as a Long-Time Cycle Cathode Material for Aqueous Aluminum-Ion Batteries

In Situ Continuous Measurement of Salinity in Estuarine and Coastal Sediments by All-Solid Potentiometric Sensors

Salinity is crucial for understanding the environmental and ecological processes in estuarine and coastal sediments. In situ measurements in sediments are scarce due to the low water content and particulate adsorption. Here, a new potentiometric sensor principle is proposed for the real-time in situ measurement of salinity in sediments. The sensor system is based on paper sampling and two all-solid electrodes, a cation-selective electrode (copper hexacyanoferrate, CuHCF) and an anion-selective electrode (Ag/AgCl). The spontaneous aqueous electrolyte extraction and redox reaction can produce a Nernstian response on both electrodes that is directly related to salinity. This potentiometric sensor allows for salinity acquisition in a wide salinity range (1-50 ppt), with high resolution (<1 ppt), and at a low water content (<30%), and it has been applied for the in situ measurement of salinity and the interpretation of cycling processes of metals in estuarine and coastal sediments. Moreover, the sensor coupled to a wireless monitoring system exhibited remote-sensing capability and successfully captured the salinity dynamic processes of the overlying water and pore water during the tidal period. This sensor with its low cost, versatility, and applicability represents a valuable tool to advance the comprehension of salinity and the salinity-driven dissolved-matter variations in estuarine and coastal sediments.

Influence of the Thermal Treatment on the Structure and Cycle Life of Copper Hexacyanoferrate for Aqueous Zinc-Ion Batteries

Copper hexacyanoferrate (CuHCF) has become an attractive Zn2+ insertion material as a positive electrode in aqueous zinc-ion batteries thanks to its high reversibility towards Zn2+ (de-)insertion, its simple, inexpensive and easily scalable synthesis route, its low toxicity, and its high working potential. It is known that the physiochemical properties of CuHCF can be modified by manipulating its synthesis parameters. However, the effect of these parameters on the material’s electrochemical performance and cycle life needs further investigation. Here, the structure and composition of CuHCF treated at different temperatures are studied through crystallographic, compositional, and thermogravimetric analyses. The resulting CuHCF powders were galvanostatically cycled to assess their electrochemical performance in relation to their annealing temperature. The results showed that the annealed CuHCF electrodes exhibited longer cycle life while maintaining a coulombic efficiency ≥ 99.5%. The longest cycle life was achieved by annealing the CuHCF electrodes at 100 °C.

Enzyme-Regulated In Situ Formation of Copper Hexacyanoferrate Nanoparticles with Oxidase-Mimetic Behaviour for Colorimetric Detection of Ascorbate Oxidase.

In this study, a copper hexacyanoferrate nanoparticle with excellent oxidase-mimetic behaviour has been synthesized through a simple precipitation method. The synthesized copper hexacyanoferrate nanoparticle has intrinsic oxidase-like activity, which can catalyze the chromogenic reaction of 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) through an O2•- reactive oxygen-species-participated process. On the other hand, K3[Fe(CN)6] can be reduced by ascorbic acid (AA) to produce K4[Fe(CN)6], thereby inhibiting the formation of the copper hexacyanoferrate nanoparticles. Furthermore, ascorbate oxidase (AAO) can catalyze the oxidation of AA to produce dehydroascorbic acid, which cannot reduce K3[Fe(CN)6]. Thus, a system for an AAO-regulated in situ formation of copper hexacyanoferrate nanoparticles was constructed by coupling a prepared copper hexacyanoferrate nanozyme with AA for the detection of AAO activity. This colorimetric sensing assay shows high sensitivity and selectivity for the detection of AAO activity (the limit of detection is 0.52 U/L) with a linear range of 1.1-35.7 U/L. Finally, the developed method was applied to detect the activity of AAO in normal human serum with a satisfactory sample spiked recovery (87.4-108.8%). In short, this study provides a good strategy for the construction of nanozyme-based multi-enzyme cascade-signal amplification assay.

An experimental and theoretical approach to electrochemical sensing of hydrazine at silver and copper hexacyanoferrates electrodes

This work evaluates the electrocatalytic oxidation of hydrazine (HDZ) by silver (AgHCF) and copper (CuHCF) hexacyanoferrates-modified glassy carbon electrodes kinetically and analytically through experimental electrochemistry and theoretical approaches. The materials were prepared by a two-step cyclic voltammetry (CV) routes and had their structural and morphological attributes attested by microscopic and spectroscopic characterization techniques. The AgHCF and CuHCF-modified electrodes showed quasi-reversible characteristics driven by K+ diffusion and adsorption processes, respectively. The kinetic properties of the materials towards HDZ electrooxidation were evaluated through CV and chronoamperometry techniques. The analyte exhibited irreversible electron transfer controlled by semi-infinite diffusion process for both Prussian blue analogs. The CuHCF-modified electrode showed superior diffusion coefficient (D = 2.17×10−5 cm2 s−1) and catalytic rate constant (kcat = 1.75×103 L mol−1 s−1) comparing to the silver analog (D = 2.31×10−6 cm2 s−1 and kcat = 8.06×102 L mol−1 s−1). The copper-based material also exhibited higher sensitivity (S) obtained through CV (S = 42 nA L µmol L−1) and batch injection analysis-coupled amperometry (BIA/amp) (S = 66.8 nA L µmol L−1) measurements, in comparison to AgHCF-modified electrode (S = 25 nA L µmol L−1 – CV; S = 22.3 nA L µmol L−1 – BIA/amp). Theoretical approaches showed that CuHCF material required lower energy (ΔEgap = 0.0397 eV) to promote an electron to the lowest unoccupied molecular orbital due to its cubic structural arrangement, justifying the better electrocatalytic results comparing to the hexagonal structure of the AgHCF material (ΔEgap = 0.0840 eV).

Reversible aqueous aluminum metal batteries enabled by a water-in-salt electrolyte

Aluminum (Al), the most abundant metallic element on the earth crust, has been reckoned as a promising battery material for its the highest theoretical volume capacity (8046 mAh cm−3). Being rechargeable in ionic liquid electrolytes, however, the Al anode and battery case suffer from corrosion. On the other hand, Al is irreversible in aqueous electrolyte with severe hydrogen evolution reaction. Here, we demonstrate a water-in-salt aluminum ion electrolyte (WISE) based on Al and lithium salts to tackle the above challenges. In the WISE system, water molecules can be confined within the Li+ solvation structures. This diminished Al3+-H2O interaction essentially eliminates the hydrolysis effect, effectively protecting Al anode from corrosion. Therefore, long-term Al plating/stripping can be realized. Furthermore, two types of high-performance full batteries have been demonstrated using copper hexacyanoferrate (CuHCF, a Prussian Blue Analogues) and LiNi0.8Co0.1Mn0.1O2 (NCM) as cathodes. The reversibility of Al anode laid the foundation for low cost rechargeable batteries suffering for large-scale energy storage.Broader context: Al batteries are expected to become a safe and sustainable alternative to lithium batteries. For decades, chase for a feasible Al secondary battery has not been successful. The key challenge is to find suitable cathode and electrolyte materials, together with which Al anode battery can function reversibly. Currently, fatal drawbacks have impeded the practical application of Al metal batteries (AMBs), such as sustained corrosion of Al anode and battery case in ionic liquid electrolytes, irreversibility issues as well as severe hydrogen evolution reaction during cycling in aqueous electrolyte. Therefore, electrolyte and their electrochemical kinetics play a vital role in the performance and environmental operating limitations of high-energy Al metal batteries. In this work, we demonstrate a nearly neutral Al ion water-in-salt electrolyte (WISE) to tackle the above challenges. The WISE shows excellent stability in the open atmosphere. The distinct solvation-sheath structure of Al3+ in the WISE system would protect Al metal anodes from corrosion and eliminate hydrogen evolution reaction effectively, further promoting the reversibility of Al metal anodes with dendrite-free morphology. Moreover, such a WISE exhibits superior compatibility with LiNi0.3Co0.3Mn0.3O2 (NCM) and copper hexacyanoferrate (CuHCF) cathodes and long-term stabilities with high coulombic efficiency (CE) can be attained for full batteries with the WISE. The approach in this study can furnish an opportunity to develop reversible AMBs and lay the foundation for other potential multivalent-metal-based secondary batteries suffering from interface passivation and poor reversibility, which suggest the promise of multivalent metal batteries and their applications in large-scale energy storage.

Synergistic Effect of Iron and Copper Oxides in the Removal of Organic Dyes Through Thermal Induced Catalytic Degradation Process

This study proposes a new method for producing α-Fe2O3–CuO nanocatalyst that is both cost-effective and ecologically benign. The α-Fe2O3–CuO nanocomposite was prepared via moderate thermal oxidative decomposition of copper hexacyanoferrate. Its structure and surface morphology are affirmed via XRD, SEM, FTIR, EDX, TEM, XPS, and VSM. In the presence of H2O2, α-Fe2O3–CuO is employed as a heterogeneous catalyst to stimulate thermally induced degradation of dyes such as direct violet 4, rhodamine b, and methylene blue. The synergistic effect of Fe2O3 and CuO enhanced the catalytic activity of the nanocomposite compared to Fe2O3 and CuO separately. The effectiveness of DV4 degradation is optimized by evaluating multiple reaction parameters. The reaction rate increased substantially with the temperature, revealing its key role in the degradation process. Higher H2O2 levels and the inclusion of inorganic anions like chloride or nitrate also sped up the degradation process. While sulfate and humic acid, particularly at high doses, slowed it. The mechanism of H2O2 activation on α-Fe2O3–CuO is studied. The measurements of chemical oxygen demand and total organic carbon indicate that all dyes are highly mineralized. The remarkable performance and stability of this nanocomposite in removing diverse dyes render it a promising option for wastewater remedy.

Rechargeable sodium-ion battery based on a cathode of copper hexacyanoferrate

Rechargeable sodium-ion battery based on a cathode of copper hexacyanoferrate

Soft-hard interface design in super-elastic conductive polymer hydrogel containing Prussian blue analogues to enable highly efficient electrochemical deionization.

The poor cycling stability of faradaic materials owing to volume expansion and stress concentration during faradaic processes limits their use in large-scale electrochemical deionization (ECDI) applications. Herein, we developed a "soft-hard" interface by introducing conducting polymer hydrogels (CPHs), that is, polyvinyl alcohol/polypyrrole (PVA/PPy), to support the uniform distribution of Prussian blue analogues (e.g., copper hexacyanoferrate (CuHCF)). In this design, the soft buffer layer of the hydrogel effectively alleviates the stress concentration of CuHCF during the ion-intercalation process, and the conductive skeleton of the hydrogel provides charge-transfer pathways for the electrochemical process. Notably, the engineered CuHCF@PVA/PPy demonstrates an excellent salt-adsorption capacity of 22.7 mg g-1 at 10 mA g-1, fast salt-removal rate of 1.68 mg g-1 min-1 at 100 mA g-1, and low energy consumption of 0.49 kW h kg-1. More importantly, the material could maintain cycling stability with 90% capacity retention after 100 cycles, which is in good agreement with in situ X-ray diffraction tests and finite element simulations. This study provides a simple strategy to construct three-dimensional conductive polymer hydrogel structures to improve the desalination capacity and cycling stability of faradaic materials with universality and scalability, which promotes the development of high-performance electrodes for ECDI.

Investigating the role of interstitial water molecules in copper hexacyanoferrate for sodium-ion battery cathodes

The electrochemical performance of prussian blue analogues (PBAs) can be determined by the number of interstitial water molecules in the channels, which inhibits the insertion and diffusion of sodium-ions in an aqueous electrolyte system.

Magnetic copper hexacyanoferrate core–shell nanoparticles for effective cesium removal from aqueous solutions

Selective and efficient removal of Cs+ ion by CuHCF@Fe3O4 nanoparticles and their regeneration can be controlled by modulating the redox state of CuHCF on Fe3O4 nanoparticles. The CuHCF@Fe3O4 nanoparticles can be easily recollected by magnet.