Bimetallic Prussian Blue Analogue Research Articles

Electrically Detectable Photoinduced Polarization Switching in a Molecular Prussian Blue Analogue.

Light, a nondestructive and remotely controllable external stimulus, effectively triggers a variety of electron-transfer phenomena in metal complexes. One prime example includes using light in molecular cyanide-bridged [FeCo] bimetallic Prussian blue analogues, where it switches the system between the electron-transferred metastable state and the system's ground state. If this process is coupled to a ferroelectric-type phase transition, the generation and disappearance of macroscopic polarization, entirely under light control, become possible. In this research, we successfully executed a nonpolar-to-polar phase transition in a trinuclear cyanide-bridged [Fe2Co] complex crystal via directional electron transfer. Intriguingly, by exposing the crystal to the wavelength of light─785 nm─without any electric field─we can drive this ferroelectric phase transition to completely depolarize the crystal, during which a measurable electric current response can be detected. These discoveries signify an important step toward the realization of fully light-controlled ferroelectric memory devices.

Size regulated N-doped carbon encapsulated NiFe alloys/Ni phosphide composites derived from bimetallic Prussian blue analogues for effective microwave absorption

Prussian blue analogues (PBAs) derivatives have emerged as microwave absorbing materials to address electromagnetic pollution in recent years. In this work, bimetallic NiFe-PBA derived multi-interface N-doped carbon (NC) encapsulated NiFe alloys/Ni phosphide composites (NFPC) were prepared by thermal treatment and phosphating process. The PBAs samples with different chemical compositions and particle sizes were synthesized by manipulating the proportions of raw materials. The particle sizes of PBAs significantly impact the morphology, phosphating degree and electromagnetic properties of the NFPC composites. The results indicated that the NFPC composites exhibit excellent microwave absorption performance, with a minimum reflection loss of −41.4 dB at 1.36 mm and the effective absorption bandwidth of 4.4 GHz at 1.34 mm. The corresponding microwave attenuation mechanisms of NFPC composites were further investigated. This study not only presents a comprehensive investigation into the controlled growth of PBAs, but also provides innovative design strategies and valuable insights on utilizing multiple interfacial magnetic alloys/phosphides@NC composites as efficient microwave absorbing materials.

An innovative dual-signal electrochemical ratiometric determination of creatinine based on silver nanoparticles with intrinsic self-calibration property for bimetallic Prussian blue analogues.

An ultrasensitive dual-signal ratiometric electrochemical sensor was developed for creatinine detection utilizing silver nanoparticles (Ag) with intrinsic self-calibration afforded by iron-nickel bimetallic Prussian blue (FeNiPBA) analogues. The Ag@FeNiPBA exhibits two redox signals corresponding to the Ag+/Ag and Fe3+/Fe2+ systems. Adding chloride (Cl-) solution increases the anodic current of the Ag/Ag system significantly due to the formation of silver chloride through solid-state electrochemistry. While the anodic current of the Ag/Ag system decreases in the presence of creatinine due to the competitive reaction, the Fe/Fe system's anodic current remains the same, which enables a ratiometric response. Under optimized conditions, the response ratio (IAg/IFe) decreases while the creatinine concentration increases linearly between 0.015 and 140 μM, with 0.004 μM as a good detection limit (S/N = 3). These results demonstrate superior performance over previously reported methods for electrochemical creatinine determination. The high sensitivity arises from the signal amplification of the Ag/AgCl solid-state electrochemistry, while the selectivity originates from the specific interaction between Ag+ and creatinine. The Ag@FeNiPBA hybrid can quantify creatinine in real samples with good recoveries. This work opens up new opportunities for applying dual-signal nanostructures to develop electrochemical sensors for (bio)molecule detection.

Prussian blue analogue derived 3D hollow LiCoMnO4 nanocube for selective extraction of lithium by pseudo-capacitive deionization

Facing the huge demand of lithium resources in the green energy-oriented international development, the electrochemical lithium extraction technology is becoming one of the most popular way for lithium recovery from salt-lake brine or seawater. In this work, a novel LiCoMnO4 (LCMO) nanocube was facilely obtained by one-pot synthesis in the presence of Mn,Co-based bimetallic Prussian blue analogue (MnCo-PBA) and LiOH. The well-defined LCMO nanocube with unique hollow three-dimensional (3D) configuration was composed of small spinel structural LCMO nanocrystals with the particle size of 150 nm. In contrast with the LCMO block material, the specific surface area of LCMO nanocube increased, and the corresponding electrochemical activity enhanced significantly. As a Li+-selective cathode in capacitive deionization (CDI) device, LCMO nanocube exhibited high selectivity for Li+ extraction with excellent cycling stability. The Li+ adsorption amount achieved 700 μmol g−1, with the separation factor αMg2+Li+ of 88.7 (CMg2+/CLi+ = 30). The LCMO-based pseudo-CDI system was proved to be effective for Li+ extraction from the real salt-lake brine. This study delivered a new strategy for constructing a 3D porous Li+-intercalation material for Li recovery and beyond.

Tailoring abundant active-oxygen sites of Prussian blue analogues-derived adsorbents for highly efficient Yb(III) capture.

The removal of rare earth elements in mineral processing wastewater is highly desirable but still challenging. In this study, three bimetallic Prussian blue analogues (PBA) and six corresponding oxides are prepared by co-precipitation and calcination methods, and then utilized to adsorb aqueous Yb(III) solution. The results of XRD, SEM, BET, and XPS indicate the successful synthesis of all the adsorbents. Among them, three PBA-oxide samples (PBO-800) exhibit the superior adsorption capacities (˃250mg/g). The adsorption processes of Yb(III) are in accordance with the pseudo-second-order kinetic model and Langmuir model, simultaneously showing the spontaneous and endothermic thermodynamics. Moreover, PBO-800 can be reused after alkaline solution regeneration with less than 10% degradation after five consecutive adsorption-desorption cycles. More importantly, PBO-800 exhibits the impressive separation selectivity of Yb(III) and most light rare earth ions (e.g., 5.51 of Yb/La, 4.03 of Yb/Pr), as well as the selectivity of Yb(III) and alkali metal ions (e.g., 300.5 of Yb/Na, 256.2 of Yb/Ca). According to the characterization analysis and DFT calculation, the adsorption mechanism of Yb(III) by PBO-800 is mainly attributed to the strong interaction between the abundant active-oxygen sites and Yb(III), and the significant electrostatic attraction.

Tuning the Fe/Co ratio towards a bimetallic Prussian blue analogue for the ultrasensitive electrochemical sensing of 5-hydroxytryptamine

Lack of highly efficient, inexpensive, and easily available catalysts severely limits the practical applicability of electrochemically sensing assay towards 5-hydroxytryptamine (5-HT). Herein, four kinds of Fe–Co bimetallic Prussian blue analogues (FeCo–PBAs) with different molar ratios of Fe to Co were prepared using a simple coprecipitation method. Interestingly, Fe(III) in K3 [Fe(CN)6] can be reduced to Fe(II) by adding trisodium citrate dehydrate, which could offer a new clue to synthesize PBAs with Fe(II) core ions. With the optimizational FeCo-PBA synthesized at a 0.5/1 M ratio of Fe to Co as an electrocatalyst, the constructed sensor shows excellent comprehensive performance for the 5-HT assay with a high sensitivity of 0.856 μA μM−1 and an ultralow detection limit of 8.4 nM. Under the optimum conditions, linearity was obtained in the ranges of 0.1–10.0 μM and 10.0–200.0 μM and preferable recoveries ranged from 97.8% to 103.0% with relative standard deviation (RSD) < 4.0%. The integrated properties of FeCo-PBA can be comparable to previously reported electrocatalysts for the 5-HT assay including noble metal-based and expensive carbon (graphene and carbon nanotubes)-based electrocatalysts. The proposed sensor also exhibits outstanding selectivity, reproducibility, and practicality for real sample analyses. This work is the first report on the PBA-based sensor for the 5-HT assay, verifying the practicability of this high-performance sensor for the 5-HT assay.

Dilute Hybrid Electrolyte for Low-Temperature Aqueous Sodium-Ion Batteries.

A hybrid electrolyte based on low-concentration sodium nitrate with glycerol as an additive was proposed for aqueous sodium-ion batteries (ASIBs) towards low-temperature performance. Based on this dilute hybrid electrolyte and configured by bimetallic Prussian blue analogue (Ni2 ZnHCF) cathode and 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) anode, the full cell demonstrated surprising cycle performance with a specific capacity of 60 mAh g-1 (>800 cycles) and achieved prominent performance at low temperature. Glycerol effectively expanded the electrochemical stability window of the hybrid electrolyte to 2.7 V from formation of strong hydrogen bonds with water molecules and realized the operation of the cell at low temperature, delivering a stable reversible capacity of 40 mAh g-1 at -10 °C. The hybrid electrolyte of glycerol-water provides a new alternative in development of low-cost, long-lifespan, and low-temperature ASIBs and other aqueous battery systems.

Trimetallic Prussian blue analogue derived FeCo/FeCoNi@NPC composites for highly efficient microwave absorption

Recently, Prussian blue analogues (PBA) have emerged as attractive precursors or templates for the construction of porous carbon-based microwave absorption (MA) materials because of their open framework, tunable components and mild synthesis conditions. Herein, for the first time, trimetallic FeCoNi-PBA nanocubes are introduced as precursors, and then a novel core-shell structured composites, in which FeCo and FeCoNi alloy nanoparticles are uniformly encapsulated in N-doped porous carbon (FeCo/FeCoNi@NPC), are successfully synthesized via a pyrolysis process. Benefiting from the strong synergetic effects among multiple components (FeCo, FeCoNi alloys and N-doped carbon species) and the hierarchical porous structure, the absorber exhibits significantly enhanced MA performance in comparison with FeNi@NPC and FeCo@NPC derived from bimetallic PBAs. Impressively, the minimum reflection loss (RL) is up to −67 dB at 14.7 GHz with a thin thickness of 1.91 mm, and the corresponding effective absorption bandwidth (EAB) reaches 6.24 GHz, covering the whole Ku-band. When the thickness is 2.05 mm, the maximum EAB of 6.6 GHz can be obtained. In particular, the absorber can also achieve full absorption of X-band at 2.68 mm. More importantly, the multi-metallic PBA derivation strategy sheds new light on development of lightweight carbon-based absorbers with high performance, low cost and easy synthesis.

Bimetallic Prussian Blue Analogues: An Efficient Electrode Alternative for Energy Storage Applications

In the past few years Prussian Blue Analogues (PBAs), as advanced metal organic framework compounds, have gathered a lot of attention due to its three-dimensional structural network and properties. PBAs are famous for their multitasking ability as they have shown an efficient role in scientific research and development with their excellent performance in various fields like, electrochemical sensors, photocatalysis, electrocatalysis, and energy storage applications. Apart from their high-tech productivity, PBAs also have some other advantages associated to them such as benign nature, economical and facile synthesis, extensive surface properties, higher theoretical capacity and exceptional electrochemical behavior which makes it more promising material for energy storage application. To further tune its properties according to the application of interest, the chemical modification by metal incorporation is the most commonly adopted strategy. For this purpose, the major research is done in the synthesis of bimetallic PBAs. The presence of metal atoms with different oxidation states can bring about dramatic reinforcements like finer microstructures with better crystallographic features, ultimately giving rise to more stable electrochemical behavior. In this article, we aim to list out all the bimetallic PBAs with focus on the synergistic effect of more than one metal within the structure of PBA and thorough analysis of their Electrochemical properties in energy storage applications.

Ultra-fast and high-stable near-pseudocapacitance intercalation cathode for aqueous potassium-ion storage

Abstract The intrinsically limited rate capability of batteries by the diffusion-controlled ionic storage mechanism is still existing, and long-service batteries are always required for low-cost grid-scale energy storage. Herein, we design and construct a series of NixZnyHCF (x + y = 3, x = 1, 1.5 or 2) bimetallic Prussian blue analogues as cathode materials for aqueous potassium-ion batteries. On the basis of electrochemical and structural analysis, a synergistic effect between stable Ni2+ and high-voltage Zn2+ in Ni2Zn1HCF is demonstrated, which simultaneously promises ultrafast near-pseudocapacitance intercalation and super-stable potassium storage. As presented, Ni2Zn1HCF cathode shows an extraordinary high-rate capability of 1000C with a capacity retention of 66% and a high capacity recovery of 95.3%, which derives from the large sufeace area and fast near-pseudocapacitive intercalation mechanism. When cycled at 1000C for 80,000 times, a negligible capacity decay of 0.000385% per cycle further proves this cathode to be high-rate and ultra-stable. In addition, the highly reversible solid-solution K+ intercalation/extraction mechanism in the Ni2Zn1HCF cathode is illustrated by the in-situ X-ray diffraction. This work presents a promising cathode for building ultrafast and long-service aqueous potassium-ion batteries.

Facile syntheses of bimetallic Prussian blue analogues (KxM[Fe(CN)6]·nH2O, M=Ni, Co, and Mn) for electrochemical determination of toxic 2-nitrophenol

In this work, three kinds of bimetallic Prussian blue analogues (PBAs), i.e. KxNi [Fe(CN)6]·nH2O (NiFe-PBA), KxCo [Fe(CN)6]·nH2O (CoFe-PBA), and KxMn [Fe(CN)6]·nH2O (MnFe-PBA), were synthesized by a simple precipitation method under identical conditions. Their chemical compositions, structures, morphologies, valences of transition metals, and electrochemical sensing performances for 2-nitrophenol (2-NP) are examined in details. It is found that all the prepared PBAs hold face-centered-cubic structures with near perfect cube morphologies for NiFe-PBA and CoFe-PBA and truncated cube morphology for MnFe-PBA. For the electrochemical detection of 2-NP, a wide detection range of 1.0–700.0 μM was obtained at all PBAs modified electrodes together with the sensitivities of 443.3, 368.0, and 339.0 μA cm−2 mM−1 and detection limits of 0.28, 0.46, and 0.59 μM achieved at NiFe-PBA, CoFe-PBA, and MnFe-PBA modified electrodes, respectively. The superiority in electrochemical sensing performance of NiFe-PBA to CoFe-PBA and MnFe-PBA may stem from its higher conductivity, lager electroactive surface area, and better intrinsic catalytic property of the transition metal in its framework. Furthermore, the constructed NiFe-PBA-based sensor displays good repeatability, long-term stability, and high selectivity together with desirable recoveries (97.8–103.9%) for the assay of 2-NP in water samples. The present work is the first report on the PBAs-based electrochemical sensors for 2-NP detection, which may promise a future of PBAs or PBAs-based materials for sensing applications.

Controlled synthesis of bimetallic Prussian blue analogues to activate peroxymonosulfate for efficient bisphenol A degradation

Developing high-effective catalysts with tailored composition and structure has attracted extensive attention. In this work, a serious of shape-specific Fe/Co Prussian blue analogs (PBAs), including concave, core-shell and polygonal cubes were prepared by the one-step hydrothermal reaction, which were altered by adjusting the ratio of Fe/Co in the initial reaction system. The catalytic performance toward bisphenol A (BPA) degradation was significantly affected by the ultimate structure and Fe/Co composition. Benefiting from appropriate elemental proportions, unique elemental distribution (rich Co in the core and rich Fe in the shell) and high specific surface areas, the core-shell PBAs (CSPs) exhibits significantly higher peroxymonosulfate (PMS) activation performance toward bisphenol A (BPA) degradation (96 % of removal efficiency within 2 min). The stability of the CSPs catalyst test further indicates that the Fe shell can effectively protect and inhibit the leaching of cobalt ions. Electron paramagnetic resonance (EPR) and radical quenching experiments measurement exhibited that both SO4− and OH are the main active species in the degradation process. Our work expanded new ideas of designing novel PBAs with controllable shape and specific core-shell composition with excellent catalytic performance.

In Situ Transformation of Prussian‐Blue Analogue‐Derived Bimetallic Carbide Nanocubes by Water Oxidation: Applications for Energy Storage and Conversion

Using bimetallic Prussian blue analogue (PBA) as a precursor is effective for preparing electrocatalysts for the oxygen evolution reaction (OER); however, the role of these PBA-derived catalysts in the OER is still ambiguous. Herein, by simply controlling synthesis temperature, a bimetallic PBA-derived O,N-codoped Ni-Fe carbide, can be well tuned to optimize structure and OER performance. Importantly, by a series of ex situ and in situ investigations, real active species of NiFeOx Hy are in situ formed on the surface during the OER, which reveals a "pre-catalyst" role of O,N-codoped Ni-Fe carbides. Furthermore, it has been successfully applied to highly efficient Zn-air batteries and outplays its RuO2 counterpart. When applied to photoelectrocatalytic water oxidation as the co-catalyst, it improves the performance of the BiVO4 photoanode by enhancing hole collecting and transporting ability. We believe this research not only provides a highly efficient and low-cost electrocatalyst for the OER, but also unveils the "pre-catalyst" role of PBA-derived materials in energy-storage and conversion devices.

Tunable Hollow Bimetallic MnFe Prussian Blue Analogue as the Targeted pH-Responsive Delivery System for Anticancer Drugs.

Owning to the improved ability of selectivity and penetration toward cancer cells, drug delivery systems (DDSs) play essential roles in chemotherapy for solid tumors. Herein, a series of bimetallic MnFe Prussian blue analogues (PBAs) with a tunable nanostructure was prepared by using sodium citrate (SC) as a structure regulator (represented by MnFe-PBA-SC). An advanced targeted drug delivery system was obtained by adding folic acid (FA) to the preparation system of MnFe-PBA-SC nanospheres (denoted as MnFe-PBA-SC-FA). The shape of pure MnFe PBA was changed from a typical nanocube to a hollow nanosphere when adding SC, leading to the formation of the core-shell nanospheres of the MnFe-PBA-SC-FA composite. The hollow nanostructures and intrinsic cavities in PBA can carry large amounts of doxorubicin (DOX), showing a high loading efficiency of MnFe-PBA-SC1.0-FA (91.8%), which was higher than that in MnFe-PBA-SC0.5 (63.2%). Additionally, the series of MnFe-PBAs showed pH-responsive drug release behaviors. A cell viability assay illustrated no remarkable cytotoxicity of MnFe-PBA-SC-FA against human breast cancer cells, Michigan Cancer Foundation-7 (MCF-7) cells, for 24 h. Confocal laser scanning showed that the MnFe-PBA-SC1.0-FA/DOX system significantly entered FA receptor-expressing MCF-7 cells in vitro and in vivo, while an increased DOX release was observed in the cytoplasm of the MCF-7 cells. In consequence, this novel anticancer delivery system based on bimetallic PBAs can be potentially applied to drug delivery.

Bimetallic Co2+ and Mn2+ Hexacyanoferrate for Hydrogen Peroxide Electrooxidation and Its Application in a Highly Sensitive Cholesterol Biosensor

AbstractIn this work, we report the synthesis and characterization of a bimetallic Prussian blue analogue containing Co and Mn as outer‐sphere metals (CoMnHCF). The material was a solid solution and its characterization revealed a chemical composition of Co2.05Mn0.95[Fe(CN)6]2 ⋅ 12H2O. The electrochemistry of this novel material showed the existence of two redox waves displaying quasi‐reversible kinetics, as expressed by the larger peak‐to‐peak separation upon increasing the potential sweep rate. Interestingly, the CoMnHCF solid exhibited high electrocatalytic activity for the oxidation of hydrogen peroxide, thus representing an appealing scaffold for the construction of biosensors. As a proof of concept, cholesterol oxidase was immobilized at the electrode surface by using a sol‐gel method, and the cyclic voltammograms were recorded at increasing concentrations of cholesterol. The biosensor showed a detection limit of 30 μM and two linear ranges with excellent sensitivity of 385 mA cm−2 M−1 between 50 and 150 μM, and an adequate sensitivity of 80 mA cm−2 M−1 between 150 and 1 mM. To the best of our knowledge, this is the first biosensor application of a pre‐synthesized bimetallic hexacyanometallate, thus exploiting its potential as an H2O2 electrooxidation catalyst.

Fe-CoP Electrocatalyst Derived from a Bimetallic Prussian Blue Analogue for Large-Current-Density Oxygen Evolution and Overall Water Splitting.

Industrial application of overall water splitting requires developing readily available, highly efficient, and stable oxygen evolution electrocatalysts that can efficiently drive large current density. This study reports a facile and practical method to fabricate a non‐noble metal catalyst by directly growing a Co‐Fe Prussian blue analogue on a 3D porous conductive substrate, which is further phosphorized into a bifunctional Fe‐doped CoP (Fe‐CoP) electrocatalyst. The Fe‐CoP/NF (nickel foam) catalyst shows efficient electrocatalytic activity for oxygen evolution reaction, requiring low overpotentials of 190, 295, and 428 mV to achieve 10, 500, and 1000 mA cm−2 current densities in 1.0 m KOH solution. In addition, the Fe‐CoP/NF can also function as a highly active electrocatalyst for hydrogen evolution reaction with a low overpotential of 78 mV at 10 mA cm−2 current density in alkaline solution. Thus, the Fe‐CoP/NF electrode with meso/macropores can act as both an anode and a cathode to fabricate an electrolyzer for overall water splitting, only requiring a cell voltage of 1.49 V to afford a 10 mA cm−2 current density with remarkable stability. This performance appears to be among the best reported values and is much better than that of the IrO2‐Pt/C‐based electrolyzer.

Magnetic and Mössbauer Studies on Mixed-Metal Cyano-Bridged Compounds Gu&lt;sub&gt;n&lt;/sub&gt;M&lt;sub&gt;1.5-n&lt;/sub&gt;[Fe(CN)&lt;sub&gt;6&lt;/sub&gt;]·xH&lt;sub&gt;2&lt;/sub&gt;O(M=Ni, Gu)

Mixed-metal cyano-bridged compounds GunM1.5-n[Fe (CN)6]·xH2O(M=Ni, Gu) have been prepared by co-precipitation. The magnetic results show that the compound Cu0.75Ni0.75[Fe (CN)6]·xH2O is ferromagnetic, undergoes a paramagnetic to the ferromagnetic transition temperature at 21.77 K. The paramagnetic curie temperature θ, residual magnetization Mr, and coercive field Hcare different from bimetallic Prussian Blue analogues Ni3[Fe (CN)6]2·xH2O and Cu3[Fe (CN)6]2· xH2O. As to Cu3[Fe (CN)6]2·xH2O, the magnetic susceptibilities follow the Curie-Weiss law and the Weiss paramagnetic Curie temperature is 19.1 K. The Mossbauer spectrum at room temperature reveals a doublet with the isomer shift parameter (-0.03 mm/s) and quadrupole splitting (QS= 1.09 mm/s). As the sample was cooled down to 16K, the magnetic splitting phenomenon was detected in the compound.