Prussian Blue Analogues Research Articles

Constructing low-cost stable zinc-ion batteries with sodium-rich monoclinic manganese hexacyanoferrate cathode

Manganese-based Prussian blue analogues are ideal candidate cathode materials for constructing high-voltage zinc-ion batteries. However, challenges have persisted in realizing envisioned highly stable electrochemical cycling systems due to manganese dissolution under aqueous conditions and self-corrosion of zinc metal anodes. Considering practical application demands and cost-effectiveness, non-aqueous organic zinc-ion batteries have shown significant development potential by avoiding interference from active hydrogen and offering a stable wide voltage window. Herein, a sodium-rich monoclinic structured manganese hexacyanoferrate (m-MnHCF) was synthesized via a simple coprecipitation method, achieving a stable high-voltage zinc-ion battery energy storage system in a diluted 0.2 M Zn(CF3SO3)2 electrolyte in acetonitrile, a non-protonic polar solvent. The battery exhibited a discharge specific capacity of 77 mAh g−1 at the current density of 1 A g−1 after 620 cycles. Furthermore, by circumventing interference from active hydrogen, a cost-advantaged zinc powder anode (Zn-P) was successfully introduced into the energy storage system. Assembled Zn-P||m-MnHCF cells exhibited stable cycling for 100 cycles at a current density of 0.5 A g−1 with close to 100 % coulombic efficiency, showcasing limitless possibilities for the future, as demonstrated by illuminated LED arrays.

Fe-Co PBA/rGO interface strategy enabling fast Al3+ intercalation for stable aqueous Al-ion batteries

Aqueous aluminum-ion batteries (AAIBs) have emerged as cost-effective and safe alternatives to lithium-ion batteries for storing energy. However, utilizing cathode materials like Prussian blue analogs (PBAs) to accommodate different metallic charge carriers faces challenges due to their low conductivity and slow redox kinetics. To overcome these issues, we propose a novel Fe-Co PBA/rGO nanocomposite with a strong interfacial chemical coupling between Fe-Co PBA and rGO. By combining theoretical calculations with experimental analysis, we have identified the essential role of interfacial interactions in regulating the electronic state and diffusion barriers of Al3+ within the Fe-Co PBA framework. Moreover, a three-dimensional structure that is tightly enclosed by ultrathin rGO sheets was successfully formed, ensuring excellent structural stability. Ex-situ XPS and XRD investigations have further clarified the electrochemical mechanism of the Fe-Co PBA/rGO cathode, revealing reversible redox reactions between Fe2+/Fe3+ and Co3+/Co2+ states during the insertion and extraction of Al3+. These inherent properties contribute to the remarkable cycling stability of the Fe-Co PBA/rGO cathode, achieving 66.7 mAh/g at 1 A/g after 1500 cycles, and high electrochemical reversibility. Additionally, we have successfully built a MoO3//Fe-Co PBA/rGO full battery with a capacity of 53.6 mAh/g over 2000 cycles at 1 A/g. This outcome further emphasizes its significant potential in electronic applications related to energy storage.

Mn-based Prussian blue analogues: Multifunctional nanozymes for hydrogen peroxide detection and photothermal therapy of tumors

Nanozymes have the advantages of simple synthesis, high stability, low cost and easy recycling, and can be applied in many fields including molecular detection, disease diagnosis and cancer therapy. However, most of the current nanozymes suffer from the defects of low catalytic activity and single function, which limits their sensing sensitivity and multifunctional applications. The development of highly active and multifunctional nanozymes is an important way to realize multidisciplinary applications. In this work, Mn-based Prussian blue analogues (Mn-PBA) and their derived double-shelled nanoboxes (DSNBs) are synthesized by co-precipitation method. The nanobox structure of DSNBs formed by etching Mn-PBA with tannic acid endows Mn-PBA DSNBs with better peroxidase-like activity than Mn-PBA. A colorimetric method for the rapid and sensitive determination of H2O2 is developed using Mn-PBA DSNBs-1.5 as a sensor with a detection limit as low as 0.62 μM. Moreover, Mn-PBA DSNBs-2 has excellent photothermal conversion ability, which can be applied to the photothermal therapy of tumors to inhibit the proliferation of tumor cells without damaging other tissues and organs. This study provides a new idea for the rational design of nanozymes and the expansion of their multi-functional applications in various fields.

Nickel-doped red mud-based Prussian blue analogues heterogeneous activation of H2O2 for ciprofloxacin degradation: waste control by waste.

Red mud (RM) is a typical bulk solid waste with Fe/Al/Si/Ca-rich characteristics that has been used to prepare various heterogeneous catalysts such as iron-based catalysts and supported catalysts. Prussian blue analogues (PBA) is a low-cost, environmentally friendly, and active site rich iron-based metal organic framework, but its catalytic properties are adversely affected by their easy aggregation. In this study, nickel-doped RM-based PBA (RM-Ni PBA) was synthesized by acid dissolution-coprecipitation method for the degradation of ciprofloxacin (CIP). The characterization showed that RM-Ni PBA was a material with excellent dispersibility, large specific surface area, and abundant active sites. The degradation results showed that the removal efficiency of CIP in the RM-Ni PBA/H2O2 system was 16.63, 1.78, and 1.81 times that of RM, RM-PB, and Ni PBA, respectively. It was found that 1O2 was the main reactive oxygen species (ROS) dominated the degradation process, and its formation was accompanied by the mutual conversion of Ni(II)/Fe(II) and Ni(III)/Fe(III). Notably, the degradation process maintained a satisfactory efficiency over a wide pH range (3-9) and exhibited strong anti-interference ability against impurities such as Cl-, SO42-, and NO3-. The components and contents of RM-Ni PBA remained relatively stable during the degradation process. In addition, the degradation intermediates of CIP were identified, and possible degradation pathways were proposed. This study is expected to provide theoretical basis and technical guidance for the application of RM-based heterogeneous catalyst in the treatment of antibiotic wastewater.

Efficient visible light-induced H2 production by g-C3N4/NiFe Prussian blue composites

Hydrogen (H2) produced via photocatalytic water splitting shows great potential as a renewable alternative to fossil fuels, as it uses clean and renewable resources (water and solar light). However, low efficiency remains a significant challenge for this technology. In this study, we synthesized novel graphitic carbon nitride (GCN)–Prussian blue analog (PBA) heterostructure composites using suitable PBAs for photocatalytic reactions, and explored their application in visible-light-induced H2 production. GCN-PBA heterostructure composites were synthesized using PBAs containing Ni, Co, and Fe, and their photocatalytic activities under visible light irradiation were compared. The visible-light absorption characteristics and H2 production efficiency of the GCN-PBA composites were characterized. The GCN-NiFe heterostructure composite showed excellent visible-light-induced H2 production efficiency, indicating effective charge separation and transfer characteristics that enhanced the photocatalytic activity of GCN. These findings contribute to the development of efficient photocatalytic materials for solar H2 production, thereby contributing to the advancement of renewable energy technologies.

Preparation high-performance cathode of vacancy-free Prussian blue analogues for sodium ion batteries by directional capture of free Mn-ion

To address the issue of poor cycling performance and capacity of Mn-based Prussian Blue analogues (PBAs) as sodium ion battery cathodes due to the solubility of Mn ions, this study utilizes the strong chelating property of EDTA2− with Mn ions to hydrothermally modify the sodium-rich monoclinic Na1.75Mn[Fe(CN)6]0.94·2.25H2O synthesized under high salt conditions, in order to enhance its capacity and stability. The modified Na1.93Mn[Fe(CN)6]•2·.38H2O exhibits a discharge capacity of 156.16 mAh/g at 10 mA g−1 (91.86 % of the theoretical capacity), it still retains the highest discharge capacity (70.23 mAh/g) after 500 cycles at 100 mA g−1. Based on experimental analysis, the improvement in the electrochemical performance of PBAs was attributed to three main factors: (1) enhanced Na content; (2) suppression of defects; and (3) improved crystal structure.

NiFeCo alloy nanoparticles composited with phosphorus-doped vacancies-abundant carbon substrates as electrocatalyst for oxygen evolution reaction

Transition metal alloy nanoparticles are cost-effective electrocatalysts for oxygen evolution reactions. Preparing alloy catalysts with flexible controllability, high activity, and long-term stability is a challenge. By adjusting the proportion of metal atoms and engineering vacancies through their composite with a carbon substrate, we can enhance electron transfer and modulate the adsorption capacity of reaction intermediates. Herein, we synthesized a hybrid catalyst using Prussian blue analogs (PBAs) as the precursor, doped with Fe and Ni atoms, and subjected them to a defective engineering and phosphatization process. As an efficient alkaline OER electrocatalyst, the formation of the alloy increases the number of active sites, while the defect-rich phosphorus-doped carbon substrate improves internal electron transfer and mass transfer channels. The synthesized NiFeCoPC-1.5 electrocatalyst exhibits excellent catalytic activity with an overpotential of 211 mV at 10 mA cm−2 and a Tafel slope of 59 mV dec−1, and demonstrates good stability up to 1000 CV cycles. This work will expand the application of alloy nanoparticles in oxygen evolution electrodes.

Local Structure and Dynamics in MPt(CN)6 Prussian Blue Analogues.

We use a combination of X-ray pair distribution function (PDF) measurements, lattice dynamical calculations, and ab initio density functional theory (DFT) calculations to study the local structure and dynamics in various MPt(CN)6 Prussian blue analogues. In order to link directly the local distortions captured by the PDF with the lattice dynamics of this family, we develop and apply a new "interaction-space" PDF refinement approach. This approach yields effective harmonic force constants, from which the (experiment-derived) low-energy phonon dispersion relations can be approximated. Calculation of the corresponding Grüneisen parameters allows us to identify the key modes responsible for negative thermal expansion (NTE) as arising from correlated tilts of coordination octahedra. We compare our results against the phonon dispersion relations determined using DFT calculations, which identify the same NTE mechanism.

Cerium oxide /Co-Co Prussian blue analogue composite catalyst for enhanced peroxymonosulfate activation for effective removal of tetracycline hydrochloride from water.

In this paper, a novel CeO2/Co3[Co(CN)6]2 (CeO2/PBACo-Co) composite was prepared with co-precipitation and utilized to activate peroxymonosulfate (PMS) to eliminate tetracycline hydrochloride (TCH). Catalyst screening showed that the composite with a CeO2:PBACo-Co mass ratio of 1:5 (namely, 0.2-CeO2/PBACo-Co) had the best performance. The degradation efficiency of TCH in 0.2-CeO2/PBACo-Co/Oxone system was investigated. The experimental results illustrated that 98% of 50 mg/L TCH and 48.5% of TOC were degraded by 50 mg/L 0.2-CeO2/PBACo-Co and 400 mg/L Oxone within 120 min at 25 °C and initial pH 5.3. Recycling studies showed that the elimination rate of TCH can still achieve 85.8% after five cycles, suggesting that 0.2-CeO2/PBACo-Co composite processes good reusability. Trapping experiments and EPR tests revealed that the reaction system produced multiple active species (1O2, O2•-, SO4•-, and •OH). We proposed the catalytic mechanism of 0.2-CeO2/PBACo-Co for PMS activation, which mainly involves the promoted Co3+/Co2+ cycle by Ce3+ donated electrons. These results indicate that CeO2/PBACo-Co composite is an effective catalyst for wastewater remediation.

Suppressing the Jahn–Teller effect in Mn-based Prussian blue analogues by linear (N[dbnd]O) anions

Manganese-based Prussian blue analogues (PBAs) have been touted as a promising cathode material for sodium-ion batteries (SIBs) due to their low cost, long cycle life and high energy density. However, manganese-based PBAs perform poorly during cycling due to the Jahn-Teller effect. In this study, highly stable manganese nitrosylpentacyanoferrate (Mn[Fe(CN)5NO]) particles were synthesized using a simple hydrothermal method. The presence of nitroso group breaks the symmetry of the crystals to some extent, which is favorable to reduce the Jahn-Teller effect. Through experiments and DFT calculations, we confirm that the presence of linear (NO) anions reduces the lattice volume fluctuations of the samples during charging and discharging, thus contributing to the mitigation of the Jahn-Teller effect. The electrochemical properties of Mn[Fe(CN)5NO] were significantly improved compared to manganese hexacyanoferrate (MnFe[CN]6). Mn[Fe(CN)5NO] exhibited excellent sodium storage performance with an initial discharge capacity as high as 144.5 mAh/g at 20 mA g-1and capacity retention as high as 82.1 % after 400 cycles at 100 mA g−1. This Mn[Fe(CN)5NO] sample provides a promising cathode for sodium-ion batteries in large-scale energy storage systems.

Cascaded Nanozyme Based pH-Responsive Oxygenation for Targeted Eradication of Resistant Helicobacter Pylori.

Nanozymes, as substitutes for natural enzymes, are constructed as cascade catalysis systems for biomedical applications due to their inherent catalytic properties, high stability, tunable physicochemical properties, and environmental responsiveness. Herein, a multifunctional nanozyme is reported to initiate cascade enzymatic reactions specific in acidic environments for resistant Helicobacter pylori (H. pylori) targeting eradication. The cobalt-coated Prussian blue analog based FPB-Co-Ch NPs displays oxidase-, superoxide dismutase-, peroxidase-, and catalase- mimicking activities that trigger • and H2O2 to supply O2, thereby killing H. pylori in the stomach. To this end, chitosan is modified on the surface to exert bacterial targeted adhesion and improve the biocompatibility of the composite. In the intestinal environment, the cascade enzymatic activities are significantly inhibited, ensuring the biosafety of the treatment. In vitro, sensitive and resistant strains of H. pylori are cultured and the antibacterial activity is evaluated. In vivo, murine infection models are developed and its success is confirmed by gastric mucosal reculturing, Gram staining, H&E staining, and Giemsa staining. Additionally, the antibacterial capacity, anti-inflammation, repair effects, and biosafety of FPB-Co-Ch NPs are comprehensively investigated. This strategy renders a drug-free approach that specifically targets and kills H. pylori, restoring the damaged gastric mucosa while relieving inflammation.

High-Entropy Prussian Blue Analogues Enable Lattice Respiration for Ultrastable Aqueous Aluminum-Ion Batteries.

Aqueous aluminum ion batteries (AAIBs) hold significant potential for grid-scale energy storage owing to their intrinsic safety, high theoretical capacity, and abundance of aluminum. However, the strong electrostatic interactions and delayed charge compensation between high-charge-density aluminum ions and the fixed lattice in conventional cathodes impede the development of high-performance AAIBs. To address this issue, this work introduces, for the first time, high-entropy Prussian blue analogs (HEPBAs) as cathodes in AAIBs with unique lattice tolerance and efficient multipath electron transfer. Benefiting from the intrinsic long-range disorder and robust lattice strain field, HEPBAs enable the manifestation of the lattice respiration effect and minimize lattice volume changes, thereby achieving one of the best long-term stabilities (91.2% capacity retention after 10000 cycles at 5.0 A g-1) in AAIBs. Additionally, the interaction between the diverse metal atoms generates a broadened d-band and reduced degeneracy compared with conventional Prussian blue and its analogs (PBAs), which enhances the electron transfer efficiency with one of the best rate performance (79.2 mAh g-1 at 5.0 A g-1) in AAIBs. Furthermore, exceptional element selectivity in HEPBAs with unique cocktail effect can facile tune electrochemical behavior. Overall, the newly developed HEPBAs with a high-entropy effect exhibit promising solutions for advancing AAIBs and multivalent-ion batteries.

Mn-HCF@Fe-HCF Core–Shell Architecture: Enhancing Structural Stability and Electrochemical Performance of Sodium-Ion Batteries

To overcome the structural failure of Manganese-based Prussian blue analogue (Mn-HCF) as a cathode material of sodium ion batteries caused by Mn ion dissolution induced by Jahn–Teller effect, we coated Mn-HCF with iron-based Prussian blue (Fe-HCF) to prepare the core–shell Mn-HCF@Fe-HCF cathode material for sodium ion batteries through co-precipitation method. The research results indicate that this structure effectively blocks the direct contact between Mn-HCF and electrolyte, thereby minimizing the dissolution of [Formula: see text] in the electrolyte and significantly improving the cycling stability and rate performance. The discharge capacity of this material at a current density of 0.1[Formula: see text]C (14[Formula: see text]mA[Formula: see text][Formula: see text] is 129.7[Formula: see text]mAh[Formula: see text][Formula: see text]. It still has a capacity of 87.4[Formula: see text]mAh[Formula: see text][Formula: see text] at a current density of 2[Formula: see text]C (280[Formula: see text]mA[Formula: see text][Formula: see text], and still has a capacity retention rate of 84.3% (91[Formula: see text]mAh[Formula: see text][Formula: see text] after 100 cycles at a current density of 0.5[Formula: see text]C (70[Formula: see text]mA[Formula: see text][Formula: see text]. Compared with the capacity retention rate of 51.5% of Mn-HCF 100 cycles before coating, the cycle stability of Mn-HCF@Fe-HCF is greatly improved.

Reconfiguring the Hydrogen Networks of Aqueous Electrolyte to Stabilize Iron Hexacyanoferrate for High-Voltage pH-Decoupled Cell.

Prussian blue analogs (PBAs) are promising insertion-type cathode materials for different types of aqueous batteries, capable of accommodating metal or non-metal ions. However, their practical application is hindered by their susceptibility to dissolution, which leads to a shortened lifespan. Herein, we have revealed that the dissolution of PBAs primarily originates from the locally elevated pH of electrolytes, which is caused by the proton co-insertion during discharge. To address this issue, the water-locking strategy has been implemented, which interrupts the generation and Grotthuss diffusion of protons by breaking the well-connected hydrogen bonding network in aqueous electrolytes. As a result, the hybrid electrolyte enables the iron hexacyanoferrate to endure over 1000 cycles at a 1 C rate and supports a high-voltage pH-decoupled cell with an average voltage of 1.95 V. These findings provide insights for mitigating the dissolution of electrode materials, thereby enhancing the viability and performance of aqueous batteries.

Reconfiguring the Hydrogen Networks of Aqueous Electrolyte to Stabilize Iron Hexacyanoferrate for High‐Voltage Decoupled Cell

Prussian blue analogs (PBAs) as insertion‐type cathodes have attracted significant attention in various aqueous batteries to accommodate metal or non‐metal ions while suffering from serious dissolution and consequent inferior lifespan. Herein, we reveal that the dissolution of PBAs primarily originates from the locally elevated pH of electrolytes that are caused by proton co‐insertion during discharge. To address this issue, a water‐locking electrolyte (WLE) has been strategically implemented, which interrupts the generation and Grotthuss diffusion of protons by breaking the well‐connected hydrogen bonding network in aqueous electrolytes. As a result, the WLE enables the iron hexacyanoferrate to endure over 1000 cycles at a 1C rate and supports a high‐voltage decoupled cell with an average voltage of 1.95 V. These findings provide insights for mitigating dissolution problems in electrode materials, thereby enhancing the viability and performance of aqueous batteries.

Periodic Stratification of Colloids in a Liquid Phase Produced by a Precipitation Reaction and Gel Swelling.

Pattern formation is a frequent phenomenon occurring in animate and inanimate systems. The interplay between the mass transport of the chemical species and the underlying chemical reaction networks generates most patterns in chemical systems. Periodic precipitation is an emblematic example of reaction-diffusion patterns, in which the process generates a spatial periodic structure in porous media. Here, we use the dormant reagent method to produce colloidal particles of Prussian blue (PB) and PB analogues at the liquid-gel interface. The generated particles produced a stable periodic stratification pattern in time in the liquid phase placed on top of the solid hydrogel. The phenomenon is governed by periodic swelling of the gel driven by the osmotic stress and stability of the formed particles. To illustrate the phenomenon, we developed an extended reaction-diffusion model, which incorporated the gel swelling and sedimentation effect of the formed colloids and could qualitatively reproduce the pattern formation in the liquid phase.

Continuous and Scalable Synthesis of Prussian Blue Analogues with Tunable Structure and Composition in Surfactant-Free Microreactor for Stable Zinc-Ion Storage.

We represent a segmented flow surfactant-free microfluidic strategy for continuous synthesis of Prussian blue analogues (PBAs) with high dispersity and high crystallization. Representative zinc hexacyanoferrate (ZnHCF) nanocubes were successfully synthesized in a microfluidic reactor within a few minutes via the cooperation method and possessed lower contents of crystal water and Fe(CN)6 3- vacancies than that of synthesis in bulk solution. The nucleation and particle growth process can be precisely controlled by the exploration of different flow rates and reaction temperatures during the formation of ZnHCF nanocubes in segmented flow microfluidic reactors. High crystallinity, low crystal water and vacancies in the ZnHCF structure were presented at relatively high temperatures for the crystal growth process. High-quality ZnHCF with a low content of crystal water showed excellent electrochemical activity and stability towards zinc-ion storage. The continuous and scalable synthesis approach can be extended to the fabrication of other PBAs such as NiHCF, CoHCF, MnHCF, and CuHCF with high dispersity without using any surfactants. The controllable construction of PBAs with tunable properties in microfluidic reactors provides a promising direction to minimize the gap between commercial reality and laboratory research.

Hollow Stair-Stepping Spherical High-Entropy Prussian Blue Analogue for High-Rate Sodium Ion Batteries.

Prussian blue analogues (PBAs) are considered to be one of the most suitable sodium storage materials, especially with the introduction of the high-entropy (HE) concept into their structure to further improve their various abilities. However, severe agglomeration of the HEPBA particles still limits the fast charging capabilities. Here, an HEPBA (Nax(FeMnCoNiCu)[Fe(CN)6]y□1-y·nH2O) with a hollow stair-stepping spherical structure has been prepared through the chemical etching process of the traditional cubic structure of HEPBA. Electrochemical characterization (sodium ion battery), kinetic analysis, and COMSOL Multiphysics simulations reveal that the nature of the high-entropy and the hollow stair-stepping spherical structure can greatly improve the diffusion behavior of Na+ ions. Moreover, the hollow structure effectively mitigates the volume change of HEPBA during SIBs operation, ultimately extending the lifespan. Consequently, the as-prepared HEPBA cathode exhibits excellent rate performance (126.5 and 76.4 mAh g-1 at 0.1 and 4.0 A g-1, respectively) and stable long-term capability (maintaining its 75.6% capacity after 1000 cycles) due to its unique structure. Furthermore, the waste of the etching process can easily be recycled to prepare more HEPBA product. This processing method holds great promise for designing nanostructures of advanced high-entropy Prussian blue analogues for sodium ion batteries.

Catalytic membranes assembled by Co–Fe Prussian blue analogues functionalized graphene oxide nanosheets for rapid removal of contaminants

The catalytic membrane, combining confinement effect with advanced oxidation processes, exhibits great potential as an efficient technology for removing contaminants and mitigating membrane fouling. Herein, the Prussian blue analogues (PBAs) functionalized graphene oxide (GO) membranes, referred as PGMs, was successfully fabricated. It exhibited a package-like confined structure where Co–Fe PBAs were encapsulated within interconnected GO nanosheets. The surface properties, internal structure as well as the catalytic performance of PGMs were controlled by adjusting the amount of Co–Fe PBAs anchored on GO nanosheets. The designed PGM as efficient peroxymonosulfate activator exhibited exceptional catalytic performance, achieving complete removal of bisphenol A (BPA) with a retention time of 31 ms. The corresponding first-order rate constant was 6000 min−1, which surpassed conventional batch system by four orders of magnitude (0.2194 min−1). Moreover, the redox cycle involving Fe2+ and Co3+, coupled with the effective suppression of ion leaching from Co–Fe PBAs nanoparticles (<10 μg/L) through GO protective layers, ensured the stable catalytic performance of PGM over 144 h. This study employs a novel approach to confine catalytic nanoparticles within two-dimensional nanosheets, demonstrating the potential applications of the resulting confined membrane in water treatment.

Prussian Blue Analogue Derived N-Doped Graphitic Carbon Wrapped Iron-Cobalt Nanoparticles as Recyclable Heterogeneous Catalysts for Friedel-Crafts Acylation

Prussian Blue Analogue Derived N-Doped Graphitic Carbon Wrapped Iron-Cobalt Nanoparticles as Recyclable Heterogeneous Catalysts for Friedel-Crafts Acylation