Prussian Blue Analogues Research Articles

Impact of Sodium on the Water Dynamics in Prussian Blue Analogues

Impact of Sodium on the Water Dynamics in Prussian Blue Analogues

Entropy and Electronic Structure Modulation of a Prussian Blue Analogue Cathode with Suppressed Phase Evolution for Potassium-Ion Batteries.

Severe structural evolution and high content of [Fe(CN)6]4- defects drastically deteriorate K-ion storage performances of Prussian blue-based cathodes. Herein, a potassium manganese iron copper hexacyanoferrate (KFe2/3Mn1/6Cu1/6HCF), with suppressed anionic vacancies, eliminated band gap, and low K-ion diffusion barrier, is regarded as a cathode for potassium-ion batteries. The entropy stabilization effect and robust Cu-N bond induced by the inert Cu-ion with large electronegativity boost KFe2/3Mn1/6Cu1/6HCF to exhibit great phase state stability, thus inhibiting the structural transition of monoclinic ↔ cubic. Hence, KFe2/3Mn1/6Cu1/6HCF undergoes a zero-stress solid-solution reaction mechanism, where Fe and Mn serve as dual active sites for charge compensation. Consequently, KFe2/3Mn1/6Cu1/6HCF displays a high reversible capacity of 127.5 mAh·g-1 with an energy density of 469.2 Wh·kg-1 at 10 mA·g-1 and superior cyclic stability with a high retention of 90.7% over 100 cycles. A high-energy-density K-ion full battery is assembled, contributing an ultralong lifetime over 1000 cycles with a low-capacity fading rate of 0.038% per cycle.

Dual Ion Co-Insertion Induced Spontaneous and Reversible Phase Conversion Chemistry for Unprecedented Zn2+ Storage.

Prussian blue analogues are highly promising electrode materials due to their versatile electrochemical activity and low cost. However, they often suffer from severe structural damage caused by the Jahn-Teller distortion and dissolution of high-spin outer metal ions, resulting in poor cycle life. Material modification and electrolyte regulation have been the common approaches to address this issue, albeit with very limited success. We report here a novel and efficient strategy to preserve structural stability by co-inserting Co2+ and Zn2+ ions in KCo[Fe(CN)6]. This co-insertion induced a spontaneous and reversible phase conversion by the replacement of low-spin inner ion (Fe3+), which efficiently relieves structural damage caused by Jahn-Teller distortion and metal-ion dissolution, leading to an outstanding Zn2+ storage capacity and an exceptional improvement of cycle life with a capacity retention of 97.7 % over 4400 cycles at 40 C. We also demonstrated the enhancement of co-intercalation on ion migration using a combined approach of experimental and density functional theory (DFT) calculations. This work provides an important progress to solve the cycle stability of Prussian blue analogues towards their practical application as electrode materials for aqueous batteries.

Dual Ion Co‐Insertion Induced Spontaneous and Reversible Phase Conversion Chemistry for Unprecedented Zn2+ Storage

AbstractPrussian blue analogues are highly promising electrode materials due to their versatile electrochemical activity and low cost. However, they often suffer from severe structural damage caused by the Jahn–Teller distortion and dissolution of high‐spin outer metal ions, resulting in poor cycle life. Material modification and electrolyte regulation have been the common approaches to address this issue, albeit with very limited success. We report here a novel and efficient strategy to preserve structural stability by co‐inserting Co2+ and Zn2+ ions in KCo[Fe(CN)6]. This co‐insertion induced a spontaneous and reversible phase conversion by the replacement of low‐spin inner ion (Fe3+), which efficiently relieves structural damage caused by Jahn–Teller distortion and metal‐ion dissolution, leading to an outstanding Zn2+ storage capacity and an exceptional improvement of cycle life with a capacity retention of 97.7 % over 4400 cycles at 40 C. We also demonstrated the enhancement of co‐intercalation on ion migration using a combined approach of experimental and density functional theory (DFT) calculations. This work provides an important progress to solve the cycle stability of Prussian blue analogues towards their practical application as electrode materials for aqueous batteries.

Oxygen Plasma Triggered Co−O−Fe Motif in Prussian Blue Analogue for Efficient and Robust Alkaline Water Oxidation

AbstractIn the context of oxygen evolution reaction (OER), the construction of high‐valence transition metal sites to trigger the lattice oxygen oxidation mechanism is considered crucial for overcoming the performance limitations of traditional adsorbate evolution mechanism. However, the dynamic evolution of lattice oxygen during the reaction poses significant challenges for the stability of high‐valence metal sites, particularly in high‐current‐density water‐splitting systems. Here, we have successfully constructed Co−O−Fe catalytic active motifs in cobalt‐iron Prussian blue analogs (CoFe‐PBA) through oxygen plasma bombardment, effectively activating lattice oxygen reactivity while sustaining robust stability. Our spectroscopic and theoretical studies reveal that the Co−O−Fe bridged motifs enable a unique double‐exchange interaction between Co and Fe atoms, promoting the formation of high‐valence Co species as OER active centers while maintaining Fe in a low‐valence state, preventing its dissolution. The resultant catalyst (CoFe‐PBA‐30) requires an overpotential of only 276 mV to achieve 1000 mA cm−2. Furthermore, the assembled alkaline exchange membrane electrolyzer using CoFe‐PBA‐30 as anode material achieves a high current density of 1 A cm−2 at 1.76 V and continuously operates for 250 hours with negligible degradation. This work provides significant insights for activating lattice oxygen redox without compromising structure stability in practical water electrolyzers.

Dual Redox Reactions of Silver Hexacyanoferrate Prussian Blue Analogue Enable Superior Electrochemical Performance for Zinc‐ion Storage**

AbstractPrussian blue analogues (PBAs) have been employed as host materials of aqueous zinc‐ion batteries (ZIBs), however, they suffer from low capacity and poor cycling stability due to limited electron transfer and the presence of interstitial water in PBAs. Herein, a vacancy and water‐free silver hexacyanoferrate K0.95Ag3.05Fe(CN)6 (AgHCF‐3) was synthesized by adjusting the ratio of K and Ag in the framework. It offers nearly four electrons involving two sequential redox reactions, namely, Fe3+/Fe2+ and Ag+/Ag0, to deliver a large capacity of 179.6 mAh g−1 at 20 mA g−1 with Coulomb efficiency of ~100 %. The Zn//AgHCF‐3 cell delivers an estimated energy density of 200 Wh kg−1, surpassing reported PBAs‐based ZIBs. The formation of Ag0 in the cycling process merits favorable rate performance of AgHCF‐3 (156.4 mAh g−1 at 200 mA g−1 with 80.3 % capacity retention after 100 cycles). This investigation paves new pathways for high‐capacity PBA cathodes.

Prussian Blue Analogue Framework Hosts for Li–S Batteries

Prussian Blue Analogue Framework Hosts for Li–S Batteries

Central metal coordination environment optimization enhances Na diffusion and structural stability in Prussian blue analogues

Prussian blue analogues, particularly metal hexacyanoferrates with double octahedral coordination (DOC) structures, hold great promise as cathode materials for sodium-ion batteries. However, their practical application is hindered by limited structural stability and restricted ionic diffusion channels inherent to the DOC structure. In this study, we have successfully integrated a mixed tetrahedral and octahedral coordination (TOC) structure with the DOC structure by a dual polymerization and high-entropy strategy, thereby optimizing the central metal coordination environment in hexacyanoferrate cathodes. It leverages the TOC structure's superiorities in structural stability and ionic diffusion, resulting in a hexacyanoferrate-based cathode that exhibits exceptional performance, with a capacity retention of 81.6% after 1000 cycles at 0.5 A g-1 and high rate capabilities of 96.7 and 89.1 mAh g-1 at 0.5 and 1 A g-1, respectively. These findings not only underscore the potential of the TOC design for prussian blue cathodes but also pave the way for the development of high-performance, durable sodium-ion battery systems.

Ambient Synthesis of Vanadium-Based Prussian Blue Analogues Nanocubes for High-Performance and Durable Aqueous Zinc-Ion Batteries with Eutectic Electrolytes.

Prussian blue analogues (PBAs) have been widely studied in aqueous zinc-ion batteries (AZIBs) due to the characteristics of large specific surface area, open aperture, and straightforward synthesis. In this work, vanadium-based PBA nanocubes were firstly prepared using a mild in situ conversion strategy at room temperature without the protection of noble gas. Benefiting from the multiple-redox active sites of V3+/V4+, V4+/V5+, and Fe2+/Fe3+, the cathode exhibited an excellent discharge specific capacity of 200 mAh g-1 in AZIBs, which is much higher than those of other metal-based PBAs nanocubes. To further improve the long-term cycling stability of the V-PBA cathode, a high concentration water-in-salt electrolyte (4.5 M ZnSO4+3 M Zn(OTf)2), and a water-based eutectic electrolyte (5.55 M glucose+3 M Zn(OTf)2) were designed to successfully inhibit the dissolution of vanadium and improve the deposition of Zn2+ onto the zinc anode. More importantly, the assembled AZIBs maintained 55 % of their highest discharge specific capacity even after 10000 cycles at 10 A g-1 with superior rate capability. This study provides a new strategy for the preparation of pure PBA nanostructures and a new direction for enhancing the long-term cycling stability of PBA-based AZIBs at high current densities for industrialization prospects.

High-Entropy Prussian Blue Analogue Derived Heterostructure Nanoparticles as Bifunctional Oxygen Conversion Electrocatalysts for the Rechargeable Zinc-Air Battery.

In response to energy challenges, rechargeable zinc-air batteries (RZABs) serve as an ideal platform for energy storage with a high energy density and safety. Nevertheless, addressing the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in RZAB requires highly active and robust electrocatalysts. High-entropy Prussian blue analogues (HEPBAs), formed by mixing diverse metals within a single lattice, exhibit enhanced stability due to their increased mixing entropy, which lowers the Gibbs free energy. HEPBAs innately enable sacrificial templating, an effective way to synthesize complex structures. Impressively, in this study, we successfully transform HEPBAs into exquisite multiphase (multimetallic alloy, metal carbide, and metal oxide) heterostructure nanoparticles through a controlled synthesis process. The elusive multiphase heterostructure nanoparticles manifested two active sites for selective ORR and OER. By integrating CNT into HEPBA-derived nanoparticles (HEPBA/CNT-800), the HEPBA/CNT-800 demonstrates superior activity toward both ORR (E1/2 = 0.77 V) in a 0.1 M KOH solution and the OER (η = 330 mV at 50 mA cm-2) in a 1 M KOH solution. The RZAB with a HEPBA/CNT-based air electrode demonstrated an open-circuit voltage of 1.39 V and provided a significant energy density of 71 mW cm-2. Moreover, the charge and discharge cycles lasting up to 40 h at a current density of 5 mA cm-2 demonstrate its excellent stability. This work provides an alternative avenue for the rational design of HEPBA's derivative for a sustainable rechargeable metal-air battery platform.

A Dual Effect Additive Modified Electrolyte Strategy to Improve the Electrochemical Performance of Zinc-Based Prussian Blue Analogs Energy Storage Device.

Prussian blue analogs (PBA) exhibit excellent potential for energy storage due to their unique three-dimensional open framework and abundant redox active sites. However, the dissolution of transition metal ions in water can compromise the structural integrity of PBAs, leading to significant issues such as low cycle life and capacity decay. To address these challenges, we proposed a dual-effect additive-modified electrolyte method to alleviate such issues, introducing sodium ferrocyanide (Na4Fe(CN)6) into aqueous alkaline electrolytes. It could not only capture Zn2+ dissolved on the surface of Na1.86Zn1.46[Fe(CN)6]0.87 (ZnHCF) electrode material during the cycling process but also conduct redox reactions on the electrode surface to provide additional capacitance. Through experiments and molecular simulation calculations, it showed that Na4Fe(CN)6 can restrict the movement of Zn dissolution into the electrolyte on the electrode surface. Based on this, an asymmetric supercapacitor based on ZnHCF//activated carbon was assembled with a modified electrolyte. The assembled supercapacitor displayed a specific capacitance of 1,329.65 mF cm-2, a power density of 2,900 mW cm-2, and an energy density of 388.28 mW h cm-2. This study provides a new idea for the design and construction of stable and efficient PBA energy storage materials by inhibiting the leaching of transition metals in PBA.

Six element high-entropy Prussian blue analogue cathode enabling high cycle stability for sodium-ion batteries

Prussian blue analogues (PBA) are promising cathode materials for sodium-ion batteries. However, the cycle life of PBA is limited due to its structure instability during cycling. Here, we successfully introduce six transition metals into N coordination site to increase the configurational entropy, significantly improving the structure stability and cycle life of PBA cathode materials. Electrochemical characterization methods are used to compare the behavior of hexa-, penta-, quadr-, and tri-metal PBA, exhibiting the characteristic of performance increasing with entropy. Time-resolved in situ X-ray diffraction confirms the “quasi-zero-strain” structure of H-PBA during desodiation/sodiation process. X-ray absorption spectroscopy and density functional theory calculations reveal that Mn, Fe, Co and Cu contribute the high capacity of H-PBA, while Ni and Zn stabilize the structure. The strategy will inspire new ideas in designing long life cathode materials with high capacity for sodium-ion batteries.

Co/Er2O3/C ternary nanocomposites derived from cobalt/erbium Prussian blue analogs for efficient microwave absorption

This study presents the synthesis of Er[Co(CN)6], a Prussian blue analog (ErCo-PBA) with varied morphology, fabricated by modulating the solvent ratio between C2H6O and H2O. This approach leverages the solubility characteristics of K3[Co(CN)6] and the consequential influence of C2H6O on the crystal growth. When the solvent ratios are 1:8, 8:1, and 1:1, the resulting ErCo-PBA precursors nanorods, irregular particles, and spindle-shaped particles, respectively. After annealing, these precursors in an Ar environment allowed the Co/Er2O3/C derivatives to retain the morphology of the precursor well. Electromagnetic parameters testing revealed that Co/Er2O3/C-1 exhibits superior electromagnetic wave-absorbing (EMWA) performance among the synthesized derivatives with an effective absorption bandwidth of 5.1 GHz at 1.85 mm and a minimum reflection loss of −56.7 dB at 2.9 mm. The incorporation of Er2O3 is an effective method for adjusting and optimizing the electromagnetic parameters of materials, thereby enhancing the EMWA performance of Co/Er2O3/C composite. This study highlights the potential of rare-earth oxide/Co/C composites, synthesized through direct annealing rare-earth metal–organic frameworks, as an absorber and are promising candidate to achieve high-efficiency electromagnetic wave absorption.

Multi-core–shell nanoboxes comprising polydopamine-derived C coated NiCo@C and FeCo@C nanohybrid for enhanced electrochemical quantification of nitrofurantoin

The development of a high-performance electrochemical sensing platform for monitoring nitrofurantoin (NFT) levels in various real samples plays an important role in the research community worldwide. To accomplish this objective, the crucial challenge is to construct sensing interfaces with outstanding electrocatalytic capabilities. In the present work, a highly efficient metal@carbon electrocatalyst with porous and multi-core–shell nanobox structure comprising polydopamine (PDA)-derived C coated NiCo@C and FeCo@C nanohybrid (named as NiCo@C/FeCo@C@C) was fabricated by simply pyrolyzing NiCo@FeCo Prussian blue analogues (PBA)@PDA. The carbonization of PDA into carbon shells protected the framework from collapsing during high-temperature pyrolysis process, thus enlarging the specific surface areas and porosity. The NiCo@C/FeCo@C@C composite attained an enhanced electrochemical capability, such as an outstanding electronic conductivity from the double carbon shell with porous structure, a large number of active sites and a high electrocatalytic activity from the metallic alloy nanoparticles, which exhibited a highly sensitive response to NFT. Under optimized experimental conditions, the established NiCo@C/FeCo@C@C electrochemical sensor displayed a wide linear range of 0.05–100 μM for NFT determination, coupled with a low detection limit of 14 nM. The practical feasibility of this sensor was also confirmed by the analysis of NFT in tablet and lake water samples with outstanding recovery rates. Moreover, the sustainability of the sensor was demonstrated through its prominent performance in high reproducibility, selectivity and long-term stability. This study thus introduces an innovative approach for the advance of highly efficient electrocatalysts in the area of electrochemical sensing.

Porous and defective NiCo2O4 spinel derived from bimetallic NiCo-based Prussian blue analogue for enhanced hydrogen production via the urea electro-oxidation reaction

The efficient hydrogen production via overall water splitting is seriously restrained by the slow kinetics of the oxygen evolution reaction (OER). The substantially low potential for the urea electro-oxidation reaction (UOR) can tackle this problem by replacing the OER at the electrolyzer anode. Herein, the NiCo2O4 spinel with rich oxygen vacancies (Ov) and embedded within mesoporous carbon network (Ov-NiCo2O4@mC) was derived from NiCo-based Prussian blue analogous (NiCo PBA) and exploited as the bifunctional electrocatalyst of the UOR and OER for boost the hydrogen production via the overall water splitting. Benefiting to the regular skeleton and abundant dual metal sites of NiCo PBA, the derived Ov-NiCo2O4@mC comprises abundant oxygen vacancies, lattice defects, and adjustable electron structure. These features afford Ov-NiCo2O4@mC the improved UOR ability, showing the potential of 1.33 V versus reversible hydrogen electrode (RHE) at the current density of 10 mA cm−2, along with a small Tafel slopes of 31 mV dec-1, remarkably lower than that of the OER (1.51 V versus RHE, Tafel slope = 85 mV dec-1). The UOR performance of Ov-NiCo2O4@mC substantially outperforms to most of the reported Co and/or Ni-based electrocatalysts. Impressively, the assembled two-electrode urea-assisted overall water splitting device shows the small voltage for the hydrogen production (1.43 V versus RHE) and good long-term stability. The present work can provide a new alternative for the efficient hydrogen production using the MOFs-derivatives.

Hyaluronic acid modified prussian blue analogs/TiO₂ janus nanostructures through efficient charge separation to enhance photocatalytic-driven dual gas for achieve multimodal treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by the abnormal proliferation of fibroblast-like synoviocytes and changes in the joint synovium, including elevated reactive oxygen species, decreased pH, and reduced oxygen content. In this study, we synthesized a novel nanocomposite material, namely HA-PBA-TiO2 Janus nanocomposite, by in situ etching in prussian blue analogs doped with Co and Ni, followed by the growth of TiO2 nano-flowers and encapsulation in hyaluronic acid. When these janus nanoparticles diffused to the inflammatory sites of RA, they exhibited outstanding photocatalytic water-splitting ability under 660 nm laser irradiation, generating H2 and O2. This capability helps ameliorate the hypoxic microenvironment at RA inflammatory sites by eliminating reactive oxygen species (ROS) and enhancing antioxidation and oxygenation. Furthermore, owing to the doping of Co and Ni, HA-PBA-TiO2 exhibits photothermal conversion capability, which significant damage to FLS upon exposure to 660 nm laser irradiation, thereby controlling their aberrant proliferation. Through a series of in vitro and in vivo experiments, we validated the significant therapeutic efficacy of HA-PBA-TiO2 in treating RA, highlighting its broad prospects for application.

Synergistic effect of Na enrichment and F modification on copper Prussian blue analogue nanoparticles for supercapacitors

Synergistic effect of Na enrichment and F modification on copper Prussian blue analogue nanoparticles for supercapacitors

NiS2/FeS2 binary nanoparticles confined in interconnected carbon framework with regulated pore structure enabled by citric acid for enhanced sodium storage properties

Recently, pyrite iron disulfide (FeS2) has emerged as a promising anode candidate for sodium-ion batteries (SIBs) due to its high theoretical capacity, affordability, non-toxicity and abundant resource in nature. However, the utilization of FeS2 still confronts the challenges of inferior rate capability and cycling instability for sodium storage, stemming from its low electronic conductivity and substantial volume changes during cycling. Herein, to address these obstacles, NiS2/FeS2 binary nanoparticles encapsulated within a network of interconnected N-doped porous carbon framework (NiS2/FeS2@NPC) are prepared by a successive solid-state ball milling, carbonization and sulfurization strategy with coordination complex of nickel iron Prussian blue analogue (NiFe-PBA) as precursor. The introduction of citric acid plays a critical role for the formation of interconnected carbon framework with regulated internal porous structure, thereby achieving heterostructured NiS2/FeS2@NPC with modulated specific surface area and pore volume. The rational design of interconnected N-doped porous carbon framework and heterogeneous structure guarantees rapid ion/electron transport kinetics, alleviated mechanical stress, and enhanced structural integrity. Benefitting from these advantages, the optimal NiS2/FeS2@NPC-1 electrode exhibits a high reversible capacity (545 mAh/g at 1 A/g), superior rate capability (267 mAh/g at 5 A/g) and ultrastable long-term cycling performance (98.5 % retention over 1000 cycles at 5 A/g). This study presents a novel and efficient design approach for creating durable and high-rate anode materials based on metal sulfides for SIBs.

Visible light-assisted S-doped red mud-based Fe-Co PBA derivatives activated PMS for efficient degradation of oxytetracycline from acidic to alkaline conditions: Degradation mechanism, degradation pathways and toxicity evaluation

Building an economically efficient, adaptable, and environmentally friendly advanced oxidation system is crucial for the treatment of antibiotic wastewater. In this study, we prepared a sulfur-doped red mud (RM) based Fe-Co Prussian blue analog derivative material (SRPD) using solid waste RM. Due to the doping of sulfur, SRPD possessed more abundant active sites (Co2+/Fe2+) and superior photocatalytic performance compared to other materials. Therefore, the SRPD/peroxymonosulfate (PMS)/Vis system exhibited the best degradation performance for oxytetracycline (OTC), with good reusability, resistance to impurity anions, adaptability to different water qualities, no secondary pollution, and maintained excellent performance under acidic, neutral, and alkaline conditions. Analysis has shown that the participation of surface S2- species in active sites regeneration was an important reason for achieving satisfactory degradation efficiency under neutral and alkaline conditions. In addition, there were significant differences in the charge transfer ability, surface morphology, and surface composition of SRPD in different pH systems, which affected the amount and types of main reactive oxygen species generated by PMS activation. As a result, the degradation pathways of OTC in SRPD/PMS/Vis systems with different pH values were somewhat different, but the detoxification ability towards OTC was excellent. This study exhibits certain reference significance for improving the degradation performance under neutral and alkaline conditions, and is an excellent candidate system for practical wastewater treatment.

Defect-Engineered Coordination Compound Nanoparticles Based on Prussian Blue Analogues for Surface-Enhanced Raman Spectroscopy.

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for label-free chemical analysis. The emergence of nonmetallic materials as SERS substrates, offering chemical signal enhancements, presents an exciting direction for achieving reproducible and biocompatible SERS, a challenge with traditional metallic substrates. Despite the potential, the realm of nonmetallic SERS substrates, particularly nanoparticles, remains largely untapped. Here, we present defect-engineered coordination compounds (DECCs) based on Prussian blue analogues (PBAs) as a class of nonmetallic nanoparticle-based SERS substrates. We demonstrate the utility and flexibility of the DECC template by incorporating various metal (M) elements into PBAs to synthesize nanoparticles that deliver substantial chemical mechanism (CM)-based enhancements to the Raman signal with a ∼ 108-fold increase. The introduction of the M-PBA-based DECC nanoparticles as a class of SERS substrates represents a pioneering stride, enabling the straightforward and systematic exploration of a library of compounds for SERS-based analysis of a wide range of target molecules, especially biomolecules.