Search Results (73)

Aqueous zinc-ion batteries (AZIBs) are regarded as promising electrochemical energy storage devices owing to their low cost, intrinsic safety, abundant zinc reserves, and desirable specific capacity. Prussian blue analogues (PBAs) have been extensively investigated because of their inexpensive raw materials, ease of fabrication, open frameworks, and high theoretical specific capacity; however, the application of PBAs as cathode materials for aqueous zinc-ion batteries (AZIBs) is hindered by poor cycling performance and limited capacity. In this work, a small amount of manganese ions was successfully introduced into the N-coordinated metal sites of zinc hexacyanoferrate (ZnHCF) to tailor its electrochemical stability. The N-coordinated metal species in PBAs directly influence the intercalation chemistry of Zn ions. The coexistence of manganese and zinc in manganese-substituted zinc hexacyanoferrates (MZHCFs) generates a synergistic effect that suppresses Jahn–Teller distortion and cathode material dissolution, endowing MZHCFs with superior cycling performance compared with PBAs containing a single N-coordinated metal (Mn or Zn). At a Mn content of 10%, a specific discharge capacity of 100 mAh g⁻¹ is achieved at a current density of 1 A g⁻¹, and the capacity retention is optimized, showing no decay relative to the initial discharge capacity after 2000 galvanostatic cycles. This study demonstrates that substituting the N-coordinated metal in PBAs with other metal ions is an effective strategy to improve their electrochemical cycling stability and capacity. Full article

This work presents a novel one-step plasma–solution synthesis of Prussian Blue (PB) and copper hexacyanoferrate (Cu-PBA) nanoparticles via underwater pulsed DC discharge. For the first time, the direct plasma-assisted formation of these coordination polymers is reported. The obtained materials were examined by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy (SEM). These analyses confirmed that the desired phases had formed, along with small amounts of oxide byproducts (α-Fe₂O₃, CuO) arising from the erosion of the electrodes. Photocatalytic activity was evaluated through the degradation of organic dyes (Reactive Red 6C, Rhodamine B, and Methylene Blue) under UV-light irradiation. Both catalysts achieved complete dye degradation within 90 min of UV irradiation (after an initial 30 min dark adsorption step, total experiment time 120 min). Notably, selective performance was observed: PB exhibited higher activity toward the cationic dye Methylene Blue, while Cu-PBA was more effective for the anionic dye Reactive Red 6C. This selectivity is attributed to the specific oxide impurities forming heterojunctions that facilitate charge separation and generate distinct reactive oxygen species. The plasma–liquid method offers a rapid and environmentally benign route to functional PBA-based composites, with potentially scalable characteristics pending further engineering optimization. These findings highlight the potential of utilizing synthesis-induced impurities to tailor photocatalytic selectivity for water purification applications. Full article

As a promising class of catalysts for enzymatic glucose sensors, Prussian blue analogues (PBAs) exhibit exceptional biomimetic activity. However, their performance is often constrained by poor intrinsic conductivity, which typically limits their sensitivity. To address this limitation, this study presents an effective approach using direct in situ growth of PBAs on the electrode substrates, which enables the effective integration of PBA-based electrochemical systems. A porous Ni framework was first electrodeposited onto a screen-printed gold electrode substrate, followed by the reduction of Pt onto the porous Ni. Subsequently, NiFe PBA was synthesized in situ using the porous Pt/Ni structure as a sacrificial template. Functionalized with glucose oxidase (GO_x), the PBA/Pt/Ni biosensor exhibited excellent performance for glucose detection in buffer solution, with a high sensitivity of 262.6 μA mM⁻¹·cm⁻² and an ultra-low detection limit of 1.45 μM (calculated at a signal-to-noise ratio of 3, S/N = 3). Notably, its sensitivity corresponds to a two-fold enhancement relative to the electrodes modified with commercial Prussian blue using the conventional drop-casting method. Even when tested in human sweat samples, the biosensor achieved a high sensitivity of 236.4 μA mM⁻¹·cm⁻² and a linear detection range of 20–1000 μM, with the broad sensing range fully encompassing the typical physiological concentrations of glucose in human sweat. This excellent performance arises from the high specific surface area of the porous Pt/Ni structure and the tight connection between PBA and the sacrificial Ni anode. This research presents a promising design strategy for advanced, wearable, and non-invasive health-monitoring platforms. Full article

Solid-contact ion-selective electrodes (SC-ISEs) are typically constructed using ion-selective membrane (ISM)-based configurations. However, such structures often suffer from water-layer formation and the weak mechanical stability of the ISM. Herein, we report an ISM-free K⁺-SC-ISE based on a Prussian blue analogue transducer, KMnFe(CN)₆, eliminating the need for a conventional ionophore-based ISM layer. KMnFe(CN)₆ was synthesized via a one-step citrate-assisted co-precipitation method. The material functions as a bifunctional transducer, in which the open framework structure with ion-transport channels enables selective K⁺ recognition, while the redox-active Mn centers facilitate ion-to-electron transduction. The fabricated KMnFe(CN)₆-based K⁺ sensor exhibits a near-Nernstian response with a sensitivity of 52.3 ± 1.0 mV dec⁻¹ and a rapid response time of 25 s. The linear range and limit of detection were determined to 10⁻⁴ to 10⁻¹ M and 5.8 × 10⁻⁵ M, respectively. The sensor also demonstrates selectivity to representative interfering ions, with log K_ij of −2.39 ± 0.12 (Na⁺), −2.86 ± 0.09 (Li⁺), −3.06 ± 0.09 (Ca²⁺), −2.74 ± 0.12 (Mg²⁺) and −0.95 ± 0.08 (NH₄⁺). By eliminating the ISM layer, the water-layer effect is effectively avoided, resulting in excellent long-term stability with a potential drift of 57.2 ± 6.1 μV h⁻¹ over 7 days. The sensor was further applied to the analysis of K⁺ in real lake water samples, where the measured concentration showed good agreement with ion chromatography results. This work provides an ISM-free SC-ISE strategy for ion analysis in water environments. Full article

Sodium-ion batteries (SIBs) have emerged as one of the most promising alternatives to lithium-ion systems, driven by the abundance and low cost of sodium resources as well as the urgent demand for sustainable large-scale energy storage. In recent years, remarkable advances have been achieved in electrode materials, electrolytes, and interfacial engineering, which have significantly improved the electrochemical performance of SIBs. Hard carbons and alloy-type anodes have shown encouraging progress in balancing capacity and stability, while layered oxides, polyanionic compounds, and Prussian blue analogues are leading candidates for cathodes due to their structural diversity and tunable redox properties. Concurrently, the development of advanced liquid and solid electrolytes, together with strategies to control the solid–electrolyte interphase (SEI) and cathode–electrolyte interphase (CEI), is enhancing safety and long-term cycling. Despite these achievements, critical challenges remain, including limited energy density, volumetric expansion in alloying anodes, interfacial instability, and scalability issues. This review provides a comprehensive overview of the fundamental principles, recent material innovations, and failure mechanisms of SIBs, and highlights the current status of industrial progress led by companies such as Faradion, HiNa Battery, CATL, and Tiamat. Finally, future perspectives are discussed, emphasizing the role of sodium-ion technology in grid-scale storage, renewable energy integration, and sustainable battery recycling. By bridging academic advances and industrial development, this article outlines the roadmap toward the commercialization of sodium-ion batteries. Full article

Sodium-ion batteries (SIBs) are regarded as an important complementary technology to lithium-ion batteries due to their abundant resources and low cost, demonstrating broad application prospects, especially in large-scale energy storage. As a core component of SIBs, the cathode material directly determines key performance indicators such as energy density, cycling stability, and rate capability. Currently, the main cathode material systems under extensive research include transition metal oxides, polyanionic compounds, and Prussian blue analogues (PBAs), each exhibiting distinct characteristics in terms of crystal structure and electrochemical performance. Transition metal oxides have attracted significant research interest owing to their high specific capacity, while polyanionic compounds are known for their excellent structural stability and operating voltage. PBAs, on the other hand, have gained considerable attention due to their open framework structure and simple synthesis process. In recent years, modification strategies such as nanostructure engineering, surface coating, and elemental doping have significantly enhanced the electrochemical performance of these cathode materials. Future research should focus on addressing critical scientific challenges, including low intrinsic electronic conductivity and poor interfacial stability, while also exploring novel composite cathode material systems to facilitate the practical application of sodium-ion batteries. Full article

Seawater electrolysis offers a promising route for sustainable hydrogen production in coastal areas, leveraging solar energy while reducing freshwater consumption. Yet, chloride-induced corrosion severely limits conventional electrodes such as titanium, which depend on passive titanium dioxide films and display minimal hydrogen evolution reaction activity (|i₀,H₂| ≈ 0.001–0.01 A/m²). Here, we report for the first time the use of copper-based coordination compounds—a triazole-derived polymer (CC_Cu) and a Prussian Blue Analogue (CuHCF)—as dual-function electrodes combining corrosion resistance with electrocatalytic activity. Structural integrity was verified by FTIR, TGA, XRD, and SEM/EDS analyses. Electrochemical tests in 0.5 M NaCl, interpreted using mixed potential theory, revealed corrosion potentials (E_corr) of −40 mV versus Standard Hydrogen Electrode (CuHCF) and −23 mV versus Standard Hydrogen Electrode (CC_Cu), and corrosion current densities of 0.259 and 0.379 A/m², respectively. Both exhibited hydrogen evolution reaction exchange current densities significantly higher than titanium (0.019 A/m² for CuHCF and 0.062 A/m² for CC_Cu). CuHCF achieved a Tafel slope of 222 mV/dec, comparable to NiMoP alloys and carbon steel. Complementary density functional theory calculations elucidated how metal–ligand interactions and electronic redistribution govern both catalytic performance and degradation. These findings introduce a new concept of semi-electrocatalysts, where copper coordination compounds act as structurally adaptive, low-cost materials bridging corrosion resistance and hydrogen evolution in seawater systems. Full article

Redox mediators are central to electrochemical biosensors, enabling electron transfer between deeply buried enzymatic cofactors and electrode surfaces when direct electron transfer is kinetically inaccessible. Among all design parameters, the reversibility of mediator redox cycling remains the most decisive yet under-examined factor governing biosensor stability, drift and long-term reproducibility. This review establishes reversibility as a unifying framework grounded in inorganic and organometallic redox chemistry, with particular emphasis on coordination environments, ligand-field effects and outer-sphere electron-transfer pathways. Recent advances (2010–2025) in ruthenium and osmium polypyridyl complexes, cobalt macrocycles, hexacyanoferrates and Prussian Blue analogues are examined alongside ferrocene derivatives and other organometallic mediators, which together define the upper limits of reversible behaviour. Organic mediator families, including quinones, phenazines, indophenols, aminophenols and viologens, are discussed as mechanistic contrasts that highlight the structural and thermodynamic constraints that limit long-term cycling in aqueous media. Mechanistic indicators of reversibility, including peak separation, current ratios and heterogeneous electron-transfer rate constants, are linked to mediator architecture, coordination chemistry and immobilisation environment. By integrating molecular electrochemistry with applied sensor engineering, this review provides a mechanistically grounded basis for selecting or designing redox mediators that sustain efficient electron transfer, minimal fouling and calibration stability across diverse sensing platforms. Full article

Cobalt-based Prussian blue hollow spheres (CoHCF HSs) with different Co contents were synthesized using a self-templated coprecipitation technology. The microstructure and electrochemical properties of CoHCF HSs were investigated. The results indicate that all samples exhibit a face-centered cubic crystal structure. With increasing cobalt content in the Prussian blue analogues, the X-ray diffraction peaks shift toward higher angles due to the reduction in interplanar spacing. Computer simulations revealed that Na⁺ ions exhibit higher adsorption energies (ΔE_a) at Co sites (ΔE_a = 1.45 eV) compared to Fe sites (ΔE_a = 1.18 eV), which enables Co sites to adsorb more Na⁺ ions, providing greater sodium storage capacity. With increasing cobalt content, the reduced aspect ratio of CoHCF HSs surface nanoscale protrusions decreases the specific surface area. Consequently, the overall average CoHCF HSs size decreases with increasing cobalt content, which predominates the increase in specific surface area, contributing to supplying more active sites. The best electrochemical properties showed an initial capacity of 121.16 mAh g⁻¹ at a current density of 0.2 A g⁻¹ but not at the largest specific surface area. These findings suggest that improving the electrochemical performance of CoHCF electrodes requires consideration of the synergistic effects between specific surface area and elemental composition. Full article

The oxygen evolution reaction (OER) is a kinetic bottleneck in electrochemical water splitting, creating an urgent need for the development of efficient electrocatalysts. Prussian blue analogues (PBAs), a significant class of inorganic coordination polymers, have emerged as excellent precursors and pre-catalysts for preparing various OER nanocatalysts, owing to their numerous advantages such as tunable composition, controllable morphology, and structural derivability. This review systematically summarizes recent advances in PBA-based OER electrocatalysts, beginning with two core strategies: enhancing active site accessibility and utilization, and improving the intrinsic activity of each active site. We provide an in-depth discussion of the design principles for enhancing active site accessibility and utilization through constructing porous architectures, creating hierarchical porosity, and improving electrical conductivity. The review also details key approaches for improving intrinsic activity, including regulating electronic structure via elemental doping and optimizing active sites via defect engineering, while examining the underlying mechanisms for performance enhancement. Finally, current challenges and future research directions are outlined, offering a perspective on the potential applications of PBA-based catalysts in sustainable energy conversion systems. Full article

The high cost of hydrogen production is the primary factor limiting the development of the hydrogen energy industry chain. Additionally, due to the inefficiency of hydrogen production by water electrolysis technology, the development of high-performance catalysts is an effective means of producing low-cost hydrogen. In water electrolysis technology, the electrocatalytic activity of the electrode affects the kinetics of the oxygen evolution reaction (OER) and the hydrogen evolution rate. This study utilizes the liquid phase co-precipitation method to synthesize three types of Prussian blue analog (PBA) electrocatalytic materials: Fe/PBA(Fe₄[Fe(CN)₆]₃), Fe-Mn/PBA((Fe, Mn)₃[Fe(CN)₆]₂·nH₂O), and Fe-Mn-Co/PBA((Mn, Co, Fe)₃^II[Fe^III(CN)₆]₂·nH₂O). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses show that Fe-Mn-Co/PBA has a smaller particle size and higher crystallinity, and its grain boundary defects provide more active sites for electrochemical reactions. The electrochemical test shows that Fe-Mn-Co/PBA exhibits the best electrochemical performance. The overpotential of the oxygen evolution reaction (OER) under 1 M alkaline electrolyte at 10/50 mA·cm⁻² is 270/350 mV, with a Tafel slope of 48 mV·dec⁻¹, and stable electrocatalytic activity is maintained at 5 mA·cm⁻². All of these are attributed to the synergistic effect of Fe, Mn, and Co metal ions, grain refinement, and the generation of grain boundary defects and internal stresses. Full article

Prussian blue analogs (PBAs) are widely recognized as promising candidates for aqueous zinc-ion batteries (AZIBs) due to their stable three-dimensional framework structure. However, their further development is limited by their low specific capacity and unsatisfactory cycling performance, primarily caused by phase transformation during charge–discharge cycles. Herein, we employed a high-entropy strategy to introduce five different metal elements (Fe, Co, Ni, Mn, and Cu) into the nitrogen–coordinated M_a sites of PBAs, forming a high-entropy Prussian blue analog (HEPBA). By leveraging the cocktail effect of the high-entropy strategy, the phase transformation in the HEPBA was significantly suppressed. Consequently, the HEPBA as an AZIB cathode delivered a high reversible specific capacity of 132.1 mAh g⁻¹ at 0.1 A g⁻¹, and showed exceptional cycling stability with 84.7% capacity retention after 600 cycles at 0.5 A g⁻¹. This work provides innovative insights into the rational design of advanced cathode materials for AZIBs. Full article

Overuse of tert-butylhydroquinone (TBHQ) as a food antioxidant has the potential to pollute the environment and threaten human health. Therefore, it is imperative to develop precise and rapid methods to detect TBHQ in food products. In this study, Fe- and Mn-doped Prussian blue analogs (FeMn-PBAs) were prepared by co-precipitation, FeMn-PBAs/PAN was prepared by electrostatic spinning, and a novel FeMn@C/CNFs composite was prepared by carbonization in nitrogen. Bimetallic FeMn doping has been shown to reduce vacancy defects and enhance the structural stability of PBA. Furthermore, electrostatic spinning has been demonstrated to reduce the agglomeration of PBA nanoparticles, which are electrode-modifying materials with high stability and good electrical conductivity. The morphological and structural characteristics of the FeMn@C/CNF composites were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrochemical behavior of tert-butyl hydroquinone in FeMn@C/CNFs was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronocoulometry (CC). The results demonstrate that the sensor exhibits excellent repeatability, reproducibility, and anti-interference capabilities. The prepared electrochemical sensor can be effectively utilized for the detection of TBHQ in food samples such as soybean and peanut oil samples, proving its strong potential for practical applications. Full article

Polarized Small-Angle Neutron Scattering is a versatile low-energy neutron scattering technique that allows for the access of magnetic information on nanosize objects of size 2–100 nm, from individual properties like the magnetization distribution inside the object to the collective behaviors, e.g., spin-glass effects or long-range magnetic ordering. The multi-scale possibilities of this technique is particularly relevant to encompass simultaneously the individual and collective many-body phenomena. In this article, we report the direct measurement of the magnetic form factor of “Prussian Blue Analog” molecular-based Ferromagnetic nanoparticles ${\mathrm{Cs}}_{\mathrm{x}}^{\mathrm{I}}{\mathrm{Ni}}^{\mathrm{II}}\left[{\mathrm{Cr}}^{\mathrm{III}}{\left(\mathrm{CN}\right)}_6\right]$ embedded in a polymer matrix with use of Polarized Small-Angle Neutron Scattering. We show that PSANS is particularly adapted to evaluate the internal magnetization distribution in nanoparticles and determine their magnetic morphology. Full article