CoFe Prussian Blue Analogue Research Articles

Preparation of hollow CoFe Prussian blue analogues and their derived CoP-FeP nanoboxes as efficient electrocatalysts as oxygen evolution reactions

Reasonably designing and constructing transition metal based compounds with controllable composition and structure is a promising option for obtaining economically efficient oxygen evolution reaction (OER) electrocatalysts. This paper presents a one-pot self-templated epitaxial growth, phase transition and self-dissolution strategy for constructing hollow nanoboxes/solid nanocubes of CoFe bimetallic Prussian blue analogues (PBAs). The CoFe mixed phosphide with a porous hollow nanoboxes structure obtained after subsequent phosphating heat treatment exhibite enhanced OER electrocatalytic activity in alkaline media, exhibiting a low overpotential of 230 mV and a Tafel slope of 35.5 dec−1 at 10 mA cm−2, as well as excellent stability for 48 h. The excellent OER activity of CoP-FeP nanoboxes (CoP-FeP NBs) can be attributed to the combination effect between their composition and structure. Structurally, the exquisite porous hollow nanoboxes structure greatly expands the surface area, reduces ion diffusion pathways, and reduces charge transfer resistance. Compositionally, the inner transition metal phosphide exhibits good conductivity and undergoes surface reconstruction during OER, forming high valence Co(Fe)OOH active substances in situ. The strong interface coupling effect of CoOOH/FeOOH optimizes the electronic structure. This work presents a facile and efficient strategy for the construction of PBAs hollow structural materials and the exploitation of low-cost and efficient electrocatalysts.

Cyanide Linkage Isomerization Induced by Cobalt Oxidation-State Changes at a Co-Fe Prussian-Blue Analogue/ZnO Interface.

Understanding the interfacial composition in heterostructures is crucial for tailoring heterogenous electrochemical and photoelectrochemical processes. This work aims to elucidate the structure of a series of Co-Fe Prussian blue analogue modified ZnO (PBA/ZnO) electrodes with interface-sensitive vibrational sum frequency generation (VSFG) spectroscopy. Our measurements revealed, for the first time, a cyanide linkage isomerism at the PBA/ZnO interface, when the composite is fabricated at elevated temperatures. In situ VSFG spectro-electrochemistry measurements correlate the CoII➝CoIII oxidation with the flip of the bridging CN ligand from Co-NC-Fe coordination mode to a Co-CN-Fe one. Photoluminescence measurements and X-ray photoelectron spectroscopy reveal that this unprecedented linkage isomerism originates from surface defects, which act as oxidation sites for the PBA. The presence of such surface defects is correlated with the fabrication temperature for PBA/ZnO. Thus, this contribution identifies the interplay between the surface states of the ZnO substrates and the chemical composition of PBA at the ZnO surface, suggesting an easily accessible approach to control the chemical composition of the interface.

Dual defense against membrane fouling for efficient and sustainable oil/water separation on a novel super-hydrophilic/underwater superoleophobic and catalytic nanofibrous membrane

Membrane separation technology is widely recognized as an efficient method for treating organically polluted wastewater in virtue of high performance and straightforward operation. However, the practical application of membranes is inevitably confronted with contamination issues, presenting a major challenge in terms of fouling resistance. To address this issue, a defensive-offensive dual-defense strategy based on wettability and catalytic ability control is proposed. With this concept, a novel nanofibrous membrane with a unique structure was successfully prepared through polyacrylonitrile (PAN) electrospinning, pre-oxidation, CoFe Prussian blue analogue (PBA) and polypyrrole (PPy) modification, and calcination processes. For the passive defense mode, the as-prepared membrane has shown good underwater-superoleophobicity for various types of oils, good separation capability for corresponding oil–water emulsions with retention ratios of above 99 % and fluxes ranging from 231.5 to 1524.2 L·m−2·h−1·bar−1, as well as organic solvent (dimethylformamide, DMF) resistance. For the offensive defense mode, this membrane exhibits well catalytic degradation performance for refractory pollutants with the assistance of peroxymonosulfate (PMS), which is due to the membrane being decorated with catalytic nanoparticles that contain abundant encapsulated ultra-small Fe doped Co3O4 (∼2.28 nm), and that is much smaller than the size of the pristine PBA (∼33.8 nm). Notably, the surfactants present in oil-in-water emulsions are found to be the main cause of membrane fouling, where the cationic surfactants exhibit the most significant fouling effect, while the introduction of photo-Fenton-like catalysis can endow the membrane with excellent antifouling performance and extended service life, and nearly a fully recover of emulsion separation performance was achieved. Overall, this work paves pathways to the design of advanced membranes for sustainable wastewater treatment.

Prussian blue analogue derived porous hollow nanocages comprising polydopamine-derived N-doped C coated CoSe2/FeSe2 nanoparticles composited with N-doped graphitic C as an anode for high-rate Na-ion batteries

CoFe-Prussian blue analogue (CoFe-PBA) templated N-doped graphitic carbon (NGC) and polydopamine-derived carbon (PDA-20) double-coated CoSe2/FeSe2 nanoparticles are introduced as anodes for highly efficient sodium-ion batteries (SIBs). These nanoparticles are encapsulated within porous hollow nanocages, which exhibit remarkable stability in cyclic performance. The synthesis method involved co-precipitation, followed by PDA coating at varying concentrations and a subsequent selenization process. This resulted in the creation of (Co,Fe)Se-NGC nanocages, (Co,Fe)Se-NGC@PDA-20 hollow nanocages, and (Co,Fe)Se-NGC@PDA-100 filled nanocages. This strategic preparation approach leverages the synergistic effects of dual carbon coating, resulting in highly conductive and porous nanostructures. These structures facilitate rapid charge species diffusion, efficient electrolyte infiltration, and effective management of volumetric changes. When used as anodes for SIBs, the (Co,Fe)Se-NGC@PDA-20 hollow nanocages demonstrate impressive structural robustness and high-rate performance. They exhibit remarkable structural integrity, maintaining stable cycling performance for up to 200 cycles at 0.5 and 1.0 A g−1. In terms of rate capability, the hollow nanocages exhibit a high discharge capacity of 126 mA h g−1 at 10 A g−1. This clearly highlights the structural advantages of the prepared hollow nanocages.

Enhancing Oxygen Evolution Reaction through In Situ Electrochemical Oxidation for the Structural Control of Co-Fe Prussian Blue Analogue

The development of exceptionally efficient catalysts for the oxygen evolution reaction (OER) and gaining a deep understanding of their activity is essential for advancing electrochemical conversion technologies. Prussian blue analogues (PBAs) serve as promising pre-catalysts for the OER. However, PBAs, typically prepared through the conventional co-precipitation method, exhibit a lower active site density and limited electrical transport, making them suitable precursors for the derivation of PBA derivatives. In this research, we identified a significant enhancement in the electrocatalytic performance of Co-Fe Prussian blue analogue (CoFe PBA) through electrochemical oxidation. The cubic CoFe PBA was synthesized by one-step co-precipitation method using adjusting the amount of sodium citrate and potassium ferricyanide. After the electrochemical treatment, CoFe PBA demonstrates remarkable attributes, including a low overpotential of 331mV at a current density of 10mA·cm-2, a small Tafel slope of 50.4mV·dec-1, and excellent long-term stability during electrolysis in a 1M KOH alkaline medium for over 37h. Moreover, the electrochemical oxidation of CoFe PBA was comprehensive, employing techniques such as Transmission electron microscope, Powder X-ray diffraction, and X-ray photoelectron spectroscopy. These analyses confirmed the presence of real active substances, including CoOOH and a part of FeOOH species, further supporting the observed improvements in electrocatalytic activity.

Preparation of a three-dimensional bimetallic CoFex/ N-doped carbon nanomaterial used as modified electrode for the efficient electrochemical detection of l-tyrosine

The rapid and sensitive detection of l-tyrosine (L-Tyr) has become a vital issue in the fields of medicine and clinical analysis as lack or overdose of L-Tyr in human body could cause disease. In this paper, a three-dimensional cubic CoFex/N-doped carbon nanocomposite (CoFex-N,C) material was prepared by high-temperature calcination of CoFe-Prussian blue analogues (CoFe-PBA) in N2 atmosphere and then modified on glass carbon electrode (GCE) for L-Tyr detection. The prepared CoFex/N,C nanocomposite not only inherits the uniform morphology, and unique bimetallic active center of CoFe-PBA, but also possesses the high conductivity and large ratio area of nitrogen-doped carbon nanomaterials. Under optimum conditions, the CoFex/N,C nanocomposite electrode presented a broad linear scope of 0.8–354.84 μM, a low detection limit of 0.06 μM (S/N = 3), good anti-interference ability, and very high stability. In addition, the acceptable recoveries were obtained for real sample analysis.

Detection of a Jahn–Teller mode as an ultrafast fingerprint of spin-transition-induced charge transfer in CoFe Prussian Blue Analogue

Using sub-20-fs ultrafast spectroscopy, we unravel high-frequency vibrational coherences during the photoinduced charge transfer in the CoFe Prussian Blue Analogue, attributed to the transient activation of a low-symmetry Jahn–Teller mode.

Gold brocade coated CoFe PBA with enhanced peroxidase-like activity for a chemiluminescent imaging immunoassay.

Traditional chemiluminescence (CL) imaging immunoassays usually rely on natural enzymes as catalytic probes, which has hampered their extensive application due to the susceptibility to inactivation of natural enzymes. In response, a gold brocade coated CoFe Prussian blue analogue (CoFe PBA@Au brocade) with enhanced peroxidase-like activity was synthesized and utilized as a powerful label probe for constructing a highly sensitive CL imaging immunosensor targeting disease biomarkers with excellent performance. This research offers a universal strategy for enhancing the sensitivity of CL imaging immunoassays and further expands the application of PBA nanozymes.

Tunable Photocatalytic Activity of CoFe Prussian Blue Analogue Modified SrTiO3 Core-Shell Structures for Solar-Driven Water Oxidation.

This study presents a pioneering semiconductor-catalyst core-shell architecture designed to enhance photocatalytic water oxidation activity significantly. This innovative assembly involves the in situ deposition of CoFe Prussian blue analogue (PBA) particles onto SrTiO3 (STO) and blue SrTiO3 (bSTO) nanocubes, effectively establishing a robust p-n junction, as demonstrated by Mott-Schottky analysis. Of notable significance, the STO/PB core-shell catalyst displayed remarkable photocatalytic performance, achieving an oxygen evolution rate of 129.6 μmol g-1 h-1, with stability over an extended 9-h in the presence of S2O82- as an electron scavenger. Thorough characterization unequivocally verified the precise alignment of the band energies within the STO/PB core-shell assembly. Our research underscores the critical role of tailored semiconductor-catalyst interfaces in advancing the realm of photocatalysis and its broader applications in renewable energy technologies.

Rational design of a CoFe-prussian blue analogue-derived three-dimensional ternary nanocatalyst with efficient ORR/OER catalytic performance for Zn-air batteries

To effectively alleviate the aggregation of catalytic active sites, the rational design and simple preparation of a nanocatalyst with an ideal configuration plays a decisive role. Herein, a CoFe-prussian blue analogue (PBA) decorated with composite carbon/nitrogen sources (C/Ns) is prepared as the precursor to synthesize a three-dimensional (3D) ternary nanocomposite by a two-step calcination method. In this 3D nanocomposite, the 0D CoFe alloy nanoparticles derived from the PBA are mostly embedded in 1D N-doped carbon nanotubes (NCNTs) and partially loaded on 2D N-doped carbon nanosheets. Accordingly, the aggregation of alloy nanoparticles is greatly alleviated while a 3D nanostructure with large specific surface area, porosity, good electron transport properties and exposed active sites can be formed. The alloy nanoparticles are excellent electrocatalysts for oxygen reduction/oxygen evolution reactions, while also facilitating the formation of conductive NCNTs. Density Functional Theory calculations confirm the synergy between the Fe, N doped carbon and (110) crystal plane of the CoFe alloy that accounts for the electrocatalytic activity. The assembled Zn-air batteries show an open circuit voltage of 1.510 V, power density of 196.1 mW cm−2 and an operational durability of 300 h. Moreover, the assembled all-solid-state batteries display the potential for practical applications. This work demonstrates that the configuration of the electrocatalyst can significantly affect its catalytic performance.

Co-Fe Prussian blue analogue ultrafine nanocrystal cubes grown in-situ in honeycomb carbon as high-performance anode for lithium-ion batteries

Prussian blue analogues (PBAs) are promising anode materials for lithium-ion batteries due to the unique 3D open frameworks, but inferior cycling performance and poor rate capability restrict their application. Herein, Co-Fe PBA@honeycomb carbon is prepared by means of well-designed solution evaporation assembly and in-situ etching-coordination strategy. K0.90Co[Fe(CN)6]0.97□0.03⋅0·.44H2O (□: vacancy defect) cubes with uniform size of 20 nm are grown within every honeycomb carbon pore with a diameter of ∼ 180 nm. The mass content of Co-Fe PBA reaches 78.61 wt%. The small size, low defects and less interstitial/coordinated water improve kinetics properties and robustness of Co-Fe PBA. Honeycomb carbon further enhances the electronic conductivity and structural stability of Co-Fe PBA. Accordingly, Co-Fe PBA@honeycomb carbon exhibits high reversible capacities of 915 mAh/g at 0.5 A/g after 200 cycles, 658 mAh/g at 1 A/g after 1000 cycles, 496 mAh/g at 2 A/g after 450 cycles. Rate performance and kinetics properties are superior. The reversible capacity at 5 A/g is as high as 328 mAh/g. The diffusion coefficient of Li+ reaches 10−10.0 ∼ 10−11.7 cm2 s−1. Ex-situ scanning electron microscopy and Fourier transform infrared spectrometer demonstrate that the cycled Co-Fe PBA@honeycomb carbon is stable.

Zeolitic imidazolate framework induced CoFe-PBA/Carbides hollow cube toward robust bi-functional electrochemical oxygen reaction

The incorporation of a multi-stage porous structure in the design of bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for facilitating efficient material transport processes in zinc-air batteries (ZABs). In this work, a combination of zeolitic imidazolate framework-67 (ZIF-67) templates and acid etching techniques is employed to integrate the micropores of CoFe Prussian blue analogue (CoFe-PBA), mesopores formed by acid etching, and the macropores derived from ZIF-67 templates. This integration results in the formation of sc-PBA/Carbides@NC hollow nanobox catalysts with a multi-stage porous structure. This allows maximum exposure of active sites within the catalyst and significantly enhances material transport during electrochemical reactions. As a result, the ZAB assembled with sc-PBA/Carbides@NC catalyst shows a peak power density of 235 mW cm−2 and excellent stability, thus indicating promising prospects for practical applications.

Novel Electrochemiluminescent Immunosensor Using Dual Amplified Signals from a CoFe Prussian Blue Analogue and Au Nanoparticle for the Detection of Lp-PLA2.

Coronary heart disease (CHD) poses an important threat to human health, and its pathogenesis is the formation of atheromatous plaques in coronary ventricles. Compared to other biomarkers, lipoprotein-associated phospholipase A2 (Lp-PLA2), which is involved in multiple processes of atherosclerosis, is a noticeable inflammatory biomarker related to CHD. Herein, using a multifunctional nanocomposite containing a CoFe Prussian blue analogue (PBA) and Au nanoparticles (AuNPs) (AuNPs@CoFe PBA) as a sensing substrate, an electrochemiluminescent (ECL) immunosensor was developed for the highly sensitive detection of Lp-PLA2. Benefiting from the synergistic effect of the PBA and AuNPs, the nanocomposite exhibits excellent peroxidase-like activity and can catalyze the luminol-ECL reaction, amplifying the ECL signal by ∼29-fold. Meanwhile, the enlarged specific surface area of the nanocomposite and the presence of abundant AuNPs allow the immobilization of more antibody proteins, thereby improving the sensing response of the immunosensor. When the target Lp-PLA2 is captured by the antibody on the sensor surface, the sensor emits a reduced ECL signal because of the increased mass and electron transfer resistance due to the formation of the immune complex. Under optimized conditions, the constructed ECL immunosensor exhibits a broad linear range from 1 to 2200 ng/mL and a low detection limit of 0.21 ng/mL. Additionally, the ECL immunosensor exhibits high specificity, stability, and reproducibility. This work provides a new approach to diagnose CHD and broadened the application of the PBA in the field of ECL sensors.

High mass loading and additive-free prussian blue analogue based flexible electrodes for Na-ion supercapacitors

Supercapacitor electrodes often suffer from the low mass loading of active substances and the unsatisfactory ion/charge transport features due to the use of various additives. Exploring high mass loading and additive-free electrodes is of huge significance to develop advanced supercapacitors with commercial application prospects, which still remains challenging. Herein, high mass loading CoFe-prussian blue analogue (CoFe-PBA) electrodes are developed by a facile co-precipitation method using activated carbon cloth (ACC) as the flexible substrate. The homogeneous nanocube structure, large specific surface area (143.9 m2 g−1) and appropriate pore size distribution (3.4 nm) of the CoFe-PBA endow the as-prepared CoFe-PBA/ACC electrodes with low resistance and appealing ion diffusion characteristics. Typically, the high areal capacitance (1155.0 mF cm−2 at 0.5 mA cm−2) is obtained for high mass loading CoFe-PBA/ACC electrodes (9.7 mg cm−2). Furthermore, symmetrical flexible supercapacitors (FSCs) are constructed using CoFe-PBA/ACC electrodes and Na2SO4/polyving alcohol (Na2SO4/PVA) gel electrolyte, achieving superior stability (85.6% capacitance retention after 5,000 cycles), maximum energy density of 33.8 μWh cm−2 at 200.0 μW cm−2 and promising mechanical flexibility. This work is expected to offer inspirations for the development of high mass loading and additive-free electrodes for FSCs.

Construction and comparison of Prussian blue analogs nanomaterials with tailorable coordination metal ions as novel adsorbents for efficient structure-selective protein adsorption

Efficient and selective purify histidine (His)-rich proteins from complex biological sample for disease initiation and progression diagnostic is crucial, but it is still a challenge. Herein, for the first time, nanomaterials composed of Prussian blue analogues (PBAs) with tailorable coordination metal ions were synthesized and operated as adsorbents for selective separation of His-rich proteins. Benefiting from the strong metal affinity forces between the His residual in protein and the immobilized Cu2+, Ni2+ and Co2+ in CuFe, NiFe and CoFe PBAs, the obtained adsorbents exhibit highly selective adsorption performance for structure-selective proteins toward bovine hemoglobin (BHb). As a results, the maximum adsorption capacities of CuFe, NiFe and CoFe PBAs for BHb are 3365.8 mg g−1, 2421.3 mg g−1 and 1791.2 mg g−1, respectively. Moreover, the high-performance CuFe, NiFe and CoFe PBAs can be easily regenerated and used to effectively separation of BHb from real bovine blood samples, permitting their excellent practicality in the complex biological sample pretreatment, and further expanding the application scope of the traditional classical coordination compound in biochemical analysis fields.

Concurrently Engineered Lewis Acid Sites and Coordination Sphere Vacancies in CoFe Prussian Blue Analogues for Boosted Bifunctional Oxygen Electrocatalysis

Prussian blue analogues (PBAs), due to their high surface area, large density of catalytically active sites, and high porosity, are one of the potential bifunctional oxygen electrocatalysts for industrial applications. However, so far, only limited success has been achieved toward developing highly efficient PBA-based electrocatalysts. Therefore, unravelling the underlying structure–property–activity relationship and designing strategies or combination of tested strategies are crucial to this effect. In this work, we demonstrate a strategy to concurrently engineer the coordination sphere vacancies and Lewis acid sites, via atomically dispersed Zn2+ dopants in CoFe PBA that makes Con+ more electropositive, to boost the bifunctional oxygen electrocatalysis on PBA surfaces. The optimal Zn-doping (3 mole %) not only enhances the oxygen evolution reaction (OER) activity of CoFe PBAs to the comparable level of the IrO2 catalyst but also depicts an impressive bifunctional oxygen activity with a low reversible overvoltage of 0.84 V. This work also demonstrates that an in situ formation of Co3+ (CoOOH) and Fe3+ (FeOOH) during the OER plays a crucial role for the boosted activity in bifunctional oxygen electrocatalysis. Besides providing highly efficient and low-cost catalysts, this study also imparts important insights to improve the efficiency of PBA-based bifunctional oxygen electrocatalysis.

Moderate heat treatment of CoFe Prussian blue analogues for enhanced oxygen evolution reaction performance

Moderate heat treatment of CoFe Prussian blue analogues for enhanced oxygen evolution reaction performance

A S‐Scheme MOF‐on‐MOF Heterostructure

AbstractConstructing MOF‐on‐MOF heterojunction with elaborate charge transfer mechanism and interface is a promising strategy for improving the photocatalytic properties of MOFs. Herein, a Step‐scheme (S‐scheme) MIL‐125‐NH2@CoFe Prussian blue analogue (PBA) heterojunction is reported for the first time. The MOF‐on‐MOF heterostructure exhibits a sandwich‐like morphology with hollow CoFe PBA nanocages selectively assembled on the top‐down surfaces of MIL‐125‐NH2 nanocakes. Experimental findings and theoretical simulation results reveal the formation of internal electric field via interfacial TiOCo bonds at the heterojunction, providing driving force and atomic transportation highway for accelerating the S‐scheme charge transfer and enhancing the redox performance. Contributed further by the hollow sandwich‐like structures with increased active site exposure, the designed MOF‐on‐MOF heterojunction exhibits significantly enhanced photocatalytic activity for degradation of various organic pollutants. This study provides insights toward the rational design of semiconducting MOF‐based heterojunctions with improved properties.

CoFe Alloy-Coupled Mo2C Wrapped by Nitrogen-Doped Carbon as Highly Active Electrocatalysts for Oxygen Reduction/Evolution Reactions.

Molybdenum carbide (Mo2C) with a Pt-like d-band electron structure exhibits certain activities for oxygen reduction and evolution reactions (ORR/OER) in alkaline solutions, but it is questioned due to its poor OER stability. Combining Mo2C with transition metals alloy is a feasible way to stabilize its electrochemical activity. Herein, CoFe-Prussian blue analogues are used as a precursor to compound with graphitic carbon nitride and Mo6+ to synthesize FeCo alloy and Mo2C co-encapsulated N-doped carbon (NG-CoFe/Mo2C). The morphology of NG-CoFe/Mo2C (800 °C) shows that CoFe/Mo2C heterojunctions are well wrapped by N-doped graphitic carbon. Carbon coating not only inhibits growth and agglomeration of Mo2C/CoFe, but also enhances corrosion resistance of NG-CoFe/Mo2C. NG-CoFe/Mo2C (800 °C) exhibits an excellent half-wave potential (E1/2 = 0.880 V) for ORR. It also obtains a lower OER overpotential (325 mV) than RuO2 due to the formation of active species (CoOOH/β-FeOOH, as indicated by in-situ X-ray diffraction tests). E1/2 shifts only 6 mV after 5000 ORR cycles, while overpotential for OER increases only 19 mV after 1000 cycles. ORR/OER performances of NG-CoFe/Mo2C (800 °C) are close to or better than those of many recently reported catalysts. It provides an interfacial engineering strategy to enhance the intrinsic activity and stability of carbides modified by transition-metals alloy for oxygen electrocatalysis.

Co3+-rich CoFe-PBA encapsulated in ultrathin MoS2 sheath as integrated core-shell architectures for highly efficient OER

Highly active and stable oxygen evolution reaction (OER) electrocatalyst is the key component of sustainable water splitting reaction. Controllable core-shell engineering is one of the most effective strategies for modulating the local electronic structure of active sites to enhance catalytic activity. Herein, we design a nano-cube of Co3+-rich CoFe Prussian blue analogues coated with controllable MoS2 shell heterostructures as OER electrocatalyst by simple solvothermal method, named as CoIIIFe-PBA/MoS2. Importantly, CoIIIFe-PBA/MoS2 possesses an extremely low overpotential of 306 mV at the current density of 100 mA cm−2, a small Tafel slope of 36.2 mV dec−1 and excellent stability for OER. The results of spectroscopic characterizations reveal that the Co3+ species with more 3d electron orbits origin from the charge transfer between CoFe-PBA and MoS2 core-shell interface, which promotes the electron accepting and results in the higher electrochemical activity. This research offers unique insight to design other advanced electrocatalysts with high-valent transition metal ions and core-shell structure.