Three-dimensional Open Framework Research Articles

Multi-metal substituted Fe-based Prussian blue as high-capacity cathode material for potassium ion batteries

Fe-based Prussian blue (FePB) has been widely studied as cathode materials of potassium ion batteries due to its three-dimensional open framework structure and large ion migration channels. In this study, the effect of the introduction of various metals (Co2+, Cu2+, Ni2+, Mn2+) on the rate and cycle properties of FePB was investigated. MnCoNiFePB cathode material shows better electrochemical performance, with the initial discharge capacity of 91.3 and 75.4 mAh g−1 (capacity retention is 56.7 % after 100 cycles) at 0.2C and 1C, respectively. These results inspire new ideas for the development and application of potassium ion battery electrode materials.

High-Entropy Prussian Blue Analogues as High-Capacity Cathode Material for Potassium Ion Batteries

Potassium ion batteries, due to their similar electrochemical principles to lithium-ion batteries and the abundance of metal sources, are considered one of the alternatives to lithium-ion batteries. The development of new cathode materials has always been a research focus in this field. Among them, Prussian blue materials, with their three-dimensional open and flexible metal framework structure, can efficiently and reversibly store potassium ions. However, Prussian blue cathode materials still face issues such as poor reversibility and low capacity, which limit their application scope. This study investigates the preparation of high-entropy Prussian blue analogues materials to enhance electrochemical performance. The doping of five different transition metals (Fe2⁺, Co2⁺, Cu2+, Ni2+, and Mn2+) sharing the same nitrogen coordination sites results in a configurational entropy greater than 1.5 R for the material. HEPB-1 cathode material (K1.75Mn0.26Fe0.01Ni0.01Cu0.08Co0.09 [Fe(CN)6]0.66·0.83H2O) shows better electrochemical performance, with the initial discharge capacity of 86.69 and 74.51 mAh g−1 (capacity retention is 75.2% after 100 cycles) at 20 and 100 mA g−1, respectively. The research results have provided new insights for the further development and application of potassium ion batteries.

Polyaniline-modified amorphous tin-based Prussian blue analogue as cathodes for long-life aqueous zinc ion batteries

Prussian blue analogs (PBAs) have emerged in the field of aqueous zinc ion batteries (AZIBs) owing to their simple synthesis method and three-dimensional open framework structure. Although PBAs have high redox potentials, the unsatisfactory specific capacity and poor electrical conductivity limit their development to some extent. In this work, amorphous tin hexacyanoferrate (SnHCF) and polyaniline (PANI) were combined to form SnHCF/PANI composite. The synergistic effect of the amorphous structure of SnHCF and PANI with good conductivity makes the SnHCF/PANI electrode exhibit excellent redox activity and achieve rapid ion/electron transfer. When used as a cathode in AZIBs, the SnHCF/PANI provides a high specific capacity (136.8 mAh g−1 at 0.5 A g−1) and excellent cycling stability (a discharge specific capacity of 54.3 mAh g−1 after 2500 cycles at 2 A g−1). This work offers a new idea for the development of PBAs-based composites as cathode materials for AZIBs.

Aqueous cerium ion battery: A novel aqueous rechargeable battery

Aqueous rechargeable batteries (ARBs) are a potential energy storage system with lowcost aqueous electrolyte and high safety. Multivalent host carriers in electrolyte can offer a wider variety of valence states and redox properties leading to high capacity. In this work, an aqueous cerium ion aqueous (ACIBs) battery has been reported with a satisfactory electrochemical performance for the first time. By utilizing the advantages of stable structure and three-dimensional (3D) open framework of Prussian blue analogues (PBAs), the problem of cerium ions insertion/de-insertion into host materials due to high charge and large size can been successfully solved. Herein, the copper hexacyanoferrate (CuPBA) is prepared through a facile coprecipitation strategy as cathode material of ACIBs. The CuPBA cathode deliver a satisfactory capacity (79 mAh g−1 at 50 mA g−1) and an excellent cycling stability after long-time cycles (86.8 % capacity retention after 5000 cycles at 1000 mA g−1). As a result, the cathode material in ACIBs system displays excellent rate capability and cycling performance. The successful assemble of the full battery also verifies the feasibility of ACIBs. In addition, the energy storage mechanism of Ce3+ ion insertion/de-insertion process is explained by ex situ X-ray diffraction and X-ray photoelectron spectroscopy measurements. This work opens up a new direction and provides a foundation for development of novel ARBs.

A Comprehensive Review on Strategies for Enhancing the Performance of Polyanionic-Based Sodium-Ion Battery Cathodes.

The significant consumption of fossil fuels and the increasing pollution have spurred the development of energy-storage devices like batteries. Due to their high cost and limited resources, widely used lithium-ion batteries have become unsuitable for large-scale energy production. Sodium is considered to be one of the most promising substitutes for lithium due to its wide availability and similar physiochemical properties. Designing a suitable cathode material for sodium-ion batteries is essential, as the overall electrochemical performance and the cost of battery depend on the cathode material. Among different types of cathode materials, polyanionic material has emerged as a great option due to its higher redox potential, stable crystal structure, and open three-dimensional framework. However, the poor electronic and ionic conductivity limits their applicability. This review briefly discusses the strategies to deal with the challenges of transition-metal oxides and Prussian blue analogue, recent developments in polyanionic compounds, and strategies to improve electrochemical performance of polyanionic material by nanostructuring, surface coating, morphology control, and heteroatom doping, which is expected to accelerate the future design of sodium-ion battery cathodes.

A Three-Dimensional Open-Framework Tin(II) Sulfate with Near-Unity Photoluminescence Quantum Yield.

A new open-framework tin(II) sulfate, formulated as C4H12N2·Sn(SO4)2·H2O, was prepared under the structure-directing effect of piperazine. This compound features a 3D structure with 16-ring channels. Under ultraviolet light irradiation, it emits bright yellow luminescence with a near-unity photoluminescence quantum yield. Theoretical calculations were carried out to understand the luminescence mechanism.

Prussian blue analogue-based superstructure nanoarrays for sodium ion hybrid supercapacitors

Supercapacitors (SCs) have attracted significant attention due to their remarkable traits of high-power density and prolonged cyclability. Despite the extensive exploration of Prussian blue analogues (PBAs) with three-dimensional (3D) open frameworks as SC electrodes, their instability and low conductivity have impeded their advancement in practical SC applications. In this study, we present a straightforward immersion-based technique to produce a superstructure nanoarray of CoNiFe-based PBA (CoNiFePBA). The unique superstructure comprises ultrathin nanosheets assembled into a half-open hollow configuration, fostering abundant active surface sites, a stable framework, and efficient channels for ion/electron transfer, consequently enabling effective charge storage. Furthermore, the integration of ternary metals not only offers numerous redox reaction centers but also heightens synergistic effects, resulting in enhanced capacity and cycling stability. As a result, the CoNiFePBA electrode delivers outstanding specific capacity (96.85 mAh g−1 at 0.5 A g−1) and enduring cycling stability (92.25 % after 10,000 cycles). Notably, the hybrid SC built on the CoNiFePBA demonstrates an exceptionally broad voltage window (2.1 V) and a high energy density. This work underscores the immense potential of CoNiFePBA superstructure nanoarrays for driving high-performance SC technology forward.

Cheverl phase Mo6Te8 nanoparticles as new anode materials for lithium-ion batteries

Lithium-ion batteries have become increasingly indispensable as a kind of energy conversion and storage device. Cheverl phase materials show potential advantages over transition metal chalcogenides in lithium-ion batteries, owing to their high three-dimensional open frameworks and good tolerance to a large current. Herein, Chevrel phase Mo6Te8 has been synthesized by high-temperature solid-phase reaction and modified with dopamine, resulting in Carbon and Nitrogen atoms anchored on the Mo6Te8 surface. During the C/N doping process, due to lattice gap and vacancy defects, C/N itself is adsorbed in the vacancy or lattice gap, resulting in lattice expansion, which makes the process of lithium ion deintercalation smoother. Compared with the original Mo6Te8, the specific capacity and conductivity of the composite Mo6Te8@C/N have significantly improved. With a maximum specific capacity close to 812 mAh g−1 at a current density of 0.1 A g−1 and a maximum capacity close to 436 mAh g−1 at a high current density of 1 A g−1, the excellent conductivity of Mo6Te8@C/N contributes to the diffusion of Li+, and the increased active site improves the efficiency of electron transfer. The direct comparison between MoTe2 and Mo6Te8@C/N clearly supports the advantages of Chevrel phase materials in batteries.

Phytic acid-modified NiFe-PBA stacked by π-π force for reinforcement electrocatalytic water oxidation

Prussian blue analogues (PBAs) with unique three-dimensional (3D) open metal framework structure and easily adjustable composition have been widely used in oxygen evolution reaction (OER) under alkaline conditions. Herein, disintegrative...

The Synthesis and Characterization of Pahae Natural Zeolite-Coal Bottom Ash Adsorbent for Fe and Mn Purifier in Well Water

Zeolite is a porous crystalline mineral alumina silica tetrahydrate that has an open three-dimensional framework structure that has channels and cavities filled with metal ions, while Bottom ash is also known to have high porosity and surface area. Thus, both zeolite and bottom ash can be used as adsorbents. This study aims to make an adsorbent based on Pahae natural zeolite with a mixture of bottom ash from coal as an adsorbent for iron (Fe) and manganese (Mn) metals in well water. Adsorbent made from Natural Zeolite Pahae-Coal Bottom Ash with a size of 200 mesh (74 µm) which has been chemically activated with 1 M NaOH solution, was prepared with various compositions of (100:0)%, (95:5)%, (90:10)%, (85:15)%, (80:20)%, (75:25)% respectively, then mold using a hydraulic press with a load of 6 tons of weight for 10 minutes. The mold samples were then physically activated with temperature variations of 600°C, 700°C, and 800°C for 4 hours, respectively. The addition of coal bottom ash filler is known to increase the porosity of the adsorbent with the composition of (75:25)% with an activated temperature of 800°C by 10%. The results of the AAS test showed that the adsorbent made from Natural Zeolite Pahae-Coal Bottom Ash reduced the content of Fe and Mn metals by 92.37% and 53.49% in well water, respectively.

Fully fluorinated hybrid zeolite imidazole/Prussian blue analogs with combined advantages for efficient oxygen evolution reaction

Hybrid metal-organic framework (MOF) derivatives play a significant role in the novel catalyst development in energy conversion reactions. Here, we demonstrated the low-temperature fully fluorinated zeolitic imidazole framework (ZIF) coupled with a three-dimensional open framework Prussian blue analog (PBA) with combined advantages for electrocatalytic oxygen evolution reaction (OER) in water splitting reaction. The spectroscopic analysis and the electrochemical studies revealed the combined advantages of efficient electronic effect and active site synergism. Because of good conductivity improvement by N-doped carbon derived from ZIF and the high electrochemical surface area and active site exposure from PBA derivatives, good catalytic performance was obtained on the optimal catalyst of CoNi ZIF/CoFe-PBA-F-300, which required a low overpotential of 250 mV to reach 10 mA/cm2 loaded on the glassy carbon electrode, with Tafel slope of 47.4 mV/dec, and very high dynamic and steady stability. In addition, the multi-component with the mixed structure from highly polar metal fluorides promoted the easy formation of the active phase as revealed by the post-sample analysis. The current results showed a novel composite catalyst materials development from the hybrid MOF derivatives, which would be promising in the electrolysis of water oxidation reactions and energy-relevant catalysis reactions.

Tailoring the growth of iron hexacyanoferrates for high-performance cathode of sodium-ion batteries

Iron hexacyanoferrate (FeHCF) is regarded as a promising cathode material of sodium-ion batteries (SIBs) due to the merits of easy preparation, low cost and three-dimensional open framework. However, the practical application of FeHCF is highly restricted by the intrinsic [Fe(CN)6]4- vacancy and coordinated water as well as nanoscale particles. Herein, sodium citrate is introduced to mediate the drawbacks of FeHCF, resulting in microscale particles with less water content. Accordingly, the modified sample, FeHCF-3, achieved the performance of 92 mA h g−1 at 100 mA g−1 and 80 % capacity retention after 300 cycles. Furthermore, an optimal iron hexacyanoferrate (FeHCF-H-2) with high-salt-concentration preparation is designed and performs a good reversibility of 96 mA h g−1 after 700 cycles at 100 mA g−1. Such strategy may drive the application of high-tap, low-defect and stable cathode for SIBs.

Thermal expansion investigation of new langbeinite type phosphomolybdates: K2-xZr2P2-xMoxSiO12 (x = 0, 0.1, 0.2)

Members of A2(MO4)3 structure type have been identified as negative thermal expansion (NTE) materials. Specifically, tungstates (Sc2(WO4)3) and molybdates (Al2(MoO4)3) with orthorhombic structure exhibits NTE due to the transverse thermal vibration of A-O-M linkage. Langbeinite is a similar type structure consist of three-dimensional open framework with MO6 octahedral and PO4 tetrahedral interconnection. In the present work, we synthesized orthorhombic phosphomolydates of the chemical formula K2-xZr2P2-xMoxSiO12 (x = 0, 0.1, 0.2) to develop new low/zero/NTE materials with langbeinite structure. The compounds were synthesized by solution method and characterized by powder XRD, FT-IR, SEM and TG-DTA. Least square refinement method revealed that the synthesized compounds are crystallize in orthorhombic structure with P212121 space group. The characteristic stretching and bending vibrational bands of P-O, Si-O and Mo-O are observed from the FT-IR spectra. The compounds are thermally stable up to 600 °C and the effect of Mo substitution is observed from the micrographs with particle size variation. In contrary to A2(MO4)3 structure type, the average thermal expansion coefficient of K1.9Zr2Mo0.1P1.9SiO12 and K1.8Zr2Mo0.2P1.8SiO12 are found to be 8.19 and 6.89 × 10-6/ °C.

Dual-salt assisted synergistic synthesis of Prussian white cathode towards high-capacity and long cycle potassium ion battery

Prussian blue analogues (PBAs) are considered as superior cathode materials for potassium-ion batteries (PIBs) because of their three-dimensional open framework structure, high stability, and low cost. However, the intrinsic lattice defects and low potassium content typically results in poor rate and cycling performance, thus limited their practical applications. In this work, high-quality K1.64FeFe(CN)6 (PW-HQ) material with less crystalline water (6.21%) and high potassium content (1.64 mol−1) was successfully synthesized by a novel coprecipitation method with potassium citrate (K-CA) and potassium chloride (KCl) addition. Specifically, the electrode delivers a reversible capacity of 113.1 mA h g−1 at the current rate of 50 mA g−1 with ∼100% coulombic efficiency. Besides, the electrode retained 90% reversible capacity at 500 mA g−1 current density after 1000 cycles, indicating only 0.01% capacity decay per cycle. Moreover, we have revealed that the introduction of K-CA controlled the chelating rate of Fe(II) and the addition of KCl increased the K+ content, hence improving the capacity and stability of the as-prepared electrodes. Structural evolution and potassium storage mechanism were further investigated by detailed ex-situ X-ray diffraction and in-situ Raman measurements, which demonstrated reversible potassiation/depotassiation behavior and negligible volume change during the electrochemical process. In general, this work provides an efficient strategy to eliminate water contents in Prussian blue cathode and improve its electrochemical performance, which plays a key role in promoting the industrialization of potassium ion batteries.

Boosting sodium-storage behaviors of NASICON-type NaTi2(PO4)3 anode by synergistic modulations in both materials and electrolytes towards aqueous Na-ion batteries

NASICON-type NaTi2(PO4)3 (NTP) is one of the most competitive anode materials for aqueous sodium-ion batteries (ASIBs), thanks to its unique three-dimensional open framework structure, high ionic conductivity and good chemical stability. However, the low electrical conductivity of NTP and the oxygen reduction induced side reactions seriously affect its practical applications. To well address the above issues, the synergistic regulation strategy in electrode materials and electrolytes is motivatively put forward. The porous single-crystal NTP micro-sized framework coated with conductive carbon nano-layer (denoted as NTP@C) is designed with significantly improved electronic conductivity and structural stability. With further regulations in both the dissolved oxygen content and pH values of aqueous Na2SO4 electrolyte, the enhanced reversible capacities and cyclic stability especially at high rates are achieved by effectively alleviating side reactions. As a result, the fabricated NTP@C anode is optimized with a high-rate capability and remarkable long-duration electrochemical stability in the N2-purged aqueous Na2SO4 electrolyte with pH = 8.0. Furthermore, the assembled NTP@C//Na0.44MnO2 ASIBs exhibit high energy density of ∼40.0 Wh kg‒1 along with excellent cycling stability. More significantly, our work provides an insightful guideline for rational construction of other advanced aqueous rechargeable batteries.

Unlocking fast and highly reversible sodium storage in Fe-based mixed polyanion cathodes for low-cost and high-performance sodium-ion batteries

The iron-based polyanionic material Na3Fe2(PO4)P2O7is regarded as an excellent cathode due to its outstanding thermal stability and the three-dimensional (3D) open framework structure with facile sodium-ion transport.

One-step superficial electrodeposition of nickel-cobalt-sulfide for high-energy hybrid asymmetric supercapacitor

A cathodic electrodeposition (ED) technique is adopted to grow multi-component nickel–cobalt-sulfide (NCS) nanosheet arrays on highly conducting nickel foam substrate. The chronoamperometry (CA) deposited electrode has shown exceptional electrochemical activity in terms of specific capacity, rate capability and excellent redox reversibility than the cyclic voltammetry (CV) deposited electrode. Having the benefit of highly conductive nanosheet arrays and three-dimensional open framework of the nanostructure, the binary metal sulfide exhibits high specific capacity of 820 C g−1 at 2 A g−1. When the NCS electrodes were combined with boron-doped graphene oxide to form an asymmetric hybrid supercapacitor, it delivered a high energy density of 83 Wh g−1 and high-power density of 9619 W kg−1.

Flexible brushite/nanofibrillated cellulose aerogels for efficient and selective removal of copper(II)

To achieve efficient removal of copper(II) from heavy metal wastewater, designing an eco-friendly and low-cost adsorbent is highly desirable. Here, a novel air- and underwater shape-memory cellulose aerogel was reported via coupling brushite and polyethyleneimine (PEI)-modified nanofibrillated cellulose (NFC) for selectively adsorbing Cu(II) ions. The adsorption kinetic and isotherm studies were consistent with pseudo-second-order model and Langmuir model, indicating the removal of Cu(II) was a monolayer chemisorption process. Benefiting from the open three-dimensional (3D) framework structure and abundant exposed active sites, such compressible aerogel exhibited excellent adsorption capacity of 332.66 mg/g for Cu(II). In addition, the developed aerogel could be conveniently used as a continuous flow filter for successive purification of industrial wastewater, where the up-to-standard treatment volume was about 5.6 L. The Cu(II)-loaded aerogel could be regenerated after being eluted by 0.1 M EDTA-2Na, and its structure, shapeability and selective adsorption properties were hardly affected even after 8 consecutive cycles. Mechanistic analysis confirmed that the surface complexation, ion exchange and chemical deposition were the main driving forces for the superior adsorption performance. Finally, PNFCA/BRU could inhibit the contamination of crops by heavy metals, which was a great safeguard for wheat growth.

Open-Framework Iron Fluoride Phosphates Based on Chain, Trinuclear, and Tetranuclear Chain FeIII Building Units: Crystal Structures and Magnetic Properties.

We report the synthesis and characterization of a series of new open-framework iron fluoride-fluorophosphates based on linear, trinuclear, and tetranuclear chain FeIII building units. KFe2(PO3F)2F3 (I) consists of {Fe2(O3F)2F2}10- zigzag chains interconnected by P(O/F)4 tetrahedra forming a three-dimensional (3D) open framework. K2Fe(PO2.5F1.5)2F2 (II) is built up by {Fe(PO2.5F1.5)2F2}2- chains separated by K+ cation layers. The framework for K3Fe3(PO4)(PO3F)2F5 (III) contains two-dimensional {Fe3O4F4(PO3F)2}2- sheets, which are built from trimeric Fe-octahedra insulated by PO3F tetrahedra. The macroanionic framework of K3Fe4(PO4)2F9 (IV) comprises linear {Fe4O8F9}10- chains consisting of tetranuclear magnetic clusters of [Fe4O8F9]10- formed via corner-sharing fluorine atoms decorated with PO4 groups. The magnetic characterization of three iron fluorophosphates reveals diversified magnetism: S = 5/2 spin chains for I, antiferromagnetically coupled triangular Fe units for III, and coupled tetrahedral S = 5/2 spin chains for IV. IV shows strong geometric frustration thanks to its spin motifs of corner-shared tetrahedral clusters.

Reducing atmosphere improves the conductivity of NaTi2(PO4)3/C material for hybrid aqueous rechargeable lithium-ion battery anode

Hybrid aqueous rechargeable lithium-ion batteries (HARLIBs) have lower cost and better safety performance than conventional lithium-ion batteries (organic electrolytes). The challenge faced by HARLIBs are the narrow selection of anode and cathode materials, and overcoming the problems of capacity decay of anode and cathode materials in aqueous electrolytes. NaTi2(PO4)3, which has a stable three-dimensional open framework structure, shows certain applicability in HARLIBs, but its inherent low electronic conductivity leads to poor utilization of active materials and inferior rate performance. In this article, we propose an experimental method that can improve the conductivity of NaTi2(PO4)3/C, and study the electrochemical performance of NaTi2(PO4)3/C aqueous half-cell and NaTi2(PO4)3/C||LiMn2O4 hybrid aqueous full cell. The results show that Ti3+/oxygen vacancies can endow NaTi2(PO4)3/C with higher conductivity and improve the specific capacity and rate capability (69 mAh·g−1, 7C). At 1C, the second discharge specific capacity is 98.46 mAh·g−1. After 100 cycles, the Rct was 2.92 × 10−2 Ω. The NaTi2(PO4)3/C//LiMn2O4 full cell can provide a discharge specific capacity of up to 101.07 mAh·g−1. The synthesized NaTi2(PO4)3/C material can be applied to the anode electrode of hybrid aqueous lithium-ion full cell.