Metal-organic framework-derived transition metal sulfides and their composites for alkali-ion batteries: A review

Advanced Alkali Metal Batteries Based on MOFs and Their Composites

The integration of metal-organic frameworks (MOFs) with functional materials has established a versatile platform for a wide range of energy storage applications. Due to their large specific surface area, high porosity, and tunable structural properties, MOFs hold significant promise as components in energy storage systems, including electrodes, electrolytes, and separators for alkali metal-ion batteries (AIBs). Although lithium-ion batteries (LIBs) are widely used, their commercial graphite anode materials are nearing their theoretical capacity limits, and the scarcity of lithium and cobalt resources increases costs. Although zinc-ion batteries (ZIBs) suffer from limited cycling stability, they are attractive for their low cost, high capacity, and excellent safety. Meanwhile, potassium-ion (PIBs) and sodium-ion batteries (SIBs) show promise due to their affordability and abundant resources, but they encounter issues such as short cycle life and low energy density. This review outlines the applications of MOF composites in LIBs, SIBs, and ZIBs, introduces common synthesis methods, and forecasts future development directions and challenges in energy storage applications. We emphasize how the understanding can lay the foundation for developing MOF composites with enhanced functionalities.

Modulation of Surface/Interface States in Bi2S3/VS4 Heterostructure With CN Layer for High-Performance Sodium-Ion Batteries: Enhanced Built-in Electric Field and Polysulfide Capture

Metal sulfides are promising materials for sodium-ion batteries (SIBs) owing to unique structures and high theoretical capacity. However, issues like poor conductivity, large volume changes, and polysulfide dissolution limit practical application. This study introduces a novel Christmas tree-like heterostructure composed of Bi2S3 and VS4 encapsulated in nitrogen-doped carbon shell (Bi2S3/VS4@CN), synthesized by sulfurizing dopamine-coated BiVO4 precursor. The in situ synthesis ensures excellent lattice matching between Bi2S3 and VS4, minimizing interface states and enhancing effective built-in electric field. This design accelerates electrochemical reaction kinetics; moreover, it promotes progressive reaction that mitigates structural fragmentation, suppresses degradation, and prevents polysulfide dissolution and shuttle. Additionally, the CN shell effectively passivates the surface states of Bi2S3 and VS4 nanostructures, lowering surface barrier and improving overall conductivity. As a result, Bi2S3/VS4@CN-based half-SIBs demonstrate remarkable long-cycle stability, maintaining 387.1 mAh g-1 after 1600 cycles at 2 A g-1, and excellent rate performance with 376.3 mAh g-1 at 5 A g-1. Full-SIBs using Na3V2(PO4)3//Bi2S3/VS4@CN exhibit outstanding cycling stability, retaining 117.2 mAh g-1 after 200 cycles at 1 A g-1, along with 218 Wh kg-1 high energy density at 145.3 W kg-1. This work highlights the potential of heterostructures in advancing metal sulfide-based SIBs for high-performance energy storage.

In Situ Phase Transformation of Nanoporous Fe2O3 Dendrite to Fe2O3/FeS2 Polycrystalline Texture Achieving Superior Rate Capability and Ultra-Long Cycling Stability with High Capacity

Structural design combined with crystal engineering is an external and internal modifying strategy for metal oxides and sulfides as anode materials for lithium/sodium-ion batteries (LIBs/SIBs). In this paper, the low-cost iron-based oxide of Fe2O3 shaped into dendritic nanostructure is locally in situ phase converted to FeS2 and form porous Fe2O3/FeS2 polycrystalline texture. The Fe2O3/FeS2 maintains the original porous, cross-linked and low-dimension structural advantages of the Fe2O3 precursor for electron transport and ions exchange and alleviating volume expansion. Then, the abundant heterogeneous in the converted Fe2O3/FeS2 dramatically enhances electron diffusion in crystal and the structural stability at phase boundary. The prepared anode achieves superior rate capability and ultra-long cycling stability with high capacity both in LIBs and SIBs. Specially, it shows 1017 and 1016 mAh g-1 at 10 A g-1 in LIBs and SIBs, separately. After 3000 cycles, the electrodes maintain 266 mAh g-1 at 10 A g-1 in LIBs and 279 mAh g-1 in SIBs. In addition, the LiFePO4//Fe2O3/FeS2 and (Na3V2(PO4)3)//Fe2O3/FeS2 full cells are successfully packaged and also show satisfactory electrochemical performances.

Integrating Competitive Li+ Coordination with Immobilized Anions in Composite Solid Electrolyte for High-Performance Li Metal Batteries

Poly(vinylidene fluoride) (PVDF)-based polymer electrolytes have attracted widespread attention due to their unique Li+ transport mechanism. However, their low ionic conductivity and porous structure, as well as residual solvent limit their application at high current densities. Here, a composite solid electrolyte (CSE) is developed by integrating poly(vinylidene-co-trifluoroethylene) [P(VDF-TrFE)] in its all-trans conformation with aminofunctionalized metal-organic framework (ZIF-90-NH2). In such a CSE, all F atoms located on one side of the polymer chain, providing fast Li+ transport channels. Concurrently, the functionalized ZIF-90-NH2 can effectively anchor the residual N, N-dimethylformamide (DMF) in CSEs while weakening Li+-DMF solvent coordination, inducing the rearrangement of Li+ solvation structure and inhibiting the decomposition of DMF at the interface. Synergistically, ZIF-90-NH2 can immobilize anions in Li salts, promoting their dissociation. Based on integrating competitive Li+ coordination with immobilized anions, the obtained CSEs exhibit a high Li+ transference number (0.77). The full cells with LiFePO4 cathode can run stably over 400 cycles at 5 C, while the Li || LiNi0.7Co0.1Mn0.2O2 full cells deliver a high capacity retention (>85%) after 200 cycles at a charge cutoff voltage of 4.5 V. This work opens up a new path for building CSEs with high interfacial stability and fast Li+ transport.

An electrochemical biosensor for the detection of BRCA1 based on MOF-derived CeO2@CuS nanosheets with high electrocatalytic H2O2 reduction performance

BACKGROUND

Since the incidence of breast cancer ranks first among female malignant tumors, early diagnosis and treatment of breast cancer are crucial to women's health. Therefore, the detection and monitoring of breast cancer susceptibility gene (BRCA1) is particularly important. In this paper, an electrochemical biosensor was developed to detect BRCA1 based on MOF-derived CeO2@CuS nanosheets with efficient electrocatalytic activity of H2O2 reduction.

RESULTS

CeO2 nanotube derived from MOF possessed excellent charge transfer ability and high specific surface area, making it an ideal substrate for loading CuS nanosheets. The combination of CeO2 and CuS enhanced the electrocatalytic activity and conductivity of H2O2 redox reaction. Then gold nanoparticles (Au) were introduced to synthesize Au@CeO2@CuS to further improve conductivity and electrocatalytic activity. Based on the excellent properties of the above synthetic materials, the non-enzymatic electrochemical sensing platform for detecting BRCA1 were constructed. The proposed method demonstrated wide linearity ranges and low detection limits for detecting BRCA1 (0.1 pmol/L - 10 nmol/L, 0.02 fmol/L), respectively.

SIGNIFICANCE

These showed that the sensing strategy provides a new approach for the detection of BRCA1 and has important significance for the early diagnosis and treatment of breast cancer.

Bimetal-organic framework-templated Zn-Fe-based transition metal oxide composites through heterostructure optimization to boost lithium storage

Transition metal oxides (TMOs), especially zinc- and iron-based materials, are known to be one of the most innovative anode materials based on their high theoretical capacity, low price and abundant natural reserves. However, the application of these materials is limited by poor electronic conductivity, slow ion mobility and large structural transformations during charging/discharging processes. To overcome these drawbacks, sacrificial template technology has been proposed as a promising strategy to optimize the electrochemical performance and structure stability of TMOs, showing its potential especially in the storage design of lithium-ion batteries (LIBs). In this paper, we successfully synthesized a series of ZnFe2O4/Fe2O3 compounds (named as ZFFO) with Zn/Fe-MOFs (metal-organic frameworks) as sacrificial templates, and then obtained single-component ZnFe2O4 contrast samples (named as ZFO) by etching ZFFO with NaOH. Density Functional Theory (DFT) calculations display that the bi-component ZFFO materials formed by the introduction of Fe2O3 exhibit a lower Li+ migration energy barrier compared to the single-component ZFO materials, indicating better ion diffusion kinetics of ZFFO. The bi-components of ZnFe2O4 and Fe2O3 in ZFFO electrodes can exert a synergistic effect to achieve mutual constraints on volume expansion and alleviate volume strain during charging/discharging processes, thus improving structural stability and electrochemical performance. Besides, the ZnFe2O4/Fe2O3 constructed with 2-methylimidazole as a ligand not only has the synergistic effect of bi-components, but also exhibits a uniformly distributed small-size particle morphology, so that the discharge capacity is 864.2 mAh g-1 after 200 cycles at 0.1 A g-1 when used as an anode for LIBs. This approach presents a feasible and efficient way to synthesize bi-component transition metal oxides with improved practical applications for LIBs.

RuCo@C Hollow Nanoprisms Derived from ZIF-67 for Enhanced Hydrogen and Oxygen Evolution Reactions

Zeolitic imidazolate frameworks (ZIFs) are commonly used to create complex hollow structures for energy applications. This study presents a simple method to produce a novel hollow nanoprism Co@C hierarchical composite from ZIF-67 through high-temperature treatment at 800 °C. This composite serves as a platform for Ru nanoparticle deposition, forming RuCo@C hollow nanoprism (RuCo@C HNP). As an electrocatalyst in 1 M KOH, RuCo@C HNP exhibits excellent hydrogen evolution reaction (HER) performance, with a low overpotential of 32 mV to reach 10 mA cm-2, a Tafel slope of 39.67 mV dec-1, a high turnover frequency (TOF) of 3.83 s-1 at η200, and stable performance over 50 h. It also achieves a low η10 of 266 mV for the oxygen evolution reaction (OER) with a Tafel slope of 45.22 mV dec-1. Density functional theory (DFT) calculations reveal that Ru doping in Ni/Co maintains a low water dissociation barrier, reduces the energy barrier for the OER rate-determining step, and creates active sites for H*, enhancing adsorption/desorption abilities. These results are attributed to the synergy between Co and Ru and the hollow prism structure's increased surface area. This method for synthesizing hollow structures using ZIF composites shows promise for applications in the energy sector.

Synthesis of metal-organic framework-luminescent guest (MOF@LG) composites and their applications in environmental health sensing: A mini review

Metal-organic framework (MOF) materials are three-dimensional structures formed by the combination of metal ions and organic ligands. So far, various typical metal organic framework materials have emerged, such as ZIF-8, MOF-5, UIO-66, etc. These traditional MOF materials have the advantages of simple synthesis, high porosity, and high stability, and have great research potential in the field of fluorescence sensing. However, MOF materials with excellent luminescent properties often involve fine regulation of organic ligands to ensure that fluorescence emission can be achieved between metal ions and organic ligands through energy transfer and photo induced electron transfer. The long synthesis cycle and cumbersome preparation process pose challenges for the research of fluorescent MOF materials. Combining MOF materials with luminescent guests is an effective way to prepare simple fluorescent chemical sensors. These luminescent guests include quantum dots, organic dyes, fluorescent nanoparticles, etc. They have the characteristic of high luminescence quantum yield, but high concentrations often lead to aggregation and collision, which in turn cause emission quenching. MOF materials with excellent porosity and specific surface area can serve as an ideal platform for encapsulating luminescent guests and preventing their aggregation. The preparation of MOF@luminescent guest composite material (MOF@LG) is easy to synthesize, which not only effectively improves the poor fluorescence performance of MOFs themselves, but also preserves the excellent fluorescence performance of luminescent guests. Composite materials often have excellent solid-state luminescence performance, making them a good choice for constructing a simple fluorescence sensing platform.

Advanced Bismuth-Based Anode Materials for Efficient Potassium Storage: Structural Features, Storage Mechanisms and Modification Strategies

Potassium-ion batteries (PIBs) are considered as a promising energy storage system owing to its abundant potassium resources. As an important part of the battery composition, anode materials play a vital role in the future development of PIBs. Bismuth-based anode materials demonstrate great potential for storing potassium ions (K+) due to their layered structure, high theoretical capacity based on the alloying reaction mechanism, and safe operating voltage. However, the large radius of K+ inevitably induces severe volume expansion in depotassiation/potassiation, and the sluggish kinetics of K+ insertion/extraction limits its further development. Herein, we summarize the strategies used to improve the potassium storage properties of various types of materials and introduce recent advances in the design and fabrication of favorable structural features of bismuth-based materials. Firstly, this review analyzes the structure, working mechanism and advantages and disadvantages of various types of materials for potassium storage. Then, based on this, the manuscript focuses on summarizing modification strategies including structural and morphological design, compositing with other materials, and electrolyte optimization, and elucidating the advantages of various modifications in enhancing the potassium storage performance. Finally, we outline the current challenges of bismuth-based materials in PIBs and put forward some prospects to be verified.

Novel Electrochemical Approaches for Anticancer Drug Monitoring: Application of CoS@Nitrogen-Doped Amorphous Porous Carbon Composite in Nilotinib Detection

A novel composite containing CoS and nitrogen-doped amorphous porous carbon (NAPC), denoted as CoS@NAPC, was successfully synthesized from a mixture of cobalt-based ZIF-12 and sulfur through one-pot pyrolysis. The morphology and microstructure of the composites are evaluated with appropriate spectroscopic techniques. CoS@NAPC was used to modify the glassy carbon electrode (GCE) to detect Nilotinib. Under optimized conditions, the GCE electrode modified with CoS@NAPC showed a low limit of detection (LOD) of 11.8 ng/mL and two wide linear concentration ranges of 59.7-1570 and 1570-11200 ng/mL for the determination of Nilotinib. GCE electrode modified with CoS@NAPC has excellent recoveries ranging from 98.41 to 102.03% for real samples, demonstrating its superior analytical performance. The enhanced performance of CoS@NAPC as an electrochemical sensor may stem from the combined action of two key components: CoS, known for its potent reactivity toward Nilotinib, and NAPC, which offers a consistent conductive carbon matrix. CoS contributes to its reactivity, while NAPC facilitates electron transfer during Nilotinib detection. This synergistic effect likely underlies the superior sensor performance observed.

Enhanced Structural VS4 Grown onto Hollow Carbon Mesoporous Spheres via Surficial Bonding for High Cycling Stability in Sodium-Ion Batteries

Transition metal sulfides are recognized as an excellent alternative to sodium ion anodes ascribed to the outstanding theoretical capacity. The unique crystal arrangement of VS4 gives it exceptional theoretical capacity, despite challenges like insufficient electrical conductivity and undesirable volume expansion. Herein, a novel stabilized anode featuring a distinctive 3D hollow spherical structure is proposed, providing a simple strategy to synthesize such anodes for VS4-HCMSs bonded via C-O-S and V-O-C interfaces. The kinetic investigations and density functional theory reveal that the unique structure connected by interfacial bonds enhances Na+ transport rate and charge transfer efficiency, while carbon greatly mitigates the volume expansion. Unsurprisingly, the VS4-HCMSs exhibit an impressive first-cycle Coulombic efficiency of 91.31% and an ultrahigh reversible capacity of 612 mAh g-1 after 300 cycles at 0.5 A g-1, even exhibit the reversible capacity of 498.8 mAh g-1 after 1000 cycles at 5 A g-1. Additionally, the NaFePO4//VS4-HCMSs full cell is cycled for 200 cycles at 0.2 C and powered the light-emitting diodes for up to 30 minutes afterward. Overall, this work enhances the conductivity and stability of the material by combining VS4 with hollow carbon mesoporous spheres through interfacial bonding, offering an efficient strategy to anode materials in sodium-ion batteries.

Hollow transition metal chalcogenides derived from vanadium-based metal organic framework for hybrid supercapacitors with excellent energy-density and stability

In-situ synthesized hollow transition metal chalcogenides have gained significant attention on account of their excellent electrochemical properties. Here, Ni-doped V-MOF (V(Ni)-MOF) nanorod arrays as precursor are first grown on nickel foam (NF). Subsequently, the nanorod arrays are converted into V(NiCo)-OH hollow nanotube arrays with cross-linked nanosheets by Co2+ etching. Finally, V(NiCo)-OH/NF is converted into V(NiCo)-X/NF (X = O, S and Se) by annealing or ion exchange. Due to the unique morphology of hollow nanotube arrays with cross-linked nanosheets and synergistic effect of multi-metal components, the V(NiCo)-Se/NF achieves an outstanding specific capacity (1806.7 C g-1 at 1 A g-1), which is higher than that of V(NiCo)-O/NF (1208.3 C g-1) and V(NiCo)-S/NF (1558.4 C g-1). In addition, the capacity retention rate is 91.7 % (at 10 A g-1 after 10, 000 cycles). Utilizing V(NiCo)-Se/NF (positive) and activated carbon/NF (negative), the hybrid supercapacitor (HSC) achieves an impressive high energy density of 114.8 Wh kg-1 (at 679.5 W kg-1). Moreover, two HSCs in series can power the LED and stopwatch, and keep working for more than 60 min, displaying good practical application capabilities.

Carbon-Coated MOF-Derived Porous SnPS3 Core-Shell Structure as Superior Anode for Sodium-Ion Batteries

Metal thiophosphites have recently emerged as a hot electrode material system for sodium-ion batteries because of their large theoretical capacity. Nevertheless, the sluggish electrochemical reaction kinetics and drastic volume expansion induced by the low conductivity and inherent conversion-alloying reaction mechanism, require urgent resolution. Herein, a distinctive porous core-shell structure, denoted as SnPS3@C, is controllably synthesized by synchronously phosphor-sulfurizing resorcinol-formaldehyde-coated tin metal-organic framework cubes. Thanks to the 3D porous structure, the ion diffusion kinetics are accelerated. In addition, SnPS3@C features a tough protective carbon layer, which improves the electrochemical activity and reduces the polarization. As expected, the as-prepared SnPS3@C electrode exhibits superior electrochemical performance compared to pure SnPS3, including excellent rate capability (1342.4 and 731.1 mAh g-1 at 0.1 and 4 A g-1, respectively), and impressive long-term cycling stability (97.9% capacity retention after 1000 cycles at 1 A g-1). Moreover, the sodium storage mechanism is thoroughly studied by in-situ and ex-situ characterizations. This work offers an innovative approach to enhance the energy storage performance of metal thiophosphite materials through meticulous structural design, including the introduction of porous characteristics and core-shell structures.

Enhancing Rapid Li+/Na+ Storage Performance via Interface Engineering of Reduced Graphene Oxide-Wrapped Bimetallic Sulfide Nanocages

Transition-metal sulfide is considered to be an admirable transformational electrode material due to low cost, large specific capacity, and good reversibility in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Herein, the reduced graphene oxide-wrapped open bimetallic sulfide (NiS2-Co3S4@rGO) nanocage, derived from nickel-cobalt Prussian blue, was obtained by two-step calcination. There are luxuriant pore structures in the nanocage composite with a specific surface area of 85.28 m2 g-1, which provides plentiful paths for rapid transmission of Li+/Na+ and alleviates the volume stress caused by insertion and extraction of alkali metal ions. The excellent interface combination of bimetallic sulfide wrapped in reduced graphene oxide improves the conductivity and overall performance of the battery. Thanks to the special interface engineering, the open NiS2-Co3S4@rGO nanocage composite displays rapid lithium storage properties with an average diffusion coefficient of 8.5 × 10-13 cm2 s-1. Moreover, after 300 cycles, the reversible capacity of the composite is 1113.2 mAh g-1 at 1 A g-1. In SIBs, the capacity of the open NiS2-Co3S4@rGO composite is 487.9 mAh g-1 when the current density is 5 A g-1. These preeminent performances demonstrate the enormous development prospects of bimetallic sulfide nanocage as anode material in LIBs and SIBs.

2D Conductive Metal-Organic Frameworks Based on Tetraoxa[8]circulenes as Promising Cathode for Aqueous Zinc Ion Batteries

Aqueous zinc-ion batteries (ZIBs) are the new generation electrochemical energy storage systems. Recently, two-dimensional conductive metal-organic frameworks (2D c-MOFs) are attractive to serve as cathode materials of ZIBs due to their compositional diversity, abundant active sites, and excellent conductivity. Despite the growing interest in 2D c-MOFs, their application prospects are still to be explored. Herein, a tetraoxa[8]circulene (TOC) derivative with unique electronic structure and interesting redox-active property are synthesized to construct c-MOFs. A series of novel 2D c-MOFs (Cu-TOC, Zn-TOC and Mn-TOC) with different conductivities and packing modes are obtained by combining the linker tetraoxa[8]circulenes-2,3,5,6,8,9,11,12-octaol (8OH-TOC) and corresponding metal ions. Three c-MOFs all exhibit typical semiconducting properties, and Cu-TOC exhibits the highest electrical conductivity of 0.2 S cm-1 among them. Furthermore, their electrochemical performance as cathode materials for ZIBs have been investigated. They all performed high reversible capacity, decent cycle stability and excellent rate capability. This work reveals the key insights into the electrochemical application potential of 2D c-MOFs and advances their development as cathode materials in ZIBs.

In Situ Formation of Heterojunction in Composite Lithium Anode Facilitates Fast and Uniform Interfacial Ion Transport

Lithium metal is a highly promising anode for next-generation high-energy-density rechargeable batteries. Nevertheless, its practical application faces challenges due to the uncontrolled lithium dendrites growth and infinite volumetric expansion during repetitive cycling. Herein, a composite lithium anode is designed by mechanically rolling and pressing a cerium oxide-coated carbon textile with lithium foil (Li@CeO2/CT). The in situ generated cerium dioxide (CeO2) and cerium trioxide (Ce2O3) form a heterojunction with a reduced lithium-ion migration barrier, facilitating the rapid lithium ions migration. Additionally, both CeO2 and Ce2O3 exhibit higher adsorbed energy with lithium, enabling faster and more distributed interfacial transport of lithium ions. Furthermore, the high specific surface area of 3D skeleton can effectively reduce local current density, and alleviate the lithium volumetric changes upon plating/stripping. Benefiting from this unique structure, the highly compact and uniform lithium deposition is constructed, allowing the Li@CeO2/CT symmetric cells to maintain a stable cycling for over 500 cycles at an exceptional high current density of 100 mA cm-2. When paired with LiNi0.91Co0.06Mn0.03O2 (NCM91) cathode, the cell achieves 74.3% capacity retention after 800 cycles at 1 C, and a remarkable capacity retention of 81.1% after 500 cycles even at a high rate of 4  C.

From lab to field: Prussian blue frameworks as sustainable cathode materials

Prussian blue and Prussian blue analogues have attracted increasing attention as versatile framework materials with a wide range of applications in catalysis, energy conversion and storage, and biomedical and environmental fields. In terms of energy storage and conversion, Prussian blue-based materials have emerged as suitable candidates of growing interest for the fabrication of batteries and supercapacitors. Their outstanding electrochemical features such as fast charge-discharge rates, high capacity and prolonged cycling life make them favorable for energy storage application. Furthermore, Prussian blue and its analogues as rechargeable battery anodes can advance significantly by the precise control of their structure, morphology, and composition at the nanoscale. Their tunable structural and electronic properties enable the detection of many types of analytes with high sensitivity and specificity, and thus, they are ideal materials for the development of sensors for environmental detection, disease trend monitoring, and industrial safety. Additionally, Prussian blue-based catalysts display excellent photocatalytic performance for the degradation of pollutants and generation of hydrogen. Specifically, their excellent light capturing and charge separation capabilities make them stand out in photocatalytic processes, providing a sustainable option for environmental remediation and renewable energy production. Besides, Prussian blue coatings have been studied particularly for corrosion protection, forming stable and protective layers on metal surfaces, which extend the lifespan of infrastructural materials in harsh environments. Prussian blue and its analogues are highly valuable materials in healthcare fields such as imaging, drug delivery and theranostics because they are biocompatible and their further functionalization is possible. Overall, this review demonstrates that Prussian blue and related framework materials are versatile and capable of addressing many technical challenges in various fields ranging from power generation to healthcare and environmental management.

Sulfur-bridged bonds enabled structure modulation and space confinement of MnS for superior sodium-ion capacitors

Manganese sulfide (MnS) is a promising converion-type anode for sodium storage, owing to the virtues of high theoretical capacity, coupled with it crustal abundance and cost-effectiveness. Nevertheless, MnS suffers from inadequate electronic conductivity, sluggish Na+ reaction kinetics and considerable volume variation during discharge/charge process, thereby impeding its rate capability and capacity retention. Herein, a novel lamellar heterostructured composite of Fe-doped MnS nanoparticles/positively charged reduced graphene oxide (Fe-MnS/PG) was synthesized to overcome these issues. The Fe-doping can accelerate the ion/electron transfer, endowing fast electrochemical kinetics of MnS. Meanwhile, the graphene space confinement with strong MnSC bond interactions can facilite the interfacial electron transfer, hamper volume expansion and aggregation of MnS nanoparticles, stabilizing the structural integrity, thus improving the Na+ storage reversibility and cyclic stability. Combining the synergistic effect of Fe-doping and space confinement with strong MnSC bond interactions, the as-produced Fe-MnS/PG anode presents a remarkable capacity of 567 mAh/g at 0.1 A/g and outstanding rate performance (192 mAh/g at 10 A/g). Meanwhile, the as-assembled sodium-ion capacitor (SIC) can yield a high energy density of 119 Wh kg-1 and a maximum power density of 17500 W kg-1, with capacity retention of 77 % at 1 A/g after 5000 cycles. This work offers a promising strategy to develop MnS-based practical SICs with high energy and long lifespan, and paves the way for fabricating advanced anode materials.

Highly efficient nitrogen fixation over S-scheme heterojunction photocatalysts with enhanced active hydrogen supply

Photocatalytic N2 fixation is a promising strategy for ammonia (NH3) synthesis; however, it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2 adsorption/activation capability. Herein, an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2 fixation photocatalyst. The CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSx hollow dodecahedron. Within the heterojunction, the electronic interaction between ZnS and CoSx creates electron-deficient Zn sites with enhanced N2 chemisorption and electron-sufficient Co sites with active hydrogen supply for N2 hydrogenation, cooperatively reducing the energy barrier for N2 activation. In combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure, an excellent N2 fixation performance with a high NH3 yield of 1175.37 μmol g-1 h-1 is achieved. This study provides new insights into the design of heterojunction photocatalysts for N2 fixation.

Constructing Carbon Nanotube-Enhanced Ultra-Thin Organic Compounds with Multi-Redox Sites for "All-Temperature" Potassium-Ion Battery Anode and its Step-Wise K-Storage Mechanism

Organic compounds are regarded as important candidates for potassium-ion batteries (KIBs) due to their light elements, controllable polymerization, and tunable functional groups. However, intrinsic drawbacks largely restrict their application, including possible solubility in electrolytes, poor conductivity, and low diffusion coefficients. To address these issues, an ultrathin layered pyrazine/carbonyl-rich material (CT) is synthesized via an acid-catalyzed solvothermal reaction and homogeneously grown on carbon nanotubes (CNTs), marked as CT@CNT. Such materials have shown good features of exposing functional groups to guest ions and good electron transport paths, exhibiting high reversible capacity and remarkable rate capability over a wide temperature range. Two typical electrolytes are compared, demonstrating that the electrolyte of LX-146 is more suitable to maximize the electrochemical performances of electrodes at different temperatures. A stepwise reaction mechanism of K-chelating with C═O and C═N functional groups is proposed, verified by in/ex situ spectroscopic techniques and theoretical calculations, illustrating that pyrazines and carbonyls play the main roles in reacting with K+ cations, and CNTs promote conductivity and restrain electrode dissolution. This study provides new insights to understand the K-storage behaviors of organic compounds and their "all-temperature" application.

Well-Dispersed Bi nanoparticles for promoting the lithium storage performance of Si Anode: Effect of the bridging Bi nanoparticles

Silicon (Si) is considered a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity of up to 4200 mAh/g. However, the poor cycling and rate performances of Si induced by the low intrinsic electronic conductivity and large volume expansion during the lithiation/delithiation process limit its practical application. Herein, a novel silicon/bismuth@nitrogen-doped carbon (Si/Bi@NC) composite with nanovoids was synthesized and investigated as an advanced anode material for LIBs. In such a structure, ultrafine bismuth nanoparticles coupled with an N-doped carbon layer were introduced to modify the surface of Si nanoparticles. Subsequently, the lithiated LixBi has excellent high ionic conductivity and acts as a fast transport bridge for lithium ions. The introduced carbon coating layer and nanovoids can buffer the volume expansion of Si during the lithiation/delithiation process, thus maintaining structural stability during the cycling process. As a result, the Si/Bi@NC composite exhibits excellent electrochemical performance, providing a relatively high capacity of 955.8 mAh/g at 0.5 A/g after 450 cycles and excellent rate performance with a high capacity of 477.8 mAh/g even at 10.0 A/g. Furthermore, the assembled full cell with LiFePO4 as cathode and pre-lithium Si/Bi@NC as anode can provide a high capacity of 138.8 mAh/g at 1C after 90 cycles, exhibiting outstanding cycling performance.

A Review on Covalent Organic Frameworks as Artificial Interface Layers for Li and Zn Metal Anodes in Rechargeable Batteries

Li and Zn metals are considered promising negative electrode materials for the next generation of rechargeable metal batteries because of their non-toxicity and high theoretical capacity. However, the uneven deposition of metal ions (Li+ , Zn2+ ) and the uncontrolled growth of dendrites result in poor electrochemical stability, unsatisfactory cycle life, and rapid capacity decay of batteries assembled with Li and Zn electrodes. Owing to the unique internal directional channels and abundant redox active sites of covalent organic frameworks (COFs), they can be used to promote uniform deposition of metal ions during stripping/electroplating through interface modification strategies, thereby inhibiting dendrite growth. COFs provide a new perspective in addressing the challenges faced by the anodes of Li metal batteries and Zn ion batteries. This article discusses the stability and types of COFs, and summarizes some novel COF synthesis methods. Additionally, it reviews the latest progress and optimization methods of using COFs for metal anodes to improve battery performance. Finally, the main challenges faced in these areas are discussed. This review will inspire future research on metal anodes in rechargeable batteries.

Ni-Co-Mn complexed 3,4,9,10-perylenetetracarboxylic acid complexes as novel organic electrode materials for lithium-ion batteries

Ni-Co-Mn complexed 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA-NiCoMn) is prepared by hydrolysis of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and complexed reaction with Ni, Co and Mn ions. At the same time, graphene was added to PTCDA-NiCoMnin situ to obtain graphene in situ composited Ni-Co-Mn complexed 3,4,9,10-perylenetetracarboxylic dianhydride composites (PTCDA-NiCoMn-G). The prepared PTCDA-NiCoMn composite exhibited a fibrous structure, and the number of pore units increased with the expansion of the fibrous structure. After the in situ recombination of graphene, shorter PTCDA-NiCoMn tubular fibers were dispersed between the thin layers of graphene, showing a larger surface area with more PTCDA-NiCoMn active components exposed, which is conducive to better electrochemical properties. As a result, the initial charge/discharge capacities of PTCDA-NiCoMn and PTCDA-NiCoMn-G electrodes are 1972.9 and 1806.6 mA h g-1 with initial coulombic efficiencies of 56.3% and 62.52%, respectively, at 100 mA g-1. After 200 cycles, the charge/discharge capacities of PTCDA-NiCoMn and PTCDA-NiCoMn-G are 617.0 and 876.4 mA h g-1 with capacity retention ratios of 51.4% and 73.0% at 100 mA g-1, respectively. Similarly, PTCA-NiCoMn-G electrodes show higher capacities than the PTCA-NiCoMn electrode at different current densities of 0.1, 0.2, 0.5, 1.0, 2.0 and 5 A g-1. The results show that PTCDA-NiCoMn-G electrode displays superior capacity, ICE, cycle and rate behaviors. The complexation of NiCoMn reduces the solubility of the PTCDA active units in the electrolyte, and the in situ recombination of graphene increases the dispersion of the active components, exposes more active sites, and effectively improves the conductive performance, which contributes to the electrochemical properties of the PTCDA-NiCoMn-G electrode.

In-situ-grown multidimensional Cu-doped Co1-xS2@MoS2 on N-doped carbon nanofibers as anode materials for high-performance alkali metal ion batteries

Transition metal sulfides with the high theoretical capacity and low cost have been considered as advanced anode candidate for alkali metal ion batteries, but suffered from unsatisfactory electrical conductivity and huge volume expansion. Herein, a multidimensional structure Cu-doped Co1-xS2@MoS2 in-situ-grown on N-doped carbon nanofibers (denoted as Cu-Co1-xS2@MoS2 NCNFs) have been elaborately constructed for the first time. The bimetallic zeolitic imidazolate framework CuCo-ZIFs were encapsulated in the one-dimensional (1D) NCNFs through an electrospinning route and then on which the two-dimensional (2D) MoS2 nanosheets were in-situ grown via a hydrothermal process. The architecture of 1D NCNFs can effectively shorten ion diffusion path and enhance electrical conductivity. Besides, the formed heterointerface between MOF-derived binary metal sulfides and MoS2 can provide extra active centers and accelerate reaction kinetics, which guarantee a superior reversibility. As expected, the resulting Cu-Co1-xS2@MoS2 NCNFs electrode delivers excellent specific capacity of Na-ion batteries (845.6 mAh/g at 0.1 A/g), Li-ion batteries (1145.7 mAh/g at 0.1 A/g), and K-ion batteries (474.3 mAh/g at 0.1 A/g). Therefore, this innovative design strategy will bring a meaningful prospect for developing high-performance multi-component metal sulfides electrode for alkali metal ion batteries.

Biomass-Derived Flexible Carbon Architectures as Self-Supporting Electrodes for Energy Storage

With the swift advancement of the wearable electronic devices industry, the energy storage components of these devices must possess the capability to maintain stable mechanical and chemical properties after undergoing multiple bending or tensile deformations. This circumstance has expedited research efforts toward novel electrode materials for flexible energy storage devices. Nonetheless, among the numerous materials investigated to date, the incorporation of metal current collectors or insulative adhesives remains requisite, which entails additional costs, unnecessary weight, and high contact resistance. At present, biomass-derived flexible architectures stand out as a promising choice in electrochemical energy device applications. Flexible self-supporting properties impart a heightened mechanical performance, obviating the need for additional binders and lowering the contact resistance. Renewable, earth-abundant biomass endows these materials with cost-effectiveness, diversity, and modulable chemical properties. To fully exploit the application potential in biomass-derived flexible carbon architectures, understanding the latest advancements and the comprehensive foundation behind their synthesis assumes significance. This review delves into the comprehensive analysis of biomass feedstocks and methods employed in the synthesis of flexible self-supporting carbon electrodes. Subsequently, the advancements in their application in energy storage devices are elucidated. Finally, an outlook on the potential of flexible carbon architectures and the challenges they face is provided.

Breaking Barriers: Binder-Assisted NiS/NiS2 Heterostructure Anode with High Initial Coulombic Efficiency for Advanced Sodium-Ion Batteries

Developing sodium-ion batteries (SIBs) with high initial coulombic efficiency (ICE) and long-term cycling stability is crucial to meet energy storage device requirements. Designing anode materials that could exhibit high ICE is a promising strategy to realize enhanced energy density in SIBs. A trifunctional network binder substantially improves the electrochemical performance and ICE, providing excellent mechanical properties and strong adhesion strength. A rationally designed electrode material and binder can achieve high ICE, long cycling performance, and excellent specific capacity. Here, a NiS/NiS2 heterostructure as an anode material and a trifunctional network binder (SA-g-PAM) are designed for SIBs. Unprecedently, the anode comprising of an SA-g-PAM binder achieved the highest ICE of 90.7% and remarkable cycling stability for 19000 cycles at a current density of 10 A g-1 and maintained the specific capacity of 482.3 mAh g-1 even after 19000 cycles. This exciting work provides an alternate direction to the battery industry for developing high-performance electrode materials and binders with high ICE and excellent cycling stability for energy storage devices.

Densified graphene-like carbon nanosheets with enriched heteroatoms enabling superior gravimetric and volumetric potassium storage capacities

Constructing carbon electrodes with abundant heteroatoms and appropriate graphitic interlayer spacing remains a major challenge for achieving high gravimetric and volumetric potassium storage capacities with fast kinetics. Herein, we constructed 3D graphene-like N, F dual-doped carbon sheets induced by Ni template (N, F-CNS-Ni) with dense structure and rich active sites, providing a promising approach to address the facing obstacles. Highly reversible K-ion insertion/extraction is realized in the graphitic carbon structure, and K-adsorption capability is enhanced by introducing N/F heteroatoms. As a result, the N, F-CNS-Ni electrode exhibits ultrahigh gravimetric and volumetric capacities of 404.5 mA h g^-1 and 281.3 mA h cm^-3 at 0.05 A/g, respectively, and a superb capacity of 259.3 mA h g^-1 with a capacity retention ratio of 90 % even after 600 cycles at 5 A/g. This work presents a simple Ni-based template method to prepare graphene-like carbon nanosheets with high packing density and rich heteroatoms, and offers mechanism insight for achieving superior K-ion storage.

High-Capacity Sb/Fe2S3 Sodium-Ion Battery Anodes Fabricated by a One-Step Redox Reaction, Followed by Ball Milling with Graphite

Antimony (Sb) has been considered a promising anode for sodium-ion batteries (SIBs) owing to its high theoretical capacity (660 mA h g^-1) and low redox voltage (0.2-0.9 V vs Na⁺/Na). However, the capacity degradation caused by the volumetric variation during battery discharge/charge hinders the practical application. Herein, guided by the DFT calculation, Sb/Fe₂S₃ was fabricated by annealing Fe and Sb₂S₃ mixed powder. Next, Sb/Fe₂S₃ was blended with 15 wt % graphite by ball milling, yielding nano-Sb/Fe₂S₃ anchored on an exfoliated graphite composite (denoted as Sb/Fe₂S₃-15%). When applied as an anode of SIBs, Sb/Fe₂S₃-15% delivered reversible capacities of 565, 542, 467, 366, 285, and 236 mA h g^-1 at current rates of 1, 2, 4, 6, 8, and 10 A g^-1, respectively, surpassing most of the Sb-based anodes. The co-existence of highly conductive Fe₂S₃ and Sb minimizes the polarization of the anode. Our experiments proved that the Sb and Fe₂S₃ phases were reversible during discharge/charge cycling, and the exfoliated graphite can accelerate the Na⁺ diffusion and e^- conduction. The proposed synthesis method of this work can also be applicable to synthesize various antimony/transition metal sulfide heterostructures (Sb/M_1-xS), which may be applied in a series of fields.

Nickel sulfide/nickel phosphide heterostructures anchored on porous carbon nanosheets with rapid electron/ion transport dynamics for sodium-ion half/full batteries

Nickel-based materials have been extensively deemed as promising anodes for sodium-ion batteries (SIBs) owing to their superior capacity. Unfortunately, the rational design of electrodes as well as long-term cycling performance remains a thorny challenge due to the huge irreversible volume change during the charge/discharge process. Herein, the heterostructured ultrafine nickel sulfide/nickel phosphide (NiS/Ni₂P) nanoparticles closely attached to the interconnected porous carbon sheets (NiS/Ni₂P@C) are designed by facile hydrothermal and annealing methods. The NiS/Ni₂P heterostructure promotes ion/electron transport, thus accelerating the electrochemical reaction kinetics benefited from the built-in electric field effect. Moreover, the interconnected porous carbon sheets offer rapid electron migration and excellent electronic conductivity, while releasing the volume variance during Na⁺ intercalation and deintercalation, guaranteeing superior structural stability. As expected, the NiS/Ni₂P@C electrode exhibits a high reversible specific capacity of 344 mAh g^-1 at 0.1 A g^-1 and great rate stability. Significantly, the implementation of NiS/Ni₂P@C//Na₃(VPO₄)₂F₃ SIB full cell configuration exhibits relatively satisfactory cycle performance, which suggests its widely practical application. This research will develop an effective method for constructing heterostructured hybrids for electrochemical energy storage.

Facet Engineering of Advanced Electrocatalysts Toward Hydrogen/Oxygen Evolution Reactions

The crystal facets featured with facet-dependent physical and chemical properties can exhibit varied electrocatalytic activity toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) attributed to their anisotropy. The highly active exposed crystal facets enable increased mass activity of active sites, lower reaction energy barriers, and enhanced catalytic reaction rates for HER and OER. The formation mechanism and control strategy of the crystal facet, significant contributions as well as challenges and perspectives of facet-engineered catalysts for HER and OER are provided.

The electrocatalytic water splitting technology can generate high-purity hydrogen without emitting carbon dioxide, which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality. Electrocatalysts can effectively reduce the reaction energy barrier and increase the reaction efficiency. Facet engineering is considered as a promising strategy in controlling the ratio of desired crystal planes on the surface. Owing to the anisotropy, crystal planes with different orientations usually feature facet-dependent physical and chemical properties, leading to differences in the adsorption energies of oxygen or hydrogen intermediates, and thus exhibit varied electrocatalytic activity toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this review, a brief introduction of the basic concepts, fundamental understanding of the reaction mechanisms as well as key evaluating parameters for both HER and OER are provided. The formation mechanisms of the crystal facets are comprehensively overviewed aiming to give scientific theory guides to realize dominant crystal planes. Subsequently, three strategies of selective capping agent, selective etching agent, and coordination modulation to tune crystal planes are comprehensively summarized. Then, we present an overview of significant contributions of facet-engineered catalysts toward HER, OER, and overall water splitting. In particular, we highlight that density functional theory calculations play an indispensable role in unveiling the structure–activity correlation between the crystal plane and catalytic activity. Finally, the remaining challenges in facet-engineered catalysts for HER and OER are provided and future prospects for designing advanced facet-engineered electrocatalysts are discussed.