Robust SnO2-x Nanoparticle-Impregnated Carbon Nanofibers with Outstanding Electrochemical Performance for Advanced Sodium-Ion Batteries

Tailoring Stress-Relieved Structure for SnSe Toward High Performance Potassium Ion Batteries

Metal chalcogenides as an ideal family of anode materials demonstrate a high theoretical specific capacity for potassium ion batteries (PIBs), but the huge volume variance and poor cyclic stability hinder their practical applications. In this study, a design of a stress self-adaptive structure with ultrafine SnSe nanoparticles embedded in carbon nanofiber (SnSe@CNF) via the electrospinning technology is presented. Such an architecture delivers a record high specific capacity (272 mAh g-1 at 50 mA g-1) and high-rate performance (125 mAh g-1 at 1 A g-1) as a PIB anode. It is decoded that the fundamental understanding for this great performance is that the ultrafine SnSe particles enhance the full utilization of the active material and achieve stress relief as the stored strain energy from cycling is insufficient to drive crack propagation and thus alleviates the intrinsic chemo-mechanical degradation of metal chalcogenides.

Amorphous Fe2O3 Anchored on N-Doped Graphene with Internal Micro-Channels as an Active and Durable Anode for Sodium-Ion Batteries

The reduced graphene oxide (rGO) exhibits outstanding electrical conductivity and a high specific surface area, making it a promising material for various applications. Fe2O3 is highly desirable due to its significant theoretical capacity and cost-effectiveness, high abundance, and environmental friendliness. However, the performance of these r-GO/Fe2O3 composite electrodes still needs to be further improved, especially in terms of cycle stability. The composite of Fe2O3 anchored on N-doped graphene with inside micro-channels (Fe2O3@N-GIMC) was used to be efficiently prepared. Because the inside channels can furnish extra transmission pathways and absorption websites and the interconnected structure can efficaciously forestall pulverization and aggregation of electrode materials. In addition, N doping is also beneficial to improve its electrochemical performance. Thus, it demonstrates exceptional sodium storage characteristics, including notable electrochemical activity, impressive initial Coulombic efficiency, and favorable rate performance. The optimized Fe2O3@N-GIMC indicates outstanding discharge capacity (573.5 mAh g-1 at 1 A g-1), significant rate performance (333.6 mAh g-1 at 8 A g-1), and stable long-term cycle durability (308.9 mAh g-1 after 1000 cycles at 1 A g-1, 200.8 mAh g-1 after 4000 cycles at 1 A g-1) as a sodium-ion battery anode. This presents a new approach for preparing graphene-based high-functional composites and lays a stable basis for further expanding its application field.

SnO2/SnS heterojunction anchoring on CMK-3 mesoporous network improves the reversibility of conversion reaction for lithium/sodium ions storage

Tin oxide-based (SnO2) materials show high theoretical capacity for lithium and sodium storage benefiting from a double-reaction mechanism of conversion and alloying reactions. However, due to the limitation of the reaction thermodynamics and kinetics, the conversion reaction process of SnO2usually shows irreversibility, resulting in serious capacity decay and hindering the further application of the SnO2anode. Herein, SnO2/SnS heterojunction was anchored on the surface and inside of CMK-3 byinsitusynthesis method, forming a stable 3D structural material (SnO2/SnS@CMK-3). The electrochemical properties of SnO2/SnS@CMK-3 composite show high capacity and reversible conversion reaction, which was attributed to the synergistic effect of CMK-3 and SnO2/SnS heterojunction. To further investigate the influence of the heterojunction on the reversibility of the conversion reaction, the Gibbs free energy (ΔG) was calculated using density functional theory. The results show that SnO2/SnS heterojunction has a closer to zero ΔGfor lithium/sodium ion batteries compared to SnO2, indicating that the heterojunction enhances the reversibility of the conversion reaction in chemical reaction thermodynamics. Our work provides insights into the reversibility of the conversion reaction of SnO2-based materials, which is essential for improving their electrochemical performance.

Optimising Hollow-Structured Silicon Nanoparticles for Lithium-Ion Batteries

Silicon has been proven to be one of the most promising anode materials for the next generation of lithium-ion batteries for application in batteries, the Si anode should have high capacity and must be industrially scalable. In this study, we designed and synthesised a hollow structure to meet these requirements. All the processes were carried out without special equipment. The Si nanoparticles that are commercially available were used as the core sealed inside a TiO2 shell, with rationally designed void space between the particles and shell. The Si@TiO2 were characterised using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The optimised hollow-structured silicon nanoparticles, when used as the anode in a lithium-ion battery, exhibited a high reversible specific capacity over 630 mAhg-1, much higher than the 370 mAhg-1 from the commercial graphite anodes. This excellent electrochemical property of the nanoparticles could be attributed to their optimised phase and unique hollow nanostructure.

Compact TiO2@SnO2@C heterostructured particles as anode materials for sodium-ion batteries with improved volumetric capacity

Sodium-ion batteries (SIBs) are promising candidates for large-scale energy storage. Increasing the energy density of SIBs demands anode materials with high gravimetric and volumetric capacity. To overcome the drawback of low density of conventional nanosized or porous electrode materials, compact heterostructured particles are developed in this work with improved Na storage capacity by volume, which are composed of SnO₂ nanoparticles loaded into nanoporous TiO₂ followed by carbon coating. The resulted TiO₂@SnO₂@C (denoted as TSC) particles inherit the structural integrity of TiO₂ and extra capacity contribution from SnO₂, delivering a volumetric capacity of 393 mAh cm^-3 notably higher than that of porous TiO₂ and commercial hard carbon. The heterogeneous interface between TiO₂ and SnO₂ is believed to promote the charge transfer and facilitate the redox reactions in the compact heterogeneous particles. This work demonstrates a useful strategy for electrode materials with high volumetric capacity.

Enlarged Interlayer Spacing of Marigold-Shaped 1T-MoS2 with Sulfur Vacancies via Oxygen-Assisted Phosphorus Embedding for Rechargeable Zinc-Ion Batteries

Structural unsteadiness and sluggish diffusion of divalent zinc cations in cathodes during cycling severely limit further applications of MoS₂ for rechargeable aqueous zinc-ion batteries (ZIBs). To circumvent these hurdles, herein, phosphorus (P) atom embedded three-dimensional marigold-shaped 1T MoS₂ structures combined with the design of S vacancies (Sv) are synthesized via the oxygen-assisted solvent heat method. The oxygen-assisted method is utilized to aid the P-embedding into the MoS₂ crystal, which can expand the interlayer spacing of P-MoS₂ and strengthen Zn²⁺ intercalation/deintercalation. Meanwhile, the three-dimensional marigold-shaped structure with 1T phase retains the internal free space, can adapt to the volume change during charge and discharge, and improve the overall conductivity. Moreover, Sv is not only conducive to the formation of rich active sites to diffuse electrons and Zn²⁺ but also improves the storage capacity of Zn²⁺. The electrochemical results show that P-MoS₂ can reach a high specific capacity of 249 mAh g^-1 at 0.1 A g^-1. The capacity remains at 102 mAh g^-1 after 3260 cycles at a current of 0.5 A g^-1, showing excellent electrochemical performance for Zn²⁺ ion storage. This research provides a more efficient method of P atom embedded MoS₂-based electrodes and will heighten our comprehension of developing cathodes for the ZIBs.

2D Organic Materials: Status and Challenges

In the past few decades, 2D layer materials have gradually become a central focus in materials science owing to their uniquely layered structural qualities and good optoelectronic properties. However, in the development of 2D materials, several disadvantages, such as limited types of materials and the inability to synthesize large-scale materials, severely confine their application. Therefore, further exploration of new materials and preparation methods is necessary to meet technological developmental needs. Organic molecular materials have the advantage of being customizable. Therefore, if organic molecular and 2D materials are combined, the resulting 2D organic materials would have excellent optical and electrical properties. In addition, through this combination, the free design and large-scale synthesis of 2D materials can be realized in principle. Furthermore, 2D organic materials exhibit excellent properties and unique functionalities along with great potential for developing sensors, biomedicine, and electronics. In this review, 2D organic materials are divided into five categories. The preparation methods and material properties of each class of materials are also described in detail. Notably, to comprehensively understand each material's advantages, the latest research applications for each material are presented in detail and summarized. Finally, the future development and application prospects of 2D organic materials are briefly discussed.

Yolk-Shell Sb@Void@Graphdiyne Nanoboxes for High-Rate and Long Cycle Life Sodium-Ion Batteries

Antimony (Sb) has been pursued as a promising anode material for sodium-ion batteries (SIBs). However, it suffers from severe volume expansion during the sodiation-desodiation process. Encapsulating Sb into a carbon matrix can effectively buffer the volume change of Sb. However, the sluggish Na⁺ diffusion kinetics in traditional carbon shells is still a bottleneck for achieving high-rate performance in Sb/C composite materials. Here we design and synthesize a yolk-shell Sb@Void@graphdiyne (GDY) nanobox (Sb@Void@GDY NB) anode for high-rate and long cycle life SIBs. The intrinsic in-plane cavities in GDY shells offer three-dimensional Na⁺ transporting channels, enabling fast Na⁺ diffusion through the GDY shells. Electrochemical kinetics analyses show that the Sb@Void@GDY NBs exhibit faster Na⁺ transport kinetics than traditional Sb@C NBs. In situ transmission electron microscopy analysis reveals that the hollow structure and the void space between Sb and GDY successfully accommodate the volume change of Sb during cycling, and the plastic GDY shell maintains the structural integrity of NBs. Benefiting from the above structural merits, the Sb@Void@GDY NBs exhibit excellent rate capability and extraordinary cycling stability.

Recent Advances on Heterojunction-Type Anode Materials for Lithium-/Sodium-Ion Batteries

Rechargeable batteries are key in the field of electrochemical energy storage, and the development of advanced electrode materials is essential to meet the increasing demand of electrochemical energy storage devices with higher density of energy and power. Anode materials are the key components of batteries. However, the anode materials still suffer from several challenges such as low rate capability and poor cycling stability, limiting the development of high-energy and high-power batteries. In recent years, heterojunctions have received increasing attention from researchers as an emerging material, because the constructed heterostructures can significantly improve the rate capability and cycling stability of the materials. Although many research progress has been made in this field, it still lacks review articles that summarize this field in detail. Herein, this review presents the recent research progress of heterojunction-type anode materials, focusing on the application of various types of heterojunctions in lithium/sodium-ion batteries. Finally, the heterojunctions introduced in this review are summarized, and their future development is anticipated.

Nanocomposite hydrogels for biomedical applications

Nanomaterials' unique structures at the nanometer level determine their incredible functions, and based on this, they can be widely used in the field of nanomedicine. However, nanomaterials do possess disadvantages that cannot be ignored, such as burst release, rapid elimination, and poor bioadhesion. Hydrogels are scaffolds with three‐dimensional structures, and they exhibit good biocompatibility and drug release capacity. Hydrogels are also associated with disadvantages for biomedical applications such as poor anti‐tumor capability, weak bioimaging capability, limited responsiveness, and so on. Incorporating nanomaterials into the 3D hydrogel network through physical or chemical covalent action may be an effective method to avoid their disadvantages. In nanocomposite hydrogel systems, multifunctional nanomaterials often work as the function core, giving the hydrogels a variety of properties (such as photo‐thermal conversion, magnetothermal conversion, conductivity, targeting tumor, etc.). While, hydrogels can effectively improve the retention effect of nanomaterials and make the nanoparticles have good plasticity to adapt to various biomedical applications (such as various biosensors). Nanocomposite hydrogel systems have broad application prospects in biomedicine. In this review, we comprehensively summarize and discuss the most recent advances of nanomaterials composite hydrogels in biomedicine, including drug and cell delivery, cancer treatment, tissue regeneration, biosensing, and bioimaging, and we also briefly discussed the current situation of their commoditization in biomedicine.

Laser-Derived Interfacial Confinement Enables Planar Growth of 2D SnS2 on Graphene for High-Flux Electron/Ion Bridging in Sodium Storage

Establishing covalent heterointerfaces with face-to-face contact is promising for advanced energy storage, while challenge remains on how to inhibit the anisotropic growth of nucleated crystals on the matrix. Herein, face-to-face covalent bridging in-between the 2D-nanosheets/graphene heterostructure is constructed by intentionally prebonding of laser-manufactured amorphous and metastable nanoparticles on graphene, where the amorphous nanoparticles were designed via the competitive oxidation of Sn-O and Sn-S bonds, and metastable feature was employed to facilitate the formation of the C-S-Sn covalent bonding in-between the heterostructure. The face-to-face bridging of ultrathin SnS₂ nanosheets on graphene enables the heterostructure huge covalent coupling area and high loading and thus renders unimpeded electron/ion transfer pathways and indestructible electrode structure, and impressive reversible capacity and rate capability for sodium-ion batteries, which rank among the top in records of the SnS₂-based anodes. Present work thus provides an alternative of constructing heterostructures with planar interfaces for electrochemical energy storage and even beyond.

Bamboo Weaving Inspired Design of a Carbonaceous Electrode with Exceptionally High Volumetric Capacity

A highly densified electrode material is desirable to achieve large volumetric capacity. However, pores acting as ion transport channels are critical for high utilization of active material. Achieving a balance between high volume density and pore utilization remains a challenge particularly for hollow materials. Herein, capillary force is employed to convert hollow fibers to a bamboo-weaving-like flexible electrode (BWFE), in which the shrinkage of hollow space results in high compactness of the electrode. The volume of the electrode can be decreased by 96% without sacrificing the gravimetric capacity. Importantly, the conductivity of BWFE after thermal treatment can reach up to 50,500 S/m which exceeds that for most other carbon materials. Detailed mechanical analysis reveals that, due to the strong interaction between nanoribbons, Young's modulus of the electrode increases by 105 times. After SnO₂ active materials is impregnated, the BWFE/SnO₂ electrode exhibits an exceptionally ultrahigh volumetric capacity of 2000 mAh/cm³.

Tin-Based Anode Materials for Stable Sodium Storage: Progress and Perspective

Because of concerns regarding shortages of lithium resources and the urgent need to develop low-cost and high-efficiency energy-storage systems, research and applications of sodium-ion batteries (SIBs) have re-emerged in recent years. Herein, recent advances in high-capacity Sn-based anode materials for stable SIBs are highlighted, including tin (Sn) alloys, Sn oxides, Sn sulfides, Sn selenides, Sn phosphides, and their composites. The reaction mechanisms between Sn-based materials and sodium are clarified. Multiphase and multiscale structural optimizations of Sn-based materials to achieve good sodium-storage performance are emphasized. Full-cell designs using Sn-based materials as anodes and further development of Sn-based materials are discussed from a commercialization perspective. Insights into the preparation of future high-performance Sn-based anode materials and the construction of sodium-ion full batteries with a high energy density and long service life are provided.

Heterogeneous interface-induced electrocatalytic efficiency boosting of bimetallic Cu/Zn selenides for stable water oxidation and oxygen reduction reactions

Low overpotential and high stability of heterostructured bimetallic copper and zinc selenides for OER and ORR.

Organic/Inorganic Hybrid Fibers: Controllable Architectures for Electrochemical Energy Applications

Organic/inorganic hybrid fibers (OIHFs) are intriguing materials, possessing an intrinsic high specific surface area and flexibility coupled to unique anisotropic properties, diverse chemical compositions, and controllable hybrid architectures. During the last decade, advanced OIHFs with exceptional properties for electrochemical energy applications, including possessing interconnected networks, abundant active sites, and short ion diffusion length have emerged. Here, a comprehensive overview of the controllable architectures and electrochemical energy applications of OIHFs is presented. After a brief introduction, the controllable construction of OIHFs is described in detail through precise tailoring of the overall, interior, and interface structures. Additionally, several important electrochemical energy applications including rechargeable batteries (lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries), supercapacitors (sandwich-shaped supercapacitors and fiber-shaped supercapacitors), and electrocatalysts (oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction) are presented. The current state of the field and challenges are discussed, and a vision of the future directions to exploit OIHFs for electrochemical energy devices is provided.

Harnessing the Volume Expansion of MoS3 Anode by Structure Engineering to Achieve High Performance Beyond Lithium-Based Rechargeable Batteries

Beyond-lithium-ion storage devices are promising alternatives to lithium-ion storage devices for low-cost and large-scale applications. Nowadays, the most of high-capacity electrodes are crystal materials. However, these crystal materials with intrinsic anisotropy feature generally suffer from lattice strain and structure pulverization during the electrochemical process. Herein, a 2D heterostructure of amorphous molybdenum sulfide (MoS₃ ) on reduced graphene surface (denoted as MoS₃ -on-rGO), which exhibits low strain and fast reaction kinetics for beyond-lithium-ions (Na⁺ , K⁺ , Zn²⁺ ) storage is demonstrated. Benefiting from the low volume expansion and small sodiation strain of the MoS₃ -on-rGO, it displays ultralong cycling performance of 40 000 cycles at 10 A g^-1 for sodium-ion batteries. Furthermore, the as-constructed 2D heterostructure also delivers superior electrochemical performance when used in Na⁺ full batteries, solid-state sodium batteries, K⁺ batteries, Zn²⁺ batteries and hybrid supercapacitors, demonstrating its excellent application prospect.

Conversion-Alloying Anode Materials for Sodium Ion Batteries

The past decade has witnessed a rapidly growing interest toward sodium ion battery (SIB) for large-scale energy storage in view of the abundance and easy accessibility of sodium resources. Key to addressing the remaining challenges and setbacks and to translate lab science into commercializable products is the development of high-performance anode materials. Anode materials featuring combined conversion and alloying mechanisms are one of the most attractive candidates, due to their high theoretical capacities and relatively low working voltages. The current understanding of sodium-storage mechanisms in conversion-alloying anode materials is presented here. The challenges faced by these materials in SIBs, and the corresponding improvement strategies, are comprehensively discussed in correlation with the resulting electrochemical behavior. Finally, with the guidance and perspectives, a roadmap toward the development of advanced conversion-alloying materials for commercializable SIBs is created.

Synergistic Engineering of Defects and Heterostructures Enhance Lithium/Sodium Storage Properties of F-SnO2-x -SnS2-x Nanocrystals Supported on N,S-Graphene

Phase engineering of the electrode materials in terms of designing heterostructures, introducing heteroatom and defects, improves great prospects in accelerating the charge storage kinetics during the repeated Li⁺ /Na⁺ insertion/deintercalation. Herein, a new design of Li/Na-ion battery anodes through phase regulating is reported consisting of F-doped SnO₂ -SnS₂ heterostructure nanocrystals with oxygen/sulfur vacancies (V_O /V_S ) anchored on a 2D sulfur/nitrogen-doped reduced graphene oxide matrix (F-SnO_2-x -SnS_2-x @N/S-RGO). Consequently, the F-SnO_2-x -SnS_2-x @N/S-RGO anode demonstrates superb high reversible capacity and long-term cycling stability. Moreover, it exhibits excellent great rate capability with 589 mAh g^-1 for Li⁺ and 296 mAh g^-1 at 5 A g^-1 for Na⁺ . The enhanced Li/Na storage properties of the nanocomposites are not only attributed to the increase in conductivity caused by V_O /V_S and F doping (confirmed by DFT calculations) to accelerate their charge-transfer kinetics but also the increased interaction between F-SnO_2-x -SnS_2-x and Li/Na through heterostructure. Meanwhile, the hierarchical F-SnO_2-x -SnS_2-x @N/S-RGO network structure enables fast infiltration of electrolyte and improves electron/ion transportation in the electrode, and the corrosion resistance of F doping contributes to prolonged cycle stability.

Electrochemically Engineering Antimony Interspersed on Graphene toward Advanced Sodium-Storage Anodes

Nanoengineering of metal anode materials shows great potential for energy storage with high capacity. Zero-dimensional nanoparticles are conducive to acquire remarkable electrochemical properties in sodium-ion batteries (SIBs) because of their enlarged surface active sites. However, it is still difficult to fulfill the requirements of practical applications in batteries owing to the deficiency of efficient and scalable preparation approaches of high-performance metal electrode materials. Herein, an electrochemical cathodic corrosion method is proposed for the tunable preparation of nanostructured antimony (Sb) by the introduction of a surfactant, which can efficiently avoid the agglomeration of Sb atom clusters generated from the Zintl compound and further stacking into bulk during the electrochemical process. Subsequently, graphene as the support and conductive matrix is uniformly interspersed by generating Sb nanoparticles (Sb/Gr). Moreover, the reversible crystalline-phase evolution of Sb ⇋ NaSb ⇋Na₃Sb for Sb/Gr was studied by in situ X-ray diffraction (XRD). Benefiting from the interconnection of the conductive network, Sb/Gr anodes deliver a high capacity of 635.34 mAh g^-1, a retained capacity of 507.2 mAh g^-1 after 150 cycles at 0.1 C (1 C = 660 mAh g^-1), and excellent rate performance with the capacities of 473.41 and 405.09 mAh g^-1 at 2 and 5 C, respectively. The superior cycle stability with a capacity of 346.26 mAh g^-1 is achieved after 500 cycles at 2 C. This electrochemical approach offers a new route toward developing metal anodes with designed nanostructures for high-performance SIBs.

2D III-Nitride Materials: Properties, Growth, and Applications

2D III-nitride materials have been receiving considerable attention recently due to their excellent physicochemical properties, such as high stability, wide and tunable bandgap, and magnetism. Therefore, 2D III-nitride materials can be applied in various fields, such as electronic and photoelectric devices, spin-based devices, and gas detectors. Although the developments of 2D h-BN materials have been successful, the fabrication of other 2D III-nitride materials, such as 2D h-AlN, h-GaN, and h-InN, are still far from satisfactory, which limits the practical applications of these materials. In this review, recent advances in the properties, growth methods, and potential applications of 2D III-nitride materials are summarized. The properties of the 2D III-nitride materials are mainly obtained by first-principles calculations because of the difficulties in the growth and characterizations of these materials. The discussion on the growth of 2D III-nitride materials is focused on 2D h-BN and h-AlN, as the developments of 2D h-GaN and h-InN are yet to be realized. Therefore, applications have been realized mostly based on the 2D h-BN materials; however, many potential applications are cited for the entire range of 2D III-nitride materials. Finally, future research directions and prospects in this field are also discussed.

Oxygen Vacancies Boosting Lithium-Ion Diffusion Kinetics of Lithium Germanate for High-Performance Lithium Storage

Oxygen vacancies play a positive role in optimizing the physical and chemical properties of metal oxides. In this work, we demonstrated oxygen vacancy-promoted enhancement of Li-ion diffusion kinetics in Li₂GeO₃ nanoparticle-encapsulated carbon nanofibers (denoted as Li₂GeO_3-x/C) and accordingly boosted lithium storage. The introduction of the oxygen vacancies in Li₂GeO_3-x/C can enhance electronic conductivity and evidently decrease activation energy of Li-ion transport, thus resulting in evidently accelerated Li-ion diffusion kinetics during the lithiation/delithiation process. Thus, the Li₂GeO_3-x/C nanofibers exhibit an exceptionally large discharge capacity of 1460.5 mA h g^-1 at 0.1 A g^-1, high initial Coulombic efficiency of 81.3%, and excellent rate capability. This facile and efficient strategy could provide a reference for injecting the oxygen vacancies into other metal oxides for high-performance anode materials.

Photodynamic immunotherapy of cancers based on nanotechnology: recent advances and future challenges

Photodynamic therapy (PDT) is a non-invasive or minimally-invasive treatment which applies photosensitizers (PSs) to create reactive oxygen species (ROS) exposed to light trigger to destroy cancer cells. PDT can activate host anti-tumor immune responses but not powerful enough to kill metastatic tumors. Because of its carrier advantage, imaging, and therapeutic function together with enhanced permeability and retention (EPR) effect, nano-materials have already been used in photo-immunotherapy. Herein, photodynamic immunotherapy (PDIT) based on nanotechnology seems to be a hopeful new form of cancer therapy. In this article, we firstly summarize the recent development in photodynamic immunotherapy based on nanotechnology.

Recent Advances in Silicon-Based Electrodes: From Fundamental Research toward Practical Applications

The increasing demand for higher-energy-density batteries driven by advancements in electric vehicles, hybrid electric vehicles, and portable electronic devices necessitates the development of alternative anode materials with a specific capacity beyond that of traditional graphite anodes. Here, the state-of-the-art developments made in the rational design of Si-based electrodes and their progression toward practical application are presented. First, a comprehensive overview of fundamental electrochemistry and selected critical challenges is given, including their large volume expansion, unstable solid electrolyte interface (SEI) growth, low initial Coulombic efficiency, low areal capacity, and safety issues. Second, the principles of potential solutions including nanoarchitectured construction, surface/interface engineering, novel binder and electrolyte design, and designing the whole electrode for stability are discussed in detail. Third, applications for Si-based anodes beyond LIBs are highlighted, specifically noting their promise in configurations of Li-S batteries and all-solid-state batteries. Fourth, the electrochemical reaction process, structural evolution, and degradation mechanisms are systematically investigated by advanced in situ and operando characterizations. Finally, the future trends and perspectives with an emphasis on commercialization of Si-based electrodes are provided. Si-based anode materials will be key in helping keep up with the demands for higher energy density in the coming decades.

Recent Progress on the Alloy-Based Anode for Sodium-Ion Batteries and Potassium-Ion Batteries

High-energy batteries with low cost are urgently needed in the field of large-scale energy storage, such as grid systems and renewable energy sources. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) with alloy-based anodes provide huge potential due to their earth abundance, high capacity, and suitable working potential, and are recognized as attractive alternatives for next-generation batteries system. Although some important breakthroughs have been reported, more significant improvements are still required for long lifetime and high energy density. Herein, the latest progress for alloy-based anodes for SIBs and PIBs is summarized, mainly including Sn, Sb, Ge, Bi, Si, P, and their oxides, sulfides, selenides, and phosphides. Specifically, the material designs for the desired Na⁺ /K⁺ storage performance, phase transform, ionic/electronic transport kinetics, and specific chemical interactions are discussed. Typical structural features and research strategies of alloy-based anodes, which are used to facilitate processes in battery development for SIBs and PIBs, are also summarized. The perspective of future research of SIBs and PIBs is outlined.

Catalytic separators with Co–N–C nanoreactors for high-performance lithium–sulfur batteries

An atomically dispersed supported metal catalyst with a Co–N₄ structure on active carbon (Co–N–C/AC) is prepared and introduced to modify the separators of Li–S batteries.

Bright Infrared-to-Ultraviolet/Visible Upconversion in Small Alkaline Earth-Based Nanoparticles with Biocompatible CaF2 Shells

Upconverting nanoparticles (UCNPs) are promising candidates for photon-driven reactions, including light-triggered drug delivery, photodynamic therapy, and photocatalysis. Herein, we investigate the NIR-to-UV/visible emission of sub-15 nm alkaline-earth rare-earth fluoride UCNPs (M1-x Lnx F2+x, MLnF) with a CaF2 shell. We synthesize 8 alkaline-earth host materials doped with Yb3+ and Tm3+ , with alkaline-earth (M) spanning Ca, Sr, and Ba, MgSr, CaSr, CaBa, SrBa, and CaSrBa. We explore UCNP composition, size, and lanthanide doping-dependent emission, focusing on upconversion quantum yield (UCQY) and UV emission. UCQY values of 2.46 % at 250 W cm-2 are achieved with 14.5 nm SrLuF@CaF2 particles, with 7.3 % of total emission in the UV. In 10.9 nm SrYbF:1 %Tm3+ @CaF2 particles, UV emission increased to 9.9 % with UCQY at 1.14 %. We demonstrate dye degradation under NIR illumination using SrYbF:1 %Tm3+ @CaF2 , highlighting the efficiency of these UCNPs and their ability to trigger photoprocesses.

Co-Construction of Sulfur Vacancies and Heterojunctions in Tungsten Disulfide to Induce Fast Electronic/Ionic Diffusion Kinetics for Sodium-Ion Batteries

Engineering novel electrode materials with unique architectures has a significant impact on tuning the structural/electrochemical properties for boosting the performance of secondary battery systems. Herein, starting from well-organized WS₂ nanorods, an ingenious design of a one-step method is proposed to prepare a bimetallic sulfide composite with a coaxial carbon coating layer, simply enabled by ZIF-8 introduction. Rich sulfur vacancies and WS₂ /ZnS heterojunctions can be simultaneously developed, that significantly improve ionic and electronic diffusion kinetics. In addition, a homogeneous carbon protective layer around the surface of the composite guarantees an outstanding structural stability, a reversible capacity of 170.8 mAh g^-1 after 5000 cycles at a high rate of 5 A g^-1 . A great potential in practical application is also exhibited, where a full cell based on the WS_{2- x} /ZnS@C anode and the P2-Na_2/3 Ni_1/3 Mn_1/3 O₂ cathode can maintain a reversible capacity of 89.4 mAh g^-1 after 500 cycles at 1 A g^-1 . Moreover, the underlying electrochemical Na storage mechanisms are illustrated in detail by theoretical calculations, electrochemical kinetic analysis, and operando X-ray diffraction characterization.

Rational Design of Sb@C@TiO2 Triple-Shell Nanoboxes for High-Performance Sodium-Ion Batteries

Antimony is an attractive anode material for sodium-ion batteries (SIBs) owing to its high theoretical capacity and appropriate sodiation potential. However, its practical application is severely impeded by its poor cycling stability caused by dramatic volumetric variations during sodium uptake and release processes. Here, to circumvent this obstacle, Sb@C@TiO₂ triple-shell nanoboxes (TSNBs) are synthesized through a template-engaged galvanic replacement approach. The TSNB structure consists of an inner Sb hollow nanobox protected by a conductive carbon middle shell and a TiO₂ -nanosheet-constructed outer shell. This structure offers dual protection to the inner Sb and enough room to accommodate volume expansion, thus promoting the structural integrity of the electrode and the formation of a stable solid-electrolyte interface film. Benefiting from the rational structural design and synergistic effects of Sb, carbon, and TiO₂ , the Sb@C@TiO₂ electrode exhibits superior rate performance (212 mAh g^-1 at 10 A g^-1 ) and outstanding long-term cycling stability (193 mAh g^-1 at 1 A g^-1 after 4000 cycles). Moreover, a full cell assembled with a configuration of Sb@C@TiO₂ //Na₃ (VOPO₄ )₂ F displays a high output voltage of 2.8 V and a high energy density of 179 Wh kg^-1 , revealing the great promise of Sb@C@TiO₂ TSNBs as the electrode in SIBs.

Near-Infrared Upconversion Mesoporous Tin Oxide Bio-Photocatalyst for H2O2-Activatable O2-Generating Magnetic Targeting Synergetic Treatment

Tumor hypoxia compromises the therapeutic efficacy of oxygen (O₂)-dependent treatment methods as the endogenous O₂ levels have an important influence on the production of reaction oxygen species. Herein, a synergistic multifunctional mesoporous Fe@Sn-UCNPs bio-photocatalytic nanoplatform is provided to comprehensively realize endogenous hydrogen peroxide (H₂O₂)-activatable, self-supplied O₂, photothermal performance, and near-infrared-mediated magnetic targeting PDT/PTT simultaneously for relieving tumor hypoxia. Such a nanoplatform is constructed by encapsulating magnetic Fe₃O₄ with lanthanide-ion-doped mesoporous tin oxide upconversion nanoparticles and further modified with phosphorylated serine and poly(ethylene glycol) for enhancing the biocompatibility and solubility. The nanoparticles can be activated by endogenous H₂O₂ and in situ generated O₂ to relieve hypoxia through catalytic reaction. Therefore, H₂O₂-responsive/O₂-evolving nanoparticles can elevate the O₂ level in the tumor site for an apparently enhanced PDT effect in vitro and in vivo. What is more, Fe@Sn-UCNPs demonstrate enhanced photothermal conversion efficiency based on the special nanostructure and much more circuit loops for electron transitions between Fe₃O₄ and Sn-UCNPs, and the electronic structure of Fe@Sn-UCNPs was calculated. In addition, such Fe@Sn-UCNPs also exhibit multimodality imaging performance (including photothermal, magnetic resonance, and computed tomography imaging) for monitoring and tracking the in vivo tumor therapeutic process. This work provides novel insight into the smart Fe@Sn-UCNPs as an "all-in-one" theranostic nanosystem for cancer therapy.

Transition-Metal Phosphorus Trisulfides and its Vacancy Defects: Emergence of a New Class of Anode Material for Li-Ion Batteries

In the search of suitable anode candidates with high specific capacity, favorable potential, and structural stability for lithium-ion batteries (LIBs), transition-metal phosphorus trisulfides (TMPS3 ) can be considered as one of the most promising alternatives to commercial graphite. Here, it was demonstrated that the limitations of commercial anode materials (i.e., low specific capacity, large volume change, and high lithium diffusion barrier as well as nucleation) can be circumvented by using TMPS3 monolayer surfaces. The study revealed that lithium binds strongly to TMPS3 monolayers (-2.31 eV) without any distortion of the surface, with Li@TMPS3 exhibiting enhanced stability compared with other 2D analogues (graphene, phosphorene, MXenes, transition-metal sulfides and phosphides). The binding energy of lithium was overwhelmingly enhanced with vacancy defects. The vacancy-mediated TMPS3 surfaces showed further amplification of Li binding energy from -2.03 to -2.32 eV and theoretical specific capacity of 441.65 to 484.34 mAh g-1 for MnPS3 surface. Most importantly, minimal change in volume (less than 2 %) after lithiation makes TMPS3 monolayers a very effective candidate for LIBs. Additionally, the ultralow lithium diffusion barrier (0.08 eV) compared with other existing commercial anode material proves the superiority of TMPS3 .