Emerging of Heterostructure Materials in Energy Storage: A Review

Confining CoSe/MoSe2 Heterostructures in Interconnected Carbon Polyhedrons for Superior Potassium Storage

Metal selenides hold promise as feasible anode materials for potassium-ion batteries (PIBs), but still face problems such as poor potassium storage kinetics and dramatic volume expansion. Coupling heterostructure engineering with structural design could be an effective strategy for rapid and stable K+ storage. Herein, CoSe/MoSe2 heterojunction encapsulated in nitrogen-doped carbon polyhedron and further interconnected by three-dimensional nitrogen-doped carbon nanofibers (CoMoSe@NCP/NCFs) is ingeniously constructed. The abundant CoSe/MoSe2 heterointerfaces equipped with built-in electric fields and unique interconnected carbon polyhedrons (convenient electron/ion transfer pathway and robust mechanical buffer) promote the reaction kinetics and bolster the structural robustness. Accordingly, the CoMoSe@NCP/NCFs composite exhibits outstanding cycle life, with a capacity of 206 mAh g-1 preserved after 2500 cycles at 2 A g-1. Besides, CoMoSe@NCP/NCFs also achieves decent rate performance with 161 mAh g-1 at 10 A g-1. This research demonstrates a viable approach for constructing superior PIB anodes with both fast kinetics and high stability.

Constructing a NiCoO/NiCoP Heterostructure with a Built-In Electric Field for High-Performance Supercapacitors

Constructing heterostructures is a powerful way to improve the performance of electrode materials for supercapacitors. Herein, a compact NiCoO2/NiCoP heterostructure (NiCoO/P) with a 3D porous network architecture was prepared via simple electrodeposition followed by an in situ phosphorization strategy. The strong built-in electric field at the heterointerface, coupled with the synergistic effects of NiCoO2 and NiCoP, could endow abundant active sites, improve the charge transmission and OH- absorption, and significantly enhancing electrochemical performance. Thanks to the unique 3D network structure and the synergy of the two components, the optimal NiCoO/P5 achieved a high specific charge (1265.6 C g-1) at 1.0 A g-1 and a stable cycling lifetime with 82.3% capacity retention after 5000 cycles. Moreover, the hybrid supercapacitor using NiCoO/P5 as a positive electrode delivered a satisfactory energy density of 54.9 Wh kg-1 at 800 W kg-1 and a desirable long-term cycling lifetime. This work provides a reference for designing and synthesizing well-defined electrode materials for the energy storage field.

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.

Heterogeneous-Interface-Induced Charge Redistribution Toward Fe-Based Polyanion Cathode for Advanced Sodium-Ion Batteries

Na4Fe3(PO4)2P2O7 (NFPP) is gradually developing into one of the most commercially prospective cathode materials for sodium-ion batteries. However, the inactive phase maricite-NaFePO4 (m-NFP) normally tends to be formed during the synthesis process of NFPP, as well as the intrinsic poor electronic conductivity, which impacts the realization of high Na-storage performance. Herein, for the first time, we have constructed a heterostructure in Fe-based polyanionic cathode materials by fine-tuning the stoichiometric ratio of the Na site; the inactive phase m-NFP is fully transformed to the active Na2FeP2O7 or NFPP. In NFPP-NFPO heterogeneous composites, density functional theory calculations reveal that the charge redistribution occurs at the heterogeneous interface, leading to stronger and more uniform interactions that can strengthen the structural stability and enhance the charge transport kinetics. Benefiting from the heterogeneous intergrowth structure and the formation of the electrochemically active phase, a high discharge specific capacity, ultralong cycle life (71.4% capacity retention after 10,000 cycles at 50 C), ultrafast rate capability (60.2 mAh g-1 at 200 C), and impressive high-temperature tolerance have been achieved. This work achieves heterogeneous composites by manipulation of the phase composition, providing a new approach for designing high-performance polyanionic cathodes for sodium-ion batteries.

Transition metal phosphide/ molybdenum disulfide heterostructures towards advanced electrochemical energy storage: recent progress and challenges

Transition metal phosphide @ molybdenum disulfide (TMP@MoS2) heterostructures, consisting of TMP as the core main catalytic body and MoS2 as the outer shell, can solve the three major problems in the field of renewable energy storage and catalysis, such as lack of resources, cost factors, and low cycling stability. The heterostructures synergistically combine the excellent conductivity and electrochemical performance of transition metal phosphides with the structural robustness and catalytic activity of molybdenum disulfide, which holds great promise for clean energy. This review addresses the advantages of TMP@MoS2 materials and their synthesis methods-e.g., hydrothermal routes and chemical vapor deposition regarding scalability and cost. Their electrochemical energy storage and catalytic functions e.g., hydrogen and oxygen evolution reactions (HER and OER) are also extensively explored. Their potential within battery and supercapacitor technologies is also assessed against leading performance metrics. Challenges toward industry-scale scalability, longevity, and environmental sustainability are also addressed, as are optimization and large-scale deployment strategies.

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.

Morphology-Tunable Binary Transition Metal Oxide Heterostructure@Carbon Composites for Lithium-Ion Batteries

Heterostructures of binary and unary transition metal oxides (B and UTMOs) have demonstrated excellent electrochemical performance in lithium-ion batteries (LIBs) due to synergistic effects; however, there remains a lack of research combining multiple strategies for synergy enhancement. Herein, we present the development of crystallinity-controlled heterostructures based on nickel and cobalt oxides (NiCo2O4/NiO and NiO/Co3O4) with different morphologies (urchin- and flower-like structures, e.g., U-NiCo2O4/NiO and F-NiCo2O4/NiO) to investigate the influence of heterostructure combinations and morphologies on electrochemical performance in LIBs. The morphologies of the heterostructures were controlled by adjusting the fluoride concentration during the synthesis of the nickel-cobalt (Ni-Co) precursor, while heterostructure combinations were regulated by heat treatment under specific conditions. When used as anodes for LIBs, electrochemical analyses revealed that the carbon-coated urchin-like U-NiCo2O4/NiO (U-NiCo2O4/NiO@C) sample provided more efficient charge transfer and a shorter Li-ion transport pathway compared to its counterpart (F-NiCo2O4/NiO@C) due to its high surface area and distinctive morphological features. In addition, U-NiCo2O4/NiO@C exhibited superior electrochemical performance as an anode in LIBs than U-NiO/Co3O4@C, indicating that the advantageous effects of BTMO over UTMO can effectively enhance LIB performance. This facile synthesis approach provides a foundation for morphology-controlled heterostructures in the development of high-performance anode materials for LIB applications.

Synthesis of a hollow MoSe2@MXene anode material for sodium-ion batteries

MXene and MoSe2 as a novel two-dimensional transition metal carbide and selenide, respectively, are widely used in battery electrodes. In this study, MoSe2 nanoflakes were grown in situ on hollow MXene spheres via a hydrothermal method. The obtained hollow 3D spherical MoSe2@MXene composite exhibits outstanding rate performance and cycling stability as the sodium-ion battery anode. At a current density of 1 A g-1, it achieves a specific capacity of 350.7 mA h g-1 after 1000 cycles with a retention rate of 93.7%. Even at a high current density of 10 A g-1, the specific capacity remains at 224.2 mA h g-1. The outstanding electrochemical performance of the MoSe2@MXene composite is primarily attributed to the synergistic interaction between MoSe2 and the MXene, which significantly reduces the self-aggregation of the MXene and MoSe2 and effectively enhances the diffusion and migration rates of sodium ions.

Stochastically Broken Inversion Symmetry of Van der Waals Topological Insulator for Nanoscale Physically Unclonable Functions

Owing to the exotic state of quantum matter, topological insulators have emerged as a significant platform for new-generation functional devices. Among these topological insulators, tetradymites have received significant attention because of their van der Waals (vdW) structures and inversion symmetries. Although this inversion symmetry completely blocks exotic quantum phenomena, it should be broken down to facilitate versatile topological functionalities. Recently, a Janus structure is suggested for asymmetric out-of-plane lattice structures, terminating the heterogeneous atoms at two sides of the vdW structure. However, the synthesis of Janus structures has not been achieved commercially because of the imprecise control of the layer-by-layer growth, high-temperature synthesis, and low yield. To overcome these limitations, plasma sulfurization of vdW topological insulators has been presented, enabling stochastic inversion asymmetry. To take practical advantage of the random lattice distortion, physically unclonable functions (PUFs) have been suggested as applications of vdW Janus topological insulators. The sulfur dominance is experimentally demonstrated via X-ray photoelectron spectroscopy, hysteresis variation, cross-sectional transmission electron microscopy, and adhesion energy variation. In conclusion, it is envisioned that the vdW Janus topological insulators can provide an extendable encryption platform for randomized lattice distortion, offering on-demand stochastic inversion asymmetry via a single-step plasma sulfurization.

Engineering Bi/V/Mo-Based Multicomponent Heterostructure Electrocatalyst Toward Robust Lithium-Sulfur Batteries and Mechanistic Insights into the Self-Reconstruction

The sluggish reaction kinetics and formidable shuttle effect of soluble lithium polysulfides (LiPSs) are thorny problems for the future industrialization of lithium-sulfur (Li-S) batteries. Therefore, exploring efficient electrocatalysts to capture LiPSs and accelerate their conversion is highly desirable yet tremendously challenging. Herein, a high-efficiency Bi/Bi2O3/VMoN@rGO electrocatalyst with multifunctional active sites and multilevel heterointerfaces is elaborately designed for Li-S batteries. Noteworthy, the multilevel heterointerfaces can greatly modulate the electron distribution, facilitate the charge transfer, optimize the chemical absorption, and enhance the intrinsic activity, while rGO contributes to high electrical conductivity, sufficient active sites, and robust structural stability. Thanks to the synergy of different components, Li-S batteries employing the Bi/Bi2O3/VMoN@rGO functional separators exhibit impressive electrochemical performance and high sulfur utilization even under high sulfur loading. More importantly, it is discovered that Bi and Bi2O3 experience an electrochemical phase evolution to generate Bi2S3 with amorphous and crystalline phases, thereby bringing in unexpected performance enhancement. Furthermore, experimental results and theoretical calculations authenticate that a reduced Li2S decomposition energy barrier is achieved after the in situ electrochemical reconstruction. This work not only provides new mechanistic insights into developing high-efficiency sulfur electrocatalysts but also sheds light on regulating the catalytic activity via self-reconstruction.

Heterointerface with Continuous Channels Enables Fast Na+ Transport in Layered Na2Ti3O7

High-power sodium-ion batteries are essential for grid energy storage; however, they are generally limited by Na+ transport. Herein, we tailor a highly matched heterostructure (MgTi3O7@Na2Ti3O7) via a facile in situ synthesis method. The similar crystal structures of Na2Ti3O7 and MgTi3O7 creat continuous Na+ diffusion channels at the heterointerface, and the interactions at the interface creat a built-in interface electric field with a direction from MgTi3O7 to Na2Ti3O7. As a result, the particular heterointerface enable rapid Na+ diffusion in the MgTi3O7@Na2Ti3O7 electrode. The heterostructure engineering regulate the electrochemical reaction mechanism, leading to the solid solution reaction in the MgTi3O7@Na2Ti3O7 electrode, facilitating rapid Na+ transport. Therefore, the MgTi3O7@Na2Ti3O7 electrode exhibits an excellent rate capability (123 mAh/g at 20 C) and cycling performance. This work highlights the importance of a heterointerface with continuous channels in overcoming Na+ transport limitations in electrodes and could serves as a guide for designing a heterointerface for high-power sodium-ion batteries.

Co/Co3O4@NC-CNTs modified separator of Li-S battery achieving the synergistic effect of adsorption-directional migration-catalysis via built-in electric field

The shuttle effect of lithium polysulfides (LiPSs) and sluggish sulfur conversion kinetics have seriously hindered the commercial application of lithium-sulfur (Li-S) batteries. Currently, the adsorption and catalysis processes are emphasized; however, the diffusion process is often neglected. The delayed diffusion of the adsorbed LiPSs significantly reduce battery performance. Herein, the directional migration of Sn2- was realized by adjusting the characteristics of heterostructure materials. The heterostructure consists of Co with a high Fermi level and excellent catalytic activity and Co3O4 with a low Fermi level and strong adsorption ability. This configuration regulated the direction of the built-in electric field (BIEF) at the heterogeneous interface, which promoted the migration of Sn2- from Co3O4 to Co side and realised a continuous "adsorption-directional migration-catalysis" mechanism. Experimental and theoretical results indicated that the Co/Co3O4 heterostructure modified by nitrogen-doped carbon nanotubes (Co/Co3O4@NC-CNTs), as the separator of Li-S batteries, not only enhanced the adsorption of LiPSs but also accelerated the kinetic conversion process. Consequently, the battery modified by the Co/Co3O4@NC-CNTs separator exhibited a high initial specific capacity of 1423 mAh g-1 at 0.2C, and maintained 735.5 mAh g-1 at a current density of 1C after 400 cycles.

Amorphous/Crystalline Heterostructured Nanomaterials: An Emerging Platform for Electrochemical Energy Storage

With the expanding adoption of large-scale energy storage systems and electrical devices, batteries and supercapacitors are encountering growing demands and challenges related to their energy storage capability. Amorphous/crystalline heterostructured nanomaterials (AC-HNMs) have emerged as promising electrode materials to address these needs. AC-HNMs leverage synergistic interactions between their amorphous and crystalline phases, along with abundant interface effects, which enhance capacity output and accelerate mass and charge transfer dynamics in electrochemical energy storage (EES) devices. Motivated by these elements, this review provides a comprehensive overview of synthesis strategies and advanced EES applications explored in current research on AC-HNMs. It begins with a summary of various synthesis strategies of AC-HNMs. Diverse EES devices of AC-HNMs, such as metal-ion batteries, metal-air batteries, lithium-sulfur batteries, and supercapacitors, are thoroughly elucidated, with particular focus on the underlying structure-activity relationship among amorphous/crystalline heterostructure, electrochemical performance, and mechanism. Finally, challenges and perspectives for AC-HNMs are proposed to offer insights that may guide their continued development and optimization.

Promoting Photocatalytic Hydrogen Evolution by Stabilization of Excited Triplet States and Enhancement of Internal Electric Field at Dye/PCN Interface

The heterojunction photocatalysts composed of organic dyes and polymeric carbon nitride (PCN) have great potential for photocatalytic hydrogen evolution (PHE). However, serious charge recombination exists at the dye/PCN interface for the large gaps in time scales and the poor driving force of charge transfer process. Herein, both the excited triplet states of organic dyes with long lifetimes and strong internal electric fields (IEF) as charge transfer driving forces are achieved by the construction of high dipole moments with aromatic-core engineering, and modulation of dye aggregates by alkyl modification. Accordingly, PHE efficiency can achieve up to 833.49 μmol/h, over 36-fold that of PCN/Pt (23.34 μmol/h) under the same conditions. The relationship between molecular structures and PHE performance has been systematically investigated by the photophysical properties of organic dyes and the strength of IEF at dye/PCN interface. It afforded an efficient strategy to balance the charge transfer process in PHE systems, which can guide the molecular design of organic dyes with optimized aggregated behaviors and stable excited triplet states.

The Accurate Synthesis of a Multiscale Metallic Interface on Graphdiyne

The accurate construction of composite material systems containing graphdiyne (GDY) and other metallic materials has promoted the formation of innovative structures and practical applications in the fields of energy, catalysis, optoelectronics, and biomedicine. To fulfill the practical requirements, the precise formation of multiscale interfaces over a wide range, from single atoms to nanostructures, plays an important role in the optimization of the structural design and properties. The intrinsic correlations between the structure, synthesis process, characteristic properties, and device performance are systematically investigated. This review outlines the current research achievements regarding the controlled formation of multiscale metallic interfaces on GDY. Synthetic strategies for interface regulation, as well as the correlation between the structure and performance, are presented. Furthermore, innovative research ideas for the design and synthesis of functional metal-based materials loaded onto GDY-based substances are also provided, demonstrating the promising application potential of GDY-based materials.

Remodel Heterogeneous Electrical Microenvironment at Nano-Scale Interface Optimizes Osteogenesis by Coupling of Immunomodulation and Angiogenesis

Immunomodulation is essential for implants to regulate tissue regeneration, while bioelectricity plays a fundamental role in regulating immune activities. Under natural preferences, the bone matrix electrical microenvironment is heterogeneous in the nanoscale, which provides fundamental electrical cues to regulate bone immunity and regenerative repair. However, remodeling bone nanoscale heterogeneous electrical microenvironment remains a challenge, and the underlying immune modulation mechanism remains to be explored. In this research, in situ discretely distributed nano-heterojunctions are constructed on titanium oxide nanofibers to mimic the heterogeneous electrical microenvironment exhibited by bone collagen fibers. The material is identified to directly regulate calcium ion channeling for anti-inflammatory polarization of macrophages. Surprisingly, the highly biomimetic heterogeneous electrical microenvironment can induce a pro-angiogenic phenotypic transformation of macrophages, leading to enhanced neo-vascularization at the early stage of osteogenesis. Mechanistic exploration identifies that PI3K signaling pathway-mediated FGF2 secretion may partially explain for strengthened coupling of immunomodulation and angiogenesis, which optimizes subsequent bone regeneration. These findings highlight the significance of biomimetic heterogeneous electrical cues on immune-modulation and provide a design principle for future electroactive implant materials.

Achieving Dendrite-Free Lithium Metal Batteries by Constructing a Dense Lithiophilic Cu1.8Se/CuO Heterojunction Tip

Lithium (Li) metal batteries (LMBs) have garnered widespread attention due to their high specific capacity. However, the growth of lithium dendrite severely limits their practical applications. Herein, a novel strategy is proposed to regulate the overall potential strength and lithium ions (Li+) concentration on the surface of the current collector by utilizing densely distributed tip effects. This concept is exemplified through the construction of lithiophilic Cu1.8Se/CuO heterojunction needle array on the Cu foil, ultimately achieving dendrite-free lithium deposition. Based on the simulation in COMSOL multiphysics and experimental research, this design is demonstrated to enrich Li+ on the current collector surface, delay the formation of space charge regions, and mitigate the growth of lithium dendrites. Additionally, a built-in electric field (BIEF) triggered by the heterointerface between Cu1.8Se and CuO further alleviates the Li+ concentration gradient on the electrode surface, achieving uniform bottom-up deposition of Li within the array structure. Consequently, the symmetrical cell exhibits an ultra-long cycle life of 2400 h (1 mA cm-2, 1 mAh cm-2) with an extremely low overpotential of 13 mV. Furthermore, full batteries using LiFePO4 as the cathode exhibit superior cycle stability and rate performance. This study presents a promising approach for designing dendrite-free current collectors in LMBs.

Chemically-Linked Heterostructures of Palladium Nanosheets and 2H-MoS2

The burgeoning field of 2D heterostructures targets the combination of 2D materials with 3D, 1D, or 0D nanomaterials. Among the most popular 2D materials, the 2H polytype of molybdenum disulfide (MoS2) features a well-defined bandgap that becomes direct at the monolayer level, which can be exploited for photodetection. A notable limitation of 2H-MoS2 is its curtailed absorbance beyond the visible range. Here, a covalently-linked Pd nanosheet (PdNS)/functionalized MoS2 (f-MoS2) heterostructure is introduced, leveraging PdNS infrared-absorbing properties to surmount this constraint. A bifunctional molecule, featuring a maleimide for attachment to MoS2 and a phenyl bromide for connection to PdNS, enables the synthesis of the heterostructure. Comprehensive spectroscopic and microscopic characterization shed light on the structure of PdNS@f-MoS2 and the electronic interaction between its components. Prototype devices show an enhancement in the width and intensity of the optoelectronic response of PdNS@f-MoS2 in the infrared, up to 1700 nm. In comparison, a van der Waals heterostructure with the same components shows poorer photoresponse. The results prove that the covalent linkage of metal nanostructures to 2D materials is a promising approach to build mixed-dimensional heterostructures.

Electric-Field-Driven Redistribution of Carriers on Catalyst Particles to Improve Photocatalytic Performance

The photocatalytic performance is primarily determined by carrier separation efficiency. Applying electric fields to enhance carrier separation efficiency and thereby boost catalytic performance has emerged as a promising approach. However, the carrier behavior on catalyst particles under electric fields was still hardly acknowledged. Herein, using single-molecule fluorescence microscopy with high spatiotemporal resolution, the redistribution behavior of carriers on catalyst particles under an electric field was visualized for the first time, which was closely related to the direction and intensity of the electric field. Single-molecule kinetics of the photocatalytic redox reactions induced by carriers have been further obtained, and the results showed that the external electric field had an obvious regulating role in the conversion process and desorption process in this work, which was attributed to the dynamic redistribution of carriers. The improvement of photocatalytic hydrogen evolution reaction (HER) activity further supports the impact of the external electric field on photocatalysis. This work offers new insight into the microscopic regulation mechanism of photocatalytic activity by electric fields and provides new methods for studying the structure-activity relationship in photocatalytic processes.

Incorporation of Fe/FeOx Nanoparticles into Interlinked N-Doped Porous Carbon Nanofiber Networks to Realizing Sequential Catalytic Conversion of Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries (LSBs) with energy density (2600 Wh/kg) much higher than typical Li-ion batteries (150-300 Wh/kg) have received considerable attention. However, the insulation nature of solid sulfur species and the high activation barrier of lithium polysulfides (LiPSs) lead to slow sulfur redox kinetics. By the introduction of catalytic materials, the effective adsorption of LiPSs, and significantly reduced conversion, energy barriers are expected to be achieved, thereby sharpening electrochemical reaction kinetics and fundamentally addressing these challenges. In this work, a multifunctional catalyst consisting of highly dispersed heterostructure Fe-Fe2O3 nanoparticles was synthesized and introduced to the LSB. Experimental and theoretical analyses revealed that the spontaneous interfacial charge redistribution, resulting in moderate polysulfide adsorption, facilitates the transfer of polysulfides and diffusion of electrons at heterogeneous interfaces. This catalyst achieves sequential catalytic processes on polysulfides with different components. Furthermore, the reduced conversion energy barriers enhanced the catalytic activity of Fe/Fe2O3-NG for expediting LiPS conversion. Consequently, the battery exhibited long-term stability for 300 cycles with 0.03% capacity decay per cycle at 5C. This work provides in-depth insight into the fundamental design principles of effective catalysts for LSBs.

Hollow Porous Co0.85Se/ZnSe@MXene Anode with Multilevel Built-in Electric Fields for High-Performance Sodium Ion Capacitors

Sodium ion capacitors (SICs) are promising candidates in energy storage for their remarkable power and energy density. However, the inherent disparity in dynamic behavior between the sluggish battery-type anodes and the rapid capacitor-type cathodes constrained their performance. To address this, we fabricated a hollow porous Co0.85Se/ZnSe@MXene anode featuring multiheterostructure, utilizing facile etching and electrostatic self-assembly strategies. The hollow porous structure and multiple heterointerfaces stabilize the anode by mitigating the volume changes. Density functional theory (DFT) calculations further revealed that induced multilevel built-in electric fields facilitate the formation of rapid ion diffusion pathways and reduce the Na+ adsorption energy, thereby boosting Na+/electron transport kinetics. The fabricated TA-Co0.85Se/ZnSe@MXene anode demonstrates outstanding long-term cycling stability of 406 mA h g-1 after 1000 cycles at 1 A g-1, with an ultrahigh rate performance of 288 mA h g-1 at 10 A g-1. When paired with the active carbon (AC) cathode, the SICs deliver extraordinary energy/power densities of 144 W h kg-1 and 12000 W kg-1, maintaining over 80% capacity retention at 1 A g-1 after 10000 cycles. This innovative strategy of engineering multiheterostructured anode with the induced multilevel built-in electric fields holds significant promise for advancing high-energy and high-power energy storage systems.

Electric Field and Nanocontact Effects in Metal-Organic Framework/Li6.4La3Zr1.4Ta0.6O12 Ionic Conductors for Fast Interfacial Lithium-Ion Transport Kinetics

The slow ion transport kinetics inside or between the nanofillers in composite polymer electrolytes (CPEs) lead to the formation of lithium dendrites for solid-state lithium batteries. To address the critical issues, CPEs (U@UNL) composed of a UIO-66@UIO-66-NH2 (U@UN) core-shell heterostructure and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) filler is designed. Due to the different band structures of the U@UN heterostructure, a built-in electric field is constructed to promote the transfer kinetics of carriers. Besides, the introduction of LLZTO facilitates the formation of a close nanometer contact interface between U@UN and LLZTO, reducing interface impedance and accelerating the lithium-ion transfer rate. As a benefit from the built-in electric field and the nanometer contact interface, U@UNL exhibits a wide electrochemical window of 5.17 V, a large lithium-ion transference number of 0.76, and a high ionic conductivity of 3.50 × 10-3 S cm-1. Consequently, the U@UNL electrolyte possesses excellent interfacial stability against Li metal after 1200 h at 0.1 mA cm-2 and shows a high specific capacity of 160.2 and 152.6 mAh g-1 at 0.5 and 1 C, respectively. This work proposes a complete strategy for building high-performance solid-state lithium batteries by a built-in electric field and nanometer contact interface between U@UN and LLZTO.

Heterostructure Engineering for Aluminum-Ion Batteries: Mechanism, Challenge, and Perspective

Benefiting from high volumetric capacity, environmental friendliness, and high safety, aluminum-ion batteries (AIBs) are considered to be promising battery system among emerging electrochemical energy storage technologies. As an important component of AIBs, the cathode material is crucial to decide the energy density and cycle life of AIBs. However, single-component cathode materials are unable to achieve a balance between cycling stability and rate performance. In recent years, research on heterostructure cathode materials has gained significant attention in AIBs. By harnessing the synergistic effects of heterostructure, the shortcomings of individual materials can be overcome, contributing to improved conductivity and structural stability. This review offers a detailed insight into the Al-storage mechanism of heterostructure cathodes, and provides an overview of the current research progresses on heterostructure cathode materials for AIBs. Starting from the relationship between the microstructure and electrochemical performance of heterostructure materials, the different structure design strategies are elaborated. Besides, the challenges faced by heterostructure are summarized, and their potential impact on the future of the energy storage industry is anticipated. This review provides the guidelines for the future research of heterostructure as cathode materials for AIBs.

Lateral Heterostructures Fabricated via Artificial Pressure Gradient

Hydrostatic conditions are generally pursued in high-pressure research, maintained to prevent the intrinsic pressure gradient on the culets of diamond anvil cells (DACs) from introducing heterogeneity to the structure and physical properties of the regulated materials. Here, a pioneering route to fabricate lateral heterostructures is proposed via artificial pressure gradients intentionally designed in DACs. Under the tailored pressure gradients, different structural phases emerge in distinct parts of the material, resulting in the formation of heterostructures. Harnessing the polymorphic transition nature of violet phosphorus under high pressure, violet/blue and violet/black phosphorus lateral heterostructures with different electrical properties have been successfully prepared by the pressure gradient method. This achievement highlights the potential of artificial pressure gradients as a portable and universal strategy for the fabrication of lateral heterostructures, shedding new light on the preparation and regulation of lateral heterostructures across a wider range of materials.

Pillar-Supported 2D Layered MOFs with Abundant Active-Site Distributions for High-Performance Alkaline Supercapacitors

The development of two-dimensional (2D) layered metal-organic frameworks (MOFs) through precise molecular-level design and synthesis has emerged as a prominent research endeavor. However, the utilization of MOFs in their pristine form as electrodes for supercapacitors poses a significant challenge due to their limited tolerance in alkaline environments. To address these issues, we have developed Co- and Cu-based pillar-layered MOFs by regulating the structure of their inner layers through introducing an alkaline N-containing "pillar" to enhance the performance of alkaline supercapacitor electrodes. From the microstructure study and theoretical calculation, the high-density redox centers and efficient chemical bonding modes of Co-MOF determine a unique electron conduction pathway, resulting in excellent energy storage performance. This study underscores the significance of chemical bonding modes and active-site distribution in enhancing the energy storage capabilities of pillar-layered MOFs in alkaline environments, presenting a promising approach for the development of high-performance MOF-based materials for supercapacitor applications.

Multiple Heterointerfaces and Heterostructure Engineering in MXene@Co-P-S Hybrids Promote High-Performance Sodium-Ion Half/Full Batteries

In this paper, heterogeneous cobalt phosphosulfide (Co4S3/Co2P) nanocrystals anchoring on few-layered MXene nanosheets (MXene@Co4S3/Co2P) were prepared by in situ growth and the subsequent high-temperature phosphorization/sulfidation processes. Thanks to the synergistic effect and the abundant phase interfaces of Co4S3, Co2P, and MXene, the electron transfer and Na+ diffusion processes were greatly accelerated. Meanwhile, the high electrical conductivity of MXene nanosheets and the heterogeneous structure of Co4S3/Co2P effectively avoided the MXene restacking and the agglomeration of phosphosulfide particles, thus mitigating volumetric expansion during charging and discharging. The results show that the MXene@Co4S3/Co2P heterostructure presents good rate capability (251.08 mAh g-1 at 1 A g-1) and excellent cycling stability (198.69 mAh g-1 after 407 cycles at 5 A g-1). Finally, the storage mechanism of Na+ in the heterostructure and the multistep phase transition reaction were determined by ex situ X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) analyses. This study provides a new perspective on the formation of metal phosphosulfide and MXene hybrids with multiple heterointerfaces as well as demonstrates MXene@Co4S3/Co2P composites as the promising anode material in sodium-ion batteries.

Heterogeneous Interface Design with Oxygen Vacancy-Rich Assistance High-Capacity Titanium-Based Oxide Anode Materials for Sodium-Ion Batteries

Researchers are paying more attention to sodium-ion batteries (SIBs) because of their abundant supply of sodium resources and affordable price. TiO2 offers excellent safety and a long lifespan as an anode material for SIBs. However, the process kinetics is slow due to its limited Na+ storage efficiency, weak conductivity, and irreversible Na+ capture. In order to address these issues, this review uses a mix of the template approach and the double-hydrolysis method to manage the structure and diffusion of TiO2-based anode materials by synthesizing FeTiO3/TiO2 heterostructured double-shell microspheres (FTO). Through the built-in electric field effect caused by their heterostructures, FTO materials improve reaction kinetics, boost electronic conductivity, and lower the diffusion energy barrier of Na+. Their distinctive double-shell structure can increase electrolyte infiltration, shorten the diffusion distance between ions and electrons, and accommodate volume expansion during cycling. Furthermore, the irreversible capture of Na+ and the unfavorable interactions between the surface active site and electrolyte can be successfully inhibited by FTO heterostructures. FTO has an exceptionally high capacity (reaching 362.7 mA h g-1 after 60 cycles at 20 mA g-1) and excellent cycle stability (with a decay rate of 0.0061% after 1000 cycles at 2 A g-1). The strategy of constructing heterogeneous interfaces assists with high-performance SIB anode design.

Single-Atom 3d Transition Metals on SnO2 as Model Cell for Conversion Mechanism: Revealing Thermodynamic Catalytic Effects on Enhanced Na Storage of Heterostructures

Since the discovery in 2000, conversion-type materials have emerged as a promising negative-electrode candidate for next-generation batteries with high capacity and tunable voltage, limited by low reversibility and severe voltage hysteresis. Heterogeneous construction stands out as a cost-effective and efficient approach to reducing reaction barriers and enhancing energy density. However, the second term introduced by conventional heterostructure inevitably complicates the electrochemical analysis and poses great challenges to harvesting systematic insights and theoretical guidance. A model cell is designed and established herein for the conversion reactions between Na and TMSA-SnO2, where TMSA-SnO2 represents single atom modification of eight different 3d transition elements (V, Cr, Mn, Fe, Co, Ni, Cu or Zn). Such a model unit fundamentally eliminates the interference from the second phase and thus enables independent exploration of activation manifestations of the heterogeneous architecture. For the first time, a thermodynamically dependent catalytic effect is proposed and verified through statistical data analysis. The mechanism behind the unveiled catalytic effect is further elucidated by which the active d orbitals of transition metals weaken the surface covalent bonds and lower the reaction barriers. This research provides both theoretical insights and practical demonstrations of the advanced heterogeneous electrodes.

First-principles study of valley splitting of transition-metal dichalcogenides in MX2/CrI3 (M = W, Mo; X = S, Se, Te) van der Waals heterostructures

The rapid development of valleytronics makes the application of two-dimensional (2D) transition-metal dichalcogenides (TMDs) in valley electronics important. As a new degree of freedom, valley splitting of TMDs has been achieved and tuned by many methods. Among them, using the magnetic proximity effect (MPE) generated from the interface of 2D van der Waals (vdW) heterostructures stacked with TMDs and one magnetic substrate, valley splitting can be achieved through band edge lifting at the adjacent K/K' valley. However, the comprehensive mechanism and strategy of valley splitting in 2D TMD heterostructures need to be explored ulteriorly. Here, we systematically investigated valley splitting of MX2 in MX2/CrI3 (M = W, Mo; X = S, Se, Te) vdW heterostructures using first-principles approaches. We demonstrated that twisting is an effective method to enhance valley splitting in MX2/CrI3 vdW heterostructures. Furthermore, we also showed a ∼10 times enhancement in valley splitting by changing the stacking patterns between WTe2 and CrI3 layers. We attribute this to the interlayer magnetic and electronic coupling between the two layers of the vdW heterostructure. The present results provide a theoretical basis and effective methods for tuning valley splitting 2D TMD heterostructures.

Heterogeneous NASICON-Type Cathode With Reversible Multielectron Reaction for High-Performance Sodium-Ion Batteries

Na superionic conductor (NASICON)-structured compounds demonstrate great application potential by their robust framework and compositional diversity. However, they are blamed for the mediocre energy density, and achieving both multielectron reaction and good cycling stability simultaneously is challenging. Herein, a novel heterogeneous Na4Fe3(PO4)2(P2O7)/Na2VTi(PO4)3 (NFPP/NVTP) material with stable multielectron reaction is constructed by spray drying technology. The mutual promotion effect of intergrowth structures effectively improves the purity and the crystallization of NFPP/NVTP during the fabrication process, which is beneficial to the high capacity and cycling stability. As a result, the optimized NFPP/NVTP demonstrates a high reversible capacity of 155.3 mAh g-1 at 20 mA g-1 and outstanding cycling stability with 82.9% capacity retention over 2500 cycles at 1 A g-1, which are much superior to those of NFPP and NVTP individually. Even in full cell configuration, the energy density remains high at ≈380 Wh kg-1 based on the cathode mass. The high capacity of NFPP/NVTP is also attributed to the successive reduction/oxidation mechanism involving the introduction of Ti3+ and interfacial charge redistribution effect between the heterogeneous phases, which greatly improve the electronic and ionic conductivity. Moreover, high reversible structural evolution during the multisodium storage process further guarantees excellent cycling stability.

Addressing adsorption and catalysis of lithium polysulfide via electronic distribution of molybdenum carbide host

Heterostructure engineering is considered a crucial strategy to modulate the intrinsic charge transfer behavior of materials, enhance catalytic activity, and optimize sulfur electrochemical processes. However, parsing the role of heterogeneous interface-structure-property relationships in heterostructures is still a key scientific issue to realize the efficient catalytic conversion of polysulfides. Based on this, molybdenum carbide (Mo2C) was successfully partial reduced to molybdenum metal (Mo) via a thermal reduction at high-temperature and the typical Mo-Mo2C-based Mott-Schottky heterostructures were simultaneously constructed, which realized the modulation of the electronic structure of Mo2C and optimized the conversion process of lithium polysulfides (LPS). Compared with single molybdenum carbide, the modulated molybdenum carbide acts as an electron donor with stronger Mo-S bonding strength as well as higher polysulfide adsorption energy, faster Li2S conversion kinetics, and greatly facilitates the adsorption → catalysis process of LPS. As a result, yolk-shell Mo-Mo2C heterostructure (C@Mo-Mo2C) exhibits excellent cycling performance as a sulfur host, with a discharge specific capacity of 488.41 mAh g-1 for C@Mo-Mo2C/S at 4 C and present an excellent high-rate cyclic performance accompanied by capacity decay rate of 0.08 % per cycle after 400 cycles at 2 C. Heterostructure-acting Mo2C electron distribution modulation engineering may contributes to the understanding of the structure-interface-property interaction law in heterostructures and further enables the efficient modulation of the chemical behavior of sulfur.

Design and Construction of Carbon-Coated Bimetallic Selenide Heterostructures Loaded on Reduced Graphene Oxide Substrate for Superior Lithium-Ion Storage

In this work, carbon-coated bimetallic tin-nickel selenide heterostructures loaded on reduced graphene oxide composites were prepared through a metal-organic framework-assisted strategy. The carbon coating mitigates the volume expansion and maintains the structural stability, while the introduction of reduced graphene oxide and heterojunction enhances electrical conductivity and reaction kinetics, thereby together contributing to the enhanced lithium-ion storage performance. As expected, the optimal material delivers excellent lithium-ion storage performance in terms of a high reversible capacity of 1033.4 mAh g-1 at 0.2 A g-1, outstanding rate capability, and long-term cyclability with the capacity of 726.2 mAh g-1 after 500 cycles at 1.0 A g-1 and 452.4 mAh g-1 after 1000 cycles at 2.0 A g-1. Furthermore, the electrochemical reaction mechanism of the composite is analyzed.

Using MXene as a Chemically Induced Initiator to Construct High-Performance Cathodes for Aqueous Zinc-Ion Batteries

MXene usually exhibits weak pseudo-capacitance behavior in aqueous zinc-ion batteries, which cannot provide sufficient reversible capacity, resulting in the decline of overall capacity when used as the cathode materials. Taking inspiration from polymer electrolyte engineering, we have conceptualized an in situ induced growth strategy based on MXene materials. Herein, 5.25 % MXene was introduced into the nucleation and growth process of vanadium oxide (HVO), providing the heterogeneous nucleation site and serving as an initiator to regulate the morphology and structural of vanadium oxide (T-HVO). The resulted materials can significantly improve the capacity and rate performance of zinc-ion batteries. The growth mechanism of T-HVO was demonstrated by both characterizations and DFT simulations, and the improved performance was systematically investigated through a series of in situ experiments related to dynamic analysis steps. Finally, the evaluation and comparison of various defect introduction strategies revealed the efficient, safety, and high production output characteristics of the in situ induced growth strategy. This work proposes the concept of in situ induced growth strategy and discloses the induced chemical mechanism of MXene materials, which will aid the understanding, development, and application of cathode in aqueous zinc-ion batteries.

Promoting Electrocatalytic Oxygen Reactions Using Advanced Heterostructures for Rechargeable Zinc-Air Battery Applications

In order to facilitate electrochemical oxygen reactions in electrically rechargeable zinc-air batteries (ZABs), there is a need to develop innovative approaches for efficient oxygen electrocatalysts. Due to their reliability, high energy density, material abundance, and ecofriendliness, rechargeable ZABs hold promise as next-generation energy storage and conversion devices. However, the large-scale application of ZABs is currently hindered by the slow kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). However, the development of heterostructure-based electrocatalysts has the potential to surpass the limitations imposed by the intrinsic properties of a single material. This Account begins with an explanation of the configurations of ZABs and the fundamentals of the oxygen electrochemistry of the air electrode. Then, we summarize recent progress with respect to the variety of heterostructures that exploit bifunctional electrocatalytic reactions and overview their impact on ZAB performance. The range of heterointerfacial engineering strategies for improving the ORR/OER and ZAB performance includes tailoring the surface chemistry, dimensionality of catalysts, interfacial charge transfer, mass and charge transport, and morphology. We highlight the multicomponent design approaches that take these features into account to create advanced highly active bifunctional catalysts. Finally, we discuss the challenges and future perspectives on this important topic that aim to enhance the bifunctional activity and performance of zinc-air batteries.

Strain Self-Adaptive Iron Selenides Toward Stable Na+-Ion Batteries with Impressive Initial Coulombic Efficiency

High tap density electrodes play a vital role in developing rechargeable batteries with high volumetric capacities, however, developing advanced electrodes with satisfied capacity, excellent structural stability, and achieving the resulted batteries with a high initial Coulombic efficiency (ICE) and good rate capability with long lifespan simultaneously, are still an intractable challenge. Herein, an ultrahigh ICE of 94.1% and stable cycling of carbon-free iron selenides anode is enabled with a high tap density of 2.57 g cm-3 up to 4000 cycles at 5 A g-1 through strain-modulating by constructing a homologous heterostructure. Systematical characterization and theoretical calculation show that the self-adaptive homologous heterointerface alleviates the stress of the iron selenide anodes during cycling processes and subsequently improves the stability of the assembled batteries. Additionally, the well-formed homologous heterostructure also contributes to the rapid Na+ diffusion kinetic, increased charge transfer, and good reversibility of the transformation reactions, endowing the appealing rate capability of carbon-free iron selenides. The proposed design strategy provides new insight and inspiration to aid in the ongoing quest for advanced electrode materials with high tap densities and excellent stability.

Heterointerfaces: Unlocking Superior Capacity and Rapid Mass Transfer Dynamics in Energy Storage Electrodes

Heterogeneous electrode materials possess abundant heterointerfaces with a localized "space charge effect", which enhances capacity output and accelerates mass/charge transfer dynamics in energy storage devices (ESDs). These promising features open new possibilities for demanding applications such as electric vehicles, grid energy storage, and portable electronics. However, the fundamental principles and working mechanisms that govern heterointerfaces are not yet fully understood, impeding the rational design of electrode materials. In this study, the heterointerface evolution during charging and discharging process as well as the intricate interaction between heterointerfaces and charge/mass transport phenomena, is systematically discussed. Guidelines along with feasible strategies for engineering structural heterointerfaces to address specific challenges encountered in various application scenarios, are also provided. This review offers innovative solutions for the development of heterogeneous electrode materials, enabling more efficient energy storage beyond conventional electrochemistry. Furthermore, it provides fresh insights into the advancement of clean energy conversion and storage technologies. This review contributes to the knowledge and understanding of heterointerfaces, paving the way for the design and optimization of next-generation energy storage materials for a sustainable future.

Electron-injection-engineering induced dual-phase MoO2.8F0.2/MoO2.4F0.6 heterostructure for magnesium storage

Rechargeable magnesium batteries (RMBs) have received increased attention due to their high volumetric capacity and safety. Nevertheless, the sluggish diffusion kinetics of highly polarized Mg2+ in host lattices severely hinders the development of RMBs. Herein, we report an electron injection strategy for modulating the Mo 4d-orbital splitting manner and first fabricate a dual-phase MoO2.8F0.2/MoO2.4F0.6 heterostructure to accelerate Mg2+ diffusion. The electron injection strategy triggers weak Jahn-Teller distortion in MoO6 octahedra and reorganization of the Mo 4d-orbital, leading to a partial phase transition from orthorhombic phase MoO2.8F0.2 to cubic phase MoO2.4F0.6. As a result, the designed heterostructure generates a built-in electric field, simultaneously improving its electronic conductivity and ionic diffusivity by at least one order of magnitude compared to MoO2.8F0.2 and MoO2.4F0.6. Importantly, the assembled MoO2.8F0.2/MoO2.4F0.6//Mg full cell exhibits a remarkable reversible capacity of 172.5 mAh g-1 at 0.1 A g-1, pushing forward the orbital-scale manipulation for high-performance RMBs.

Revealing the Two-Stage Charging Process in Sulfuric Acid Electrolyte by Molecular Dynamics Simulation

Two-dimensional MXene materials perform excellently in supercapacitor applications, but self-stacking and overlap limit their applications. Constructing a reasonable layered structure by combining MXene and graphene can effectively inhibit the restacking and overlap of MXene and improve the performance of supercapacitors. In this work, we studied the energy storage performance of a conventional MXene electrode and MXene/graphene composite electrode in sulfuric acid aqueous electrolyte by molecular dynamics (MD) simulation and analyzed their energy storage mechanisms. The simulation results reveal that the MXene/graphene composite electrode showed faster charge-discharge speed and larger capacity and had more obvious advantages as a cathode. The charging process of the composite cathode can be divided into two stages. In the first stage, SO42- and H3O+ enter the electrode as a whole in a nearly 1:2 ratio, and a unique three-layer structure is formed in the graphene area, while a large number of HSO4- leaves the electrode. In the second stage, SO42- with a part of H3O+ (ratio of 2:2 to 2:3) leave the electrode, and the three-layer structure is gradually destroyed. The cooperation of these two stages leads to a particular "concave" in the total energy change of the composite cathode. The introduction of graphene has brought about changes in ion distribution, migration mechanism, and energy change, making the MXene/graphene cathode show significant advantages in energy storage. This work is of great significance for understanding the microscopic energy storage mechanism of MXene/graphene-based electrodes.

Tunable Interfacial Electric Field-Mediated Cobalt-Doped FeSe/Fe3Se4 Heterostructure for High-Efficiency Potassium Storage

The interfacial electric field (IEF) in the heterostructure can accelerate electron transport and ion migration, thereby enhancing the electrochemical performance of potassium-ion batteries (PIBs). Nevertheless, the quantification and modulation of the IEF for high-efficiency PIB anodes currently remains a blank slate. Herein, we achieve for the first time the quantification and tuning of IEF via amorphous carbon-coated undifferentiated cobalt-doped FeSe/Fe3Se4 heterostructure (denoted UN-CoFe4Se5/C) for efficient potassium storage. Co doping can increase the IEF in FeSe/Fe3Se4, thereby improving the electron transport, promoting the potassium adsorption capacity, and lowering the diffusion barrier. As expected, the IEF magnitude in UN-CoFe4Se5/C is experimentally quantified as 62.84 mV, which is 3.65 times larger than that of amorphous carbon-coated FeSe/Fe3Se4 heterostructure (Fe4Se5/C). Benefiting from the strong IEF, UN-CoFe4Se5/C as a PIB anode exhibits superior rate capability (145.8 mAh g-1 at 10.0 A g-1) and long cycle lifespan (capacity retention of 95.1 % over 3000 cycles at 1.0 A g-1). Furthermore, this undifferentiated doping strategy can universally regulate the IEF magnitude in CoSe2/Co9Se8 and FeS2/Fe7S8 heterostructures. This work can provide fundamental insights into the design of advanced PIB electrodes.

Controlled Growth Lateral/Vertical Heterostructure Interface for Lithium Storage

Artificial heterostructures with structural advancements and customizable electronic interfaces are fundamental for achieving high-performance lithium-ion batteries (LIBs). Here, a design idea for a covalently bonded lateral/vertical black phosphorus (BP)-graphdiyne oxide (GDYO) heterostructure achieved through a facile ball-milling approach, is designed. Lateral heterogeneity is realized by the sp2-hybridized mode P-C bonds, which connect the phosphorus atoms at the edges of BP with the carbon atoms of the terminal acetylene in GDYO. The vertical connection of the heterojunction of BP and GDYO is connected by P-O-C bond. Experimental and theoretical studies demonstrate that BP-GDYO incorporates interfacial and structural engineering features, including built-in electric fields, chemical bond interactions, and maximized nanospace confinement effects. Therefore, BP-GDYO exhibits improved electrochemical kinetics and enhanced structural stability. Moreover, through ex- and in-situ studies, the lithiation mechanism of BP-GDYO, highlighting that the introduction of GDYO inhibits the shuttle/dissolution effect of phosphorus intermediates, hinders volume expansion, provides more reactive sites, and ultimately promotes reversible lithium storage, is clarified. The BP-GDYO anode exhibits lithium storage performance with high-rate capacity and long-cycle stability (602.6 mAh g-1 after 1 000 cycles at 2.0 A g-1). The proposed interfacial and structural engineering is universal and represents a conceptual advance in building high-performance LIBs electrode.

Semi-Coherent Heterointerface Engineering via In Situ Phase Transition for Enhanced Sodium/Lithium-Ions Storage

To improve ion transport kinetics and electronic conductivity between the different phases in sodium/lithium-ion battery (LIB/SIB) anodes, heterointerface engineering is considered as a promising strategy due to the strong built-in electric field. However, the lattice mismatch and defects in the interphase structure can lead to large grain boundary resistance, reducing the ion transport kinetics and electronic conductivity. Herein, monometallic selenide Fe3Se4-Fe7Se8 semi-coherent heterointerface embedded in 3D connected Nitrogen-doped carbon yolk-shell matrix (Fe3Se4-Fe7Se8@NC) is obtained via an in situ phase transition process. Such semi-coherent heterointerface between Fe3Se4 and Fe7Se8 shows the matched interfacial lattice and strong built-in electric field, resulting in the low interface impedance and fast reaction kinetics. Moreover, the yolk-shell structure is designed to confine all monometallic selenide Fe3Se4-Fe7Se8 semi-coherent heterointerface nanoparticles, improving the structural stability and inhibiting the volume expansion effect. In particular, the 3D carbon bridge between multi-yolks shell structure improves the electronic conductivity and shortens the ion transport path. Therefore, the efficient reversible pseudocapacitance and electrochemical conversion reaction are enabled by the Fe3Se4-Fe7Se8@NC, leading to the high specific capacity of 439 mAh g-1 for SIB and 1010 mAh g-1 for LIB. This work provides a new strategy for constructing heterointerface of the anode for secondary batteries.

Island-Like Heterogeneous Interface Generating Tandem Toroidal Built-In Electric Field for Efficient Potassium Ions Diffusion

For large-size potassium accommodation, heterostructure usually suffers severe delamination and exfoliation at the interfaces due to different volume expansion of two-phase during charge/discharge process, resulting in the deconstruction of heterostructures and shortened lifespan of batteries. Here, an innovative strategy is proposed through constructing a microscopic heterostructure system containing copper quantum dots (Cu QDs) highly dispersed in the triphenyl-substituted triazine graphdiyne (TPTG) substrates (TPTG@CuQDs) to solve this problem. The copper quantum dots are uniformly anchored on TPTG substrates, generating a myriad of island-like heterogeneous structures, together with tandem toroidal built-in electric field (BIEF) between every micro heterointerface. The island-like heterostructure endows both benefits of exposed contact interface and robust architecture. Generated tandem toroidal BIEF provides efficient transport pathways with lower energy barriers, reducing the diffusion resistance and facilitating the reaction kinetics of potassium ions. When used as anode, the TPTG@CuQDs exhibit highly reversible capacity and low-capacity degradation (≈0.01% over 5560 cycles at 1 A g-1). Moreover, the TPTG@CuQDs-based full cell delivers an outstanding reversible capacity of ≈110 mAh g-1 over 800 cycles at 1 A g-1. This quantum-scale heterointerface construction strategy offers a new approach toward stable heterostructure design for the application of metal ion batteries.

Stable Photo-Rechargeable Al Battery for Enhancing Energy Utilization

Photovoltaic cells (PVs) are able to convert solar energy to electric energy, while energy storage devices are required to be equipped due to the fluctuations of sunlight. However, the electrical connection of PVs and energy storage devices leads to increased energy consumption, and thus energy storage ability and utilization efficiency are decreased. One of the solutions is to explore an integrated photoelectrochemical energy conversion-storage device. Up to date, the integrated photo-rechargeable Li-ion batteries often suffer from unstable photo-active materials and flammable electrolytes under illumination, with concerns in safety risks and limited lifetime. To address the critical issues, here a novel photo-rechargeable aluminum battery (PRAB) is designed with safe ionic liquid electrolytes and stable polyaniline photo-electrodes. The integrated PRAB presents stable operation with an enhanced reversible specific capacity ≈191% under illumination. Meanwhile, a simplified continuum model is established to provide rational guidance for designing electrode structures along with a charging/discharging strategy to meet the practical operation conditions. The as-designed PRAB presents an energy-saving efficiency ≈61.92% upon charging and an energy output increment ≈31.25% during discharging under illumination. The strategy of designing and fabricating stable and safe photo-rechargeable non-aqueous Al batteries highlights the pathway for substantially promoting the utilization efficiency of solar energy.

Ti─O─C Bonding at 2D Heterointerfaces of 3D Composites for Fast Sodium Ion Storage at High Mass Loading Level

3D composite electrodes have shown extraordinary promise as high mass loading electrode materials for sodium ion batteries (SIBs). However, they usually show poor rate performance due to the sluggish Na+ kinetics at the heterointerfaces of the composites. Here, a 3D MXene-reduced holey graphene oxide (MXene-RHGO) composite electrode with Ti─O─C bonding at 2D heterointerfaces of MXene and RHGO is developed. Density functional theory (DFT) calculations reveal the built-in electric fields (BIEFs) are enhanced by the formation of bridged interfacial Ti─O─C bonding, that lead to not only faster diffusion of Na+ at the heterointerfaces but also faster adsorption and migration of Na+ on the MXene surfaces. As a result, the 3D composite electrodes show impressive properties for fast Na+ storage. Under high current density of 10 mA cm-2, the 3D MXene-RHGO composite electrodes with high mass loading of 10 mg cm-2 achieve a strikingly high and stable areal capacity of 3 mAh cm-2, which is same as commercial LIBs and greatly exceeds that of most reported SIBs electrode materials. The work shows that rationally designed bonding at the heterointerfaces represents an effective strategy for promoting high mass loading 3D composites electrode materials forward toward practical SIBs applications.

Optimized Adsorption-Catalytic Conversion for Lithium Polysulfides by Constructing Bimetallic Compounds for Lithium-Sulfur Batteries

Although lithium-sulfur batteries possess the advantage of high theoretical specific capacity, the inevitable shuttle effect of lithium polysulfides is still a difficult problem restricting its application. The design of highly active catalysts to promote the redox reaction during charge-discharge and thus reduce the existence time of lithium polysulfides in the electrolyte is the mainstream solution at present. In particular, bimetallic compounds can provide more active sites and exhibit better catalytic properties than single-component metal compounds by regulating the electronic structure of the catalysts. In this work, bimetallic compounds-nitrogen-doped carbon nanotubes (NiCo)Se2-NCNT and (CuCo)Se2-NCNT are designed by introducing Ni and Cu into CoSe2, respectively. The (CuCo)Se2-NCNT delivers an optimized adsorption-catalytic conversion for lithium polysulfide, benefitting from adjusted electron structure with downshifted d-band center and increased electron fill number of Co in (CuCo)Se2 compared with that of (NiCo)Se2. This endows (CuCo)Se2 moderate adsorption strength for lithium polysulfides and better catalytic properties for their conversion. As a result, the lithium-sulfur batteries with (CuCo)Se2-NCNT achieve a high specific capacity of 1051.06 mAh g-1 at 1C and an enhanced rate property with a specific capacity of 838.27 mAh g-1 at 4C. The work provides meaningful insights into the design of bimetallic compounds as catalysts for lithium-sulfur batteries.

Attenuating the Polysulfide Shuttle Mechanism by Separator Coating

Lithium-sulfur batteries have a high energy density but lack cycle stability to reach market maturity. This is mainly due to the polysulfide shuttle mechanism, i. e., the leaching of active material from the cathode into the electrolyte and subsequent side reactions. We demonstrate how to attenuate the polysulfide shuttle by magnetron sputtering molybdenum oxysulfide, manganese oxide, and chromium oxide onto microporous polypropylene separators. The morphology of the amorphous coatings was analyzed by SEM and XRD. Electrochemical cyclization quantified how these coatings improved Coulombic efficiency and cycle stability. These tests were conducted in half cells. We compare the different performances of the different coatings with the known chemical and adsorption properties of the respective coating materials.

Heterogenization-Activated Zinc Telluride via Rectifying Interfacial Contact to Afford Synergistic Confinement-Adsorption-Catalysis for High-Performance Lithium-Sulfur Batteries

The notorious shuttle effect and sluggish conversion kinetics of intermediate polysulfides (Li2S4, Li2S6, Li2S8) are severely hindered the large-scale development of Lithium-sulfur (Li-S) batteries. Rectifying interface effect has been a solution to regulate the electron distribution of catalysts via interfacial charge exchange. Herein, a ZnTe-ZnO heterojunction encapsulated in nitrogen-doped hierarchical porous carbon (ZnTe-O@NC) derived from metal-organic framework is fabricated. Theoretical calculations and experiments prove that the built-in electric field constructed at ZnTe-ZnO heterojunction via the rectifying interface contact, thus promoting the charge transfer as well as enhancing adsorption and conversion kinetics toward polysulfides, thereby stimulating the catalytic activity of the ZnTe. Meanwhile, the nitrogen-doped hierarchical porous carbon acts as confinement substrate also enables fast electrons/ions transport, combining with ZnTe-ZnO heterojunction realize a synergistic confinement-adsorption-catalysis toward polysulfides. As a result, the Li-S batteries with S/ZnTe-O@NC electrodes exhibit an impressive rate capability (639.7 mAh g-1 at 3 C) and cycling performance (70% capacity retention at 1 C over 500 cycles). Even with a high sulfur loading, it still delivers a superior electrochemical performance. This work provides a novel perspective on designing highly catalytic materials to achieve synergistic confinement-adsorption-catalysis for high-performance Li-S batteries.

Molecular Intercalation Enables Phase Transition of MoSe2 for Durable Na-Ion Storage

1T-MoSe2 is recognized as a promising anode material for sodium-ion batteries, thanks to its excellent electrical conductivity and large interlayer distance. However, its inherent thermodynamic instability often presents unparalleled challenges in phase control and stabilization. Here, a molecular intercalation strategy is developed to synthesize thermally stable 1T-rich MoSe2, covalently bonded to an intercalated carbon layer (1TR/2H-MoSe2@C). Density functional theory calculations uncover that the introduced ethylene glycol molecules not only serve as electron donors, inducing a reorganization of Mo 4d orbitals, but also as sacrificial guest materials that generate a conductive carbon layer. Furthermore, the C─Se/C─O─Mo bonds encourage strong interfacial electronic coupling, and the carbon layer prevents the restacking of MoSe2, regulating the maximum 1T phase to an impressive 80.3%. Consequently, the 1TR/2H-MoSe2@C exhibits an extraordinary rate capacity of 326 mAh g-1 at 5 A g-1 and maintains a long-term cycle stability up to 1500 cycles, with a capacity of 365 mAh g-1 at 2 A g-1. Additionally, the full cell delivers an appealing energy output of 194 Wh kg-1 at 208 W kg-1, with a capacity retention of 87.3% over 200 cycles. These findings contribute valuable insights toward the development of innovative transition metal dichalcogenides for next-generation energy storage technologies.

Recent Progress on Copper-Based Bimetallic Heterojunction Catalysts for CO2 Electrocatalysis: Unlocking the Mystery of Product Selectivity

Copper-based bimetallic heterojunction catalysts facilitate the deep electrochemical reduction of CO2 (eCO2RR) to produce high-value-added organic compounds, which hold significant promise. Understanding the influence of copper interactions with other metals on the adsorption strength of various intermediates is crucial as it directly impacts the reaction selectivity. In this review, an overview of the formation mechanism of various catalytic products in eCO2RR is provided and highlight the uniqueness of copper-based catalysts. By considering the different metals' adsorption tendencies toward various reaction intermediates, metals are classified, including copper, into four categories. The significance and advantages of constructing bimetallic heterojunction catalysts are then discussed and delve into the research findings and current development status of different types of copper-based bimetallic heterojunction catalysts. Finally, insights are offered into the design strategies for future high-performance electrocatalysts, aiming to contribute to the development of eCO2RR to multi-carbon fuels with high selectivity.

Oxygen Vacancy-Enhanced Ni3N-CeO2/NF Nanoparticle Catalysts for Efficient and Stable Electrolytic Water Splitting

Highly efficient and cost-effective electrocatalysts are of critical significance in the domain of water electrolysis. In this study, a Ni3N-CeO2/NF heterostructure is synthesized through a facile hydrothermal technique followed by a subsequent nitridation process. This catalyst is endowed with an abundance of oxygen vacancies, thereby conferring a richer array of active sites. Therefore, the catalyst demonstrates a markedly low overpotential of 350 mV for the Oxygen Evolution Reaction (OER) at 50 mA cm-2 and a low overpotential of 42 mV for the Hydrogen Evolution Reaction (HER) at 10 mA cm-2. Serving as a dual-function electrode, this electrocatalyst is employed in overall water splitting in alkaline environments, demonstrating impressive efficiency at a cell voltage of 1.52 V of 10 mA cm-2. The in situ Raman spectroscopic analysis demonstrates that cerium dioxide (CeO2) facilitates the rapid reconfiguration of oxygen vacancy-enriched nickel oxyhydroxide (NiOOH), thereby enhancing the OER performance. This investigation elucidates the catalytic role of CeO2 in augmenting the OER efficiency of nickel nitride (Ni3N) for water electrolysis, offering valuable insights for the design of high-performance bifunctional catalysts tailored for water splitting applications.