New Conceptual Catalyst on Spatial High-Entropy Alloy Heterostructures for High-Performance Li-O2 Batteries.

High-entropy alloys (HEAs) are attracting increased attention as an alternative to noble metals for various catalytic reactions. However, it is of great challenge and fundamental importance to develop spatial HEA heterostructures to manipulate d-band center of interfacial metal atoms and modulate electron-distribution to enhance electrocatalytic activity of HEA catalysts. Herein, an efficient strategy is demonstrated to construct unique well-designed HEAs spatial heterostructure electrocatalyst (HEA@Pt) as bifunctional cathode to accelerate oxygen reduction and evolution reaction (ORR/OER) kinetics for Li-O2 batteries, where uniform Pt dendrites grow on PtRuFeCoNi HEA at a low angle boundary. Such atomically connected HEA spatial interfaces engender efficient electrons from HEA to Pt due to discrepancy of work functions, modulating electron distribution for fast interfacial electron transfer, and abundant active sites. Theoretical calculations reveal that electron redistribution manipulates d-band center of interfacial metal atoms, allowing appropriate adsorption energy of oxygen species to lower ORR/OER reaction barriers. Hence, Li-O2 battery based on HEA@Pt electrocatalyst delivers a minimal polarization potential (0.37 V) and long-term cyclability (210 cycles) under a cut-off capacity of 1000 mAh g-1 , surpassing most previously reported noble metal-based catalysts. This work provides significant insights on electron-modulation and d-band center optimization for advanced electrocatalysts.

Electron Acceptor Molecule Doping Induced π-π Interaction to Promote Charge Transport Kinetics for Efficient and Stable 2D/3D Perovskite Solar Cells.

Although the incorporation of 2D perovskite into 3D perovskite can greatly enhance intrinsic stability, power conversion efficiency (PCE) of 2D/3D perovskite is still inferior to its 3D counterpart due to poor carrier transport kinetics resulted from the quantum and dielectric confinement of 2D component. To overcome this issue, the electron acceptor molecule 1,2,4,5-tetracyanobenzene (TCNB) was introduced to trigger intermolecular π-π interaction in 2D perovskite along with the electronic doping of 2D/3D perovskite to improve charge transfer efficiency. By virtue of high electron affinity, TCNB can undergo electron transfer reaction and subsequently establish π-π interaction with 1-naphthalenemethylammonium (NMA) cations, greatly strengthening lattice rigidity and reducing exciton binding energy. Transmission electron microscopy results demonstrate that 2D phases are mainly distributed at grain boundaries, reducing defect density and weakening nonradiative recombination. Meanwhile, the p-type doping of perovskite by TCNB optimizes energy level alignment at perovskite/hole transport layer interface. Consequently, PCE of champion device is significantly boosted to 24.01 %. The unencapsulated device retains an initial efficiency close to 94 % after exposure to ambient environment for over 1000 h. This work paves a novel path for designing new mixed-dimensional perovskite solar cells with high PCE and superior stability.

Oxide Nanoclusters on Ti3 C2 MXenes to Deactivate Defects for Enhanced Lithium Ion Storage Performance.

The commercialization of MXenes as anodes for lithium-ion batteries is largely impeded by low initial coulombic efficiency (ICE) and unfavorable cycling stability, which are closely associated with defects such as Ti vacancies (VTi ) in Ti3 C2 MXenes. Herein, an effective strategy is developed to deactivate VTi defects by in situ growing Al2 O3 nanoclusters on MXenes to alleviate the irreversible electrolyte decomposition and Li dendrites formation trend induced by defects, improving ICE and cycling stability. Furthermore, it is revealed that excessively lithiophilic VTi defects would impede Li ions diffusion due to their strong adsorption, leading to a locally nonuniform Li flux to these "hot spots," setting scene for the formation of Li dendrites. The Al2 O3 nanoclusters anchored on VTi sites can not only improve Li diffusion kinetics but also promote the homogeneous solid electrolyte interphase formation with small charge transfer resistance, achieving uniform Li deposition in a smaller overpotential without formation of Li dendrites. As expected, Ti3 C2 @Al2 O3 -11 electrode delivers a high ICE of 76.6% and an outstanding specific capacity of 285.5 mAh g-1 after 500 cycles, which is much higher than that of pristine Ti3 C2 sample. This work sheds light on modulating defects for high-performance energy storage materials.

One-Step Route Synthesized Co2 P/Ru/N-Doped Carbon Nanotube Hybrids as Bifunctional Electrocatalysts for High-Performance Li-O2 Batteries.

The large-scale commercial application of lithium-oxygen batteries (LOBs) is overwhelmed by the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) associated with insoluble and insulated Li2 O2 . Herein, an elaborate design on a highly catalytic LOBs cathode constructed by N-doped carbon nanotubes (CNT) with in situ encapsulated Co2 P and Ru nanoparticles is reported. The homogeneously dispersed Co2 P and Ru catalysts can effectively modulate the formation and decomposition behavior of Li2 O2 during discharge/charge processes, ameliorating the electronically insulating property of Li2 O2 and constructing a homogenous low-impedance Li2 O2 /catalyst interface. Compared with Co/CNT and Ru/CNT electrodes, the Co2 P/Ru/CNT electrode delivers much higher oxygen reduction triggering onset potential and higher ORR and OER peak current and integral areas, showing greatly improved ORR/OER kinetics due to the synergistic effects of Co2 P and Ru. Li-O2 cells based on the Ru/Co2 P/CNT electrode demonstrate improved ORR/OER overpotential of 0.75 V, excellent rate capability of 12 800 mAh g-1 at 1 A g-1 , and superior cycle stability for more than 185 cycles under a restricted capacity of 1000 mAh g-1 at 100 mA g-1 . This work paves an exciting avenue for the design and construction of bifunctional catalytic cathodes by coupling metal phosphides with other active components in LOBs.

Mesoporous Hollow Sb/ZnS@C Core-Shell Heterostructures as Anodes for High-Performance Sodium-Ion Batteries.

Combining the advantage of metal, metal sulfide, and carbon, mesoporous hollow core-shell Sb/ZnS@C hybrid heterostructures composed of Sb/ZnS inner core and carbon outer shell are rationally designed based on a robust template of ZnS nanosphere, as anodes for high-performance sodium-ion batteries (SIBs). A partial cation exchange reaction based on the solubility difference between Sb2 S3 and ZnS can transform mesoporous ZnS to Sb2 S3 /ZnS heterostructure. To get a stable structure, a thin contiguous resorcinol-formaldehyde (RF) layer is introduced on the surface of Sb2 S3 /ZnS heterostructure. The effectively protective carbon layer from RF can be designed as the reducing agent to convert Sb2 S3 to metallic Sb to obtain core-shell Sb/ZnS@C hybrid heterostructures. Simultaneously, the carbon outer shell is beneficial to the charge transfer kinetics, and can maintain the structure stability during the repeated sodiation/desodiation process. Owing to its unique stable architecture and synergistic effects between the components, the core-shell porous Sb/ZnS@C hybrid heterostructure SIB anode shows a high reversible capacity, good rate capability, and excellent cycling stability by turning the optimized voltage range. This novel strategy to prepare carbon-layer-protected metal/metal sulfide core-shell heterostructure can be further extended to design other novel nanostructured systems for high-performance energy storage devices.

Chemical Immobilization Effect on Lithium Polysulfides for Lithium-Sulfur Batteries.

Despite great progress in lithium-sulfur batteries (LSBs), great obstacles still exist to achieve high loading content of sulfur and avoid the loss of active materials due to the dissolution of the intermediate polysulfide products in the electrolyte. Relationships between the intrinsic properties of nanostructured hosts and electrochemical performance of LSBs, especially, the chemical interaction effects on immobilizing polysulfides for LSB cathodes, are discussed in this Review. Moreover, the principle of rational microstructure design for LSB cathode materials with strong chemical interaction adsorbent effects on polysulfides, such as metallic compounds, metal particles, organic polymers, and heteroatom-doped carbon, is mainly described. According to the chemical immobilizing mechanism of polysulfide on LSB cathodes, three kinds of chemical immobilizing effects, including the strong chemical affinity between polar host and polar polysulfides, the chemical bonding effect between sulfur and the special function groups/atoms, and the catalytic effect on electrochemical reaction kinetics, are thoroughly reviewed. To improve the electrochemical performance and long cycling life-cycle stability of LSBs, possible solutions and strategies with respect to the rational design of the microstructure of LSB cathodes are comprehensively analyzed.

First principles study of electronic transport properties in novel FeB2 flake-based nanodevices.

First-principles calculations can provide theoretical support for the promising applications of innovative two-probe devices based on FeB2 flakes at different temperatures. Results indicate that these FeB2-based devices not only exhibit a prominent transport capacity and a predictable strong current, but also possess outstanding electrical conductivity compared with many flake-based devices. Devices with FeB2 flakes at temperatures not above 1000 K have advantageous transmission and low-voltage current because of the delocalization of electronic states, essentially resulting from their undeformed flake structures. Importantly, Fe atoms are pivotal in the electron transport of FeB2-based devices. The edge effect of the flakes is also analyzed. These new-type FeB2 flakes can realize substantial value in nanoscale functional devices.

Ni2 P@Carbon Core-Shell Nanoparticle-Arched 3D Interconnected Graphene Aerogel Architectures as Anodes for High-Performance Sodium-Ion Batteries.

To alleviate large volume change and improve poor electrochemical reaction kinetics of metal phosphide anode for sodium-ion batteries, for the first time, an unique Ni2 P@carbon/graphene aerogel (GA) 3D interconnected porous architecture is synthesized through a solvothermal reaction and in situ phosphorization process, where core-shell Ni2 P@C nanoparticles are homogenously embedded in GA nanosheets. The synergistic effect between components endows Ni2 P@C/GA electrode with high structural stability and electrochemical activity, leading to excellent electrochemical performance, retaining a specific capacity of 124.5 mA h g-1 at a current density of 1 A g-1 over 2000 cycles. The robust 3D GA matrix with abundant open pores and large surface area can provide unblocked channels for electrolyte storage and Na+ transfer and make fully close contact between the electrode and electrolyte. The carbon layers and 3D GA together build a 3D conductive matrix, which not only tolerates the volume expansion as well as prevents the aggregation and pulverization of Ni2 P nanoparticles during Na+ insertion/extraction processes, but also provides a 3D conductive highway for rapid charge transfer processes. The present strategy for phosphides via in situ phosphization route and coupling phosphides with 3D GA can be extended to other novel electrodes for high-performance energy storage devices.

Amperometric hydrogen peroxide and glucose biosensor based on NiFe2/ordered mesoporous carbon nanocomposites.

Nanocomposites of NiFex embedded in ordered mesoporous carbon (OMC) (x = 0, 1, 2) were prepared by a wet impregnation and hydrogen reduction process and were used to construct electrochemical biosensors for the amperometric detection of hydrogen peroxide (H2O2) or glucose. The NiFe2/OMC nanocomposites were demonstrated to have a large surface area, suitable mesoporous channels, many edge-plane-like defective sites, and a good distribution of alloyed nanoparticles. The NiFe2/OMC and Nafion modified glass carbon electrode (GCE) exhibited excellent electrocatalytic activities toward the reduction of H2O2 as well. By utilizing it as a bioplatform, GOx (glucose oxidase) cross-linked with Nafion was immobilized on the surface of the electrode for the construction of an amperometric glucose biosensor. Our results indicated that the amperometric hydrogen peroxide biosensor (NiFe2/OMC + Nafion + GCE) showed good analytical performances in term of a high sensitivity of 4.29 µA mM(-1) cm(-2), wide linearity from 6.2 to 42,710 µM and a low detection limit of 0.24 µM at a signal-to-noise ratio of 3 (S/N = 3). This biosensor exhibited excellent selectivity, high stability and negligible interference for the detection of H2O2. In addition, the immobilized enzyme on NiFe2/OMC + Nafion + GCE, retaining its bioactivity, exhibited a reversible two-proton and two-electron transfer reaction, a fast heterogeneous electron transfer rate and an effective Michaelis-Menten constant (K) (3.18 mM). The GOx + NiFe2/OMC + Nafion + GCE could be used to detect glucose based on the oxidation of glucose catalyzed by GOx and exhibited a wide detection range of 48.6-12,500 µM with a high sensitivity of 6.9 µA mM(-1) cm(-2) and a low detection limit of 2.7 µM (S/N = 3). The enzymic biosensor maintained a high selectivity and stability features, and shows great promise for application in the detection of glucose.

Nitrogen doped TiO2-Cu(x)O core-shell mesoporous spherical hybrids for high-performance dye-sensitized solar cells.

We report on high-performance dye-sensitized solar cells (DSSCs) based on nitrogen doped anatase TiO2-CuxO core-shell mesoporous hybrids synthesized through a facile and controlled combined sol-gel and hydrothermal process in the presence of hexadecylamine as the structure-directing agent. The matching of band edges between CuxO and TiO2 to form a semiconductor heterojunction plays an important role in effective separation of light induced electrons and holes, providing a promising photoanode for DSSCs because of its wide absorption spectrum, high electron injection efficiency, and fast electron transference. DSSCs based on the mesoporous TiO2-CuxO core-shell hybrids show a high short-circuit current density of 9.60 mA cm(-2) and a conversion efficiency of 3.86% under one sun illumination. While DSSCs based on the N-doped mesoporous TiO2-CuxO hybrids exhibit the higher short-circuit current density of 13.24 mA cm(-2) and a conversion efficiency of 4.57% under one sun illumination. In comparison with un-doped TiO2-CuxO hybrids, the doping of nitrogen into the lattice of TiO2 can extend the light absorption in the ultraviolet range to the visible light region and effectively decrease the recombination rate of photo-generated electrons and holes. The presented N-doped mesoporous TiO2-CuxO hybrids as photoanodes could find potential applications for high performance DSSCs.

Molecule-Level Multiscale Design of Nonflammable Gel Polymer Electrolyte to Build Stable SEI/CEI for Lithium Metal Battery.

The risk of flammability is an unavoidable issue for gel polymer electrolytes (GPEs). Usually, flame-retardant solvents are necessary to be used, but most of them would react with anode/cathode easily and cause serious interfacial instability, which is a big challenge for design and application of nonflammable GPEs. Here, a nonflammable GPE (SGPE) is developed by in situ polymerizing trifluoroethyl methacrylate (TFMA) monomers with flame-retardant triethyl phosphate (TEP) solvents and LiTFSI-LiDFOB dual lithium salts. TEP is strongly anchored to PTFMA matrix via polarity interaction between -P = O and -CH2CF3. It reduces free TEP molecules, which obviously mitigates interfacial reactions, and enhances flame-retardant performance of TEP surprisingly. Anchored TEP molecules are also inhibited in solvation of Li+, leading to anion-dominated solvation sheath, which creates inorganic-rich solid electrolyte interface/cathode electrolyte interface layers. Such coordination structure changes Li+ transport from sluggish vehicular to fast structural transport, raising ionic conductivity to 1.03 mS cm-1 and transfer number to 0.41 at 30 °C. The Li|SGPE|Li cell presents highly reversible Li stripping/plating performance for over 1000 h at 0.1 mA cm-2, and 4.2 V LiCoO2|SGPE|Li battery delivers high average specific capacity > 120 mAh g-1 over 200 cycles. This study paves a new way to make nonflammable GPE that is compatible with Li metal anode.

Revealing the Effect of the Microstructure on Potassium Storage Behavior in a Two-Dimensional Mesoporous Carbon Anode.

Hard carbon is considered as the most promising anode material for potassium-ion energy storage devices. Substantial progress has been made in exploring advanced hard carbons to solve the issues of sluggish kinetics and large volume changes caused by the large radius of K+. However, the relationship between their complicated microstructures and the K+ charge storage behavior is still not fully explored. Herein, a series of two-dimensional mesoporous carbon microcoins (2D-MCMs) with tunable microstructures in heteroatom content and graphitization degree are synthesized by a facile hard-template method and follow a temperature-controllable annealing process. It is found that high heteroatom content makes for surface-driven K+ storage behavior, which increases the capacity-contribution ratio from a high potential region, while a high graphitization degree makes for K+ intercalation behavior, which increases the capacity-contribution ratio from a low potential region. Electrochemical results from a three-electrode Swagelok cell demonstrate that a 2D-MCM anode with more capacity contribution from a low working region allows the porous carbon cathode to be operated in a much wider electrochemical window, thus storing more charge. As a result, potassium-ion capacitors based on the optimized 2D-MCM anode deliver a high energy density of 113 Wh kg-1 and an exhilarating power density of 51,000 W kg-1.

Core-shell structured α-Fe2O3@TiO2 nanocomposites with improved photocatalytic activity in the visible light region.

The core-shell structured Fe2O3@TiO2 nanocomposites prepared via a heteroepitaxial growth route using the Fe2O3 spindle as a hard template display improved photocatalytic degradation activity for Rhodamine B dye under visible light irradiation. The ratio of α-Fe2O3 : TiO2 in the α-Fe2O3@TiO2 core-shell nanocomposites can be tuned by etching the α-Fe2O3 core via controlling the concentration of HCl and etching time. An appropriate concentration of the Fe2O3 core could effectively induce a transition of the optical response from the UV to the visible region and decrease the recombination rate of photogenerated electrons and the holes of the core-shell structured catalyst, greatly contributing to the enhancement of visible light response and visible light photocatalytic activity of the Fe2O3@TiO2 catalysts. It is revealed that the optical response and photocatalytic performance of the core-shell α-Fe2O3@TiO2 nanocomposites can be tuned by adjusting the molar ratio of Fe2O3 : TiO2 of the α-Fe2O3@TiO2 nanocomposites. The α-Fe2O3@TiO2 core-shell nanocomposite with an optimal molar ratio of 7% for Fe2O3 : TiO2 exhibits the best photocatalytic performance under visible light irradiation. It is shown that the Fe2O3/TiO2 heterojunction structure is responsible for the efficient visible-light photocatalytic activity. As the concentration of Fe2O3 is high, Fe(3+) ions will act as recombination centres of the photogenerated electrons and holes. The present core-shell Fe2O3@TiO2 nanoparticles displaying enhanced photodegradation activity could find potential applications as photocatalysts for the abatement of various organic pollutants.

MoO2-ordered mesoporous carbon hybrids as anode materials with highly improved rate capability and reversible capacity for lithium-ion battery.

A novel hybrid of MoO2-ordered mesoporous carbon (MoO2-OMC) was prepared through a two-step solvothermal chemical reaction route. The electrochemical performances of the mesoporous MoO2-OMC hybrids were examined using galvanostatical charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques. The MoO2-OMC hybrid exhibits significantly improved electrochemical performance of high reversible capacity, high-rate capability, and excellent cycling performance as an anode electrode material for Li ion batteries. It is revealed that the MoO2-OMC hybrid could deliver the first discharge capacity of 1641.8 mA h g(-1) with an initial Coulombic efficiency of 63.6%, and a reversible capacity as high as 1049.1 mA h g(-1) even after 50 cycles at a current density of 100 mA g(-1), much higher than the theoretical capacity of MoO2 (838 mA h g(-1)) and OMC materials. The MoO2-OMC hybrid demonstrates an excellent high rate capability with capacity of ∼600 mA h g(-1) even at a charge current density of 1600 mA g(-1) after 50 cycles, which is approximately 11.1 times higher than that of the OMC (54 mA h g(-1)) materials. The improved rate capability and reversible capacity of the MoO2-OMC hybrid are attributed to a synergistic reaction between the MoO2 nanoparticles and mesoporous OMC matrices. It is noted that the electrochemical performance of the MoO2-OMC hybrid is evidently much better than the previous MoO2-based hybrids.

Competitive Li+ Coordination in Ionogel Electrolytes for Enhanced Li-Ion Transport Kinetics.

Developing ionogel electrolytes based on ionic liquid instead of volatile liquid in gel polymer electrolytes is regarded to be effective to diminish safety concerns in terms of overheating and fire. Herein, a zwitterion-based copolymer matrix based on the copolymerization of trimethylolpropane ethoxylate triacrylate (ETPTA) and 2-methacryloyloxyethylphosphorylcholine (MPC, one typical zwitterion) is developed. It is shown that introducing zwitterions into ionogel electrolytes can effectively optimize local lithium-ion (Li+ ) coordination environment to improve Li+ transport kinetics. The interactions between Li+ and bis(trifluoromethanesulfonyl)imide (TFSI- )/MPC lead to the formation of Li+ coordination shell jointly occupied by MPC and TFSI- . Benefiting from the competitive Li+ attraction of TFSI- and MPC, the energy barrier of Li+ desolvation is sharply decreased and thus the room-temperature ionic conductivity can reach a value of 4.4 × 10-4 S cm-1 . Besides, the coulombic interaction between TFSI- and MPC can greatly decrease the reduction stability of TFSI- , boosting in situ derivation of LiF-enriched solid electrolyte interface  layer on lithium metal surface. As expected, the assembled Li||LiFePO4 cells deliver a high reversible discharge capacity of 139 mAh g-1 at 0.5 C and good cycling stability. Besides, the pouch cells exhibit a steady open-circuit voltage and can operate normally under abuse testing (fold, cut), showing its outstanding safety performance.

Intrinsic Dipole Arrangement to Coordinate Energy Levels for Efficient and Stable Perovskite Solar Cells.

Despite great progress in perovskite photovoltaics, it should be noted that the intrinsic disorder dipolar cations in organic-inorganic hybrid perovskites exert negative effects on the energy band structure as well as the carrier separation and transfer dynamics. However, oriented polarization achieved by applying an external electric field may cause irreversible damage to perovskites. Herein, a unique and efficient strategy is developed to modulate the intrinsic dipole arrangement in perovskite films for high-performance and stable perovskite solar cells (PSCs). The spontaneous reorientation of dipolar cation methylamine is triggered by a polar molecule, constructing a vertical polarization during crystallization regulation. The oriented dipole determines a gradient energy-level arrangement in PSCs and more favorable energetics at interfaces, effectively enhancing the built-in electric field and suppressing the nonradiative recombination. Besides, the dipole reorientation induces a local dielectric environment to remarkably reduce exciton binding energy, leading to an ultralong carrier diffusion length of up to 1708 nm. Accordingly, the n-i-p PSCs achieve a significant increase in power conversion efficiency, reaching 24.63% with negligible hysteresis and exhibiting outstanding stabilities. This strategy also provides a facile route to eliminate the mismatched energetics and enhance carrier dynamics for other novel photovoltaic devices.

Robust All-Solid-State Lithium Metal Batteries Enabled by a Composite Lithium Anode with Improved Bulk Li Diffusion Kinetics Properties.

All-solid-state batteries (ASSBs) with a Li metal anode are expected to be one of the most promising energy storage systems to achieve high energy density. However, the interfacial instability between the Li metal anode and solid-state electrolyte (SSE) limits the rate capability and cycling stability of ASSBs. The main issue is the formation of voids at the Li/SSE interface during Li stripping due to the slow diffusion of Li within the bulk Li metal, then increasing internal cell resistance and inducing the formation of lithium dendrites. To address these issues, a composite Li anode (LAO) composed by Li-Ag alloy and Li2O is constructed by mixing the stoichiometric metal Li and Ag2O directly. LAO anode is capable of improving bulk Li diffusion kinetics and inhibiting the formation of interfacial voids effectively, achieving a high critical current density over 1.5 mA cm-2 and long stable cycling over 1000 h at 1 mA cm-2. The ASSBs, employing LAO as the anode, Li6PS5Cl as the SSE, and LiCoO2 as the cathode, exhibit superior rate capability and stable cycling over 4000 cycles at 5 C. Moreover, ASSBs can operate stably with a high LiCoO2 loading of 17.8 mg cm-2 for more than 100 cycles at 0.2 C.

Hexaindium Heptasulfide/Nitrogen and Sulfur Co-Doped Carbon Hollow Microspindles with Ultrahigh-Rate Sodium Storage through Stable Conversion and Alloying Reactions.

Group IIIA-VA metal sulfides (GMSs) have attracted increasing attention because of their unique Na-storage mechanisms through combined conversion and alloying reactions, thus delivering large theoretical capacities and low working potentials. However, Na+ diffusion within GMSs anodes leads to severe volume change, generally representing a fundamental limitation to rate capability and cycling stability. Here, monodispersed In6 S7 /nitrogen and sulfur co-doped carbon hollow microspindles (In6 S7 /NSC HMS) are produced by morphology-preserved thermal sulfurization of spindle-like and porous indium-based metal organic frameworks. The resulting In6 S7 /NSC HMS anode exhibits theoretical-value-close specific capacity (546.2 mAh g-1 at 0.1 A g-1 ), ultrahigh rate capability (267.5 mAh g-1 at 30.0 A g-1 ), high initial coulombic efficiency (≈93.5%), and ≈92.6% capacity retention after 4000 cycles. This kinetically favored In6 S7 /NSC HMS anode fills up the kinetics gap with a capacitive porous carbon cathode, enabling a sodium-ion capacitor to deliver an ultrahigh energy density of 136.3 Wh kg-1 and a maximum power density of 47.5 kW kg-1 . The in situ/ex situ analytical techniques and theoretical calculation both show that the robust and fast Na+ charge storage of In6 S7 /NSC HMS arises from the multi-electron redox mechanism, buffered volume expansion, negligible morphological change, and surface-controlled solid-state Na+ transport.

Simultaneous removal of arsenite and arsenate from mining wastewater using ZIF-8 embedded with iron nanoparticles.

Arsenic contamination is an increasing global environmental problem, especially in mining industry wastewater where both arsenite (As(III)) and arsenate (As(V)) have been routinely detected. In this paper, a novel porous metal-organic framework material (ZIF-8) was composited with iron nanoparticles (FeNPs) to form a functional material (ZIF-8@FeNPs) for the simultaneous removal of As(III)/(V) from wastewater. The material effectively removed both As(III) and As(V) with removal efficiencies of 99.9 and 71.2%, respectively. Advanced characterization techniques including X-ray photoelectron spectroscopy (XPS) and Fourier infrared (FTIR) indicated that removal of As(III) and As(V) involved complex formation. Adsorption kinetics followed a pseudo-second order kinetics indicating adsorption involved chemisorption. After four cycles of reuse the he removal rate of As species was still relatively high at > 60% When ZIF-8@FeNPs were used to remove As from real wastewater from acid mines the removal efficiency was 94.27%. Finally, a As(III) and As(V) removal mechanism was proposed.