Synergistic interface and structural engineering for high initial coulombic efficiency and stable sodium storage in metal sulfides.

Transition metal sulfides (TMS) have gained significant attention as potential anode materials for sodium ion batteries (SIBs) due to their high theoretical capacity and abundance in nature. Nevertheless, their practical use has been impeded by challenges such as large volume changes, unstable solid electrolyte interphase (SEI), and low initial coulombic efficiency (ICE). To address these issues and achieve both long-term cycling stability and high ICE simultaneously, we present a novel approach involving surface engineering, termed as the "dual-polar confinement" strategy, combined with interface engineering to enhance the electrochemical performance of TMS. In this approach, CoS crystals are meticulously coated with polar TiO2 and embedded within a polar S-doped carbon matrix, forming a composite electrode denoted as CoS/TiO2-SC. Significantly, an ether-based electrolyte with chemical stability and optimized solvation properties synergistically interacts with the Co-S-C bonds to create a stable, ultra-thin SEI. This concerted effect results in a notably high ICE, reaching approximately 96%. Advanced characterization and theoretical simulations confirm that the uniform surface modification effectively facilitates sodium ion transport kinetics, restrains electrode pulverization, and concurrently enhances interaction with the ether-based electrolyte to establish a robust SEI. Consequently, the CoS/TiO2-SC electrode exhibits high reversible capacity, superior rate capability, and outstanding cycling stability.

Ultrastable Electrolytic Zn-I2 Batteries Based on Nanocarbon Wrapped by Highly Efficient Single-Atom Fe-NC Iodine Catalysts.

Aqueous Zn-iodine (Zn-I2) conversion batteries with iodine redox chemistry suffers the severe polyiodide shuttling and sluggish redox kinetics, which impede the battery lifespan and rate capability. Herein, an ultrastable Zn-I2 battery is introduced based on single-atom Fe-N-C encapsulated high-surface-area carbon (HC@FeNC) as the core-shell cathode materials, which accelerate the I-/I3 -/I° conversion significantly. The robust chemical-physical interaction between polyiodides and Fe-N4 sites tightly binds the polyiodide ions and suppresses the polyiodide shuttling, thereby significantly enhancing the coulombic efficiency. As a result, the core-shell HC@FeNC cathode endows the electrolytic Zn-I2 battery with an excellent capacity, remarkable rate capability, and an ultralong lifespan over 60 000 cycles. More importantly, a practical 253 Wh kg-1 pouch cell shows good capacity retention of 84% after 100 cycles, underscoring its considerable potential for commercial Zn-I2 batteries.

A Highly Reversible Sn-Air Battery Possessing the Ultra-Low Charging Potential with the Assistance of Light.

Aqueous Sn-air batteries are attracting a great deal of interest in recent years due to the ultra-high safety, low cost, dendrite-free and highly reversible Sn anode. However, the slurry oxygen reduction/evolution reaction (ORR/OER) kinetics on the air cathodes seriously affect the Sn-air battery performances. Although various advanced catalysts have been developed, the charge overpotentials (~1000 mV) of these Sn-air batteries are still not satisfactory. Herein, iron oxide (Fe2O3) modified titanium dioxide (TiO2) nanorods with heterogeneous structure are firstly synthesized on Ti mesh (Fe2O3@TiO2/Ti), and the obtained Fe2O3@TiO2/Ti is further applied as catalytic electrodes for Sn-air batteries. The core-shell heterogeneous structure of Fe2O3@TiO2/Ti can effectively facilitate the conversion of electrochemical intermediates and separation of photo-excited electrons and holes to active oxygen-related reaction processes. DFT and experimental results also confirm that Fe2O3@TiO2/Ti can not only act as the electrocatalysts to improve ORR/OER properties, but also exhibit the superior photo-catalytic activity to promote charge kinetics. Hence, the Fe2O3@TiO2/Ti-based Sn-air batteries show ultra-low overpotential of ~40 mV, excellent rate capability and good cycling stability under light irradiation. This work will shed light on rational photo-assisted catalytic cathode design for new-type metal-air batteries.

Natural flocculant chitosan inhibits short-chain fatty acid production in anaerobic fermentation of waste activated sludge.

Chitosan (CTS) serves as an excellent natural flocculant in wastewater purification and sludge conditioning, but its potential impact on anaerobic fermentation of waste-activated sludge is unclear. The current study investigated the role of CTS in short-chain fatty acids (SCFAs) generation via sludge alkaline anaerobic fermentation. The results showed a drastic reduction in SCFA production with CTS, showing a maximum inhibition of 33 % at 6 mg/g of total suspended solids. CTS hindered sludge solubilization through flocculation, and acted as a humus precursor, promoting humus formation, and consequently reduced the amount of available substrates. Further, CTS promoted free ammonia production, posing a challenge to enzymes and cell viability. Additionally, CTS increased the population of Rikenellaceae sp. and weakened the dominance of hydrolyzing and acidifying bacteria. This study deepens the understanding of the potential impact of CTS on anaerobic fermentation and provides a theoretical basis for reducing the risk of polymeric flocculants.

Insight into Multiple Intermolecular Coordination of Composite Solid Electrolytes via Cryo-Electron Microscopy for High-Voltage All-Solid-State Lithium Metal Batteries.

Polymer/ceramic-based composite solid electrolytes (CSE) are promising candidates for all-solid-state lithium metal batteries (SLBs), benefiting from the combined mechanical robustness of polymeric electrolytes and the high ionic conductivity of ceramic electrolytes. However, the interfacial instability and poorly understood interphases of CSE hinder their application in high-voltage SLBs. Herein, a simple but effective CSE that stabilizes high-voltage SLBs by forming multiple intermolecular coordination interactions between polyester and ceramic electrolytes is discovered. The multiple coordination between the carbonyl groups in poly(ε-caprolactone) and the fluorosulfonyl groups in anions with Li6.5La3Zr1.5Ta0.5O12 nanoparticles is directly visualized by cryogenic transmission electron microscopy and further confirmed by theoretical calculation. Importantly, the multiple coordination in CSE not only prevents the continuous decomposition of polymer skeleton by shielding the vulnerable carbonyl sites but also establishes stable inorganic-rich interphases through preferential decomposition of anions. The stable CSE and its inorganic-rich interphases enable Li||Li symmetric cells with an exceptional lifespan of over 4800 h without dendritic shorting at 0.1 mA cm-2. Moreover, the high-voltage SLB with LiNi0.5Co0.2Mn0.3O2 cathode displays excellent cycling stability over 1100 cycles at a 1C charge/discharge rate. This work reveals the underlying mechanism behind the excellent stability of coordinating composite electrolytes and interfaces in high-voltage SLBs.

Ni-derived electronic/ionic engineering on NiSe/Ni@C for ultrafast and stable sodium storage.

Atomic-level structure engineering has proven indispensable for fast ion transport kinetics. Herein, a unique framework of NiSe/Ni heterostructure with abundant heterointerface encapsulated hollow carbon spheres, namely NiSe/Ni@C, is synthesized as an anode for SIBs. The NiSe/Ni@C electrode delivers enhanced Na+ storage performance in terms of high specific capacity (490 mA h g-1) and excellent rate capability (546 mA h g-1) at a current of 5.0 A g-1 over 2000 cycles. This study can provide in-depth insights into the interface effect in hybrid structures and shed light on designing energy storage materials.

Li7La3Zr2O12-co-LiNbO3 Surface Modification Improves the Interface Stability between Cathode and Sulfide Solid-State Electrolyte in All-Solid-State Batteries.

With the rapid development of energy storage and electric vehicles, thiophosphate-based all-solid-state batteries (ASSBs) are considered the most promising power source. In order to commercialize ASSBs, the interfacial problem between high-voltage cathode active materials and thiophosphate-based solid-state electrolytes needs to be solved in a simple, effective way. Surface coatings are considered the most promising approach to solving the interfacial problem because surface coatings could prevent direct physical contact between cathode active materials and thiophosphate-based solid-state electrolytes. In this work, Li7La3Zr2O12 (LLZO) and LiNbO3 (LNO) coatings for LiCoO2 (LCO) were fabricated by in-situ interfacial growth of two high-Li+ conductive oxide electrolytes on the LCO surface and tested for thiophosphate-based ASSBs. The coatings were obtained from a two-step traditional sol-gel coatings process, the inner coatings were LNO, and the surface coatings were LLZO. Electrochemical evaluations confirmed that the two-layer coatings are beneficial for ASSBs. ASSBs containing LLZO-co-LNO coatings LiCoO2 (LLZO&LNO@LCO) significantly improved long-term cycling performance and discharge capacity compared with those assembled from uncoated LCO. LLZO&LNO@LCO||Li6PS5Cl (LPSC)||Li-In delivered discharge capacities of 138.8 mAh/g, 101.8 mAh/g, 60.2 mAh/g, and 40.2 mAh/g at 0.05 C, 0.1 C, 0.2 C, and 0.5 C under room temperature, respectively, and better capacity retentions of 98% after 300 cycles at 0.05 C. The results highlighted promising low-cost and scalable cathode material coatings for ASSBs.

Insights into the role of chitosan in hydrogen production by dark fermentation of waste activated sludge.

Chitosan is widely used as a dewatering flocculant, but whether it affects hydrogen production from sludge anaerobic fermentation is unclear. This study aimed to elucidate the role of chitosan in the dark fermentation of waste activated sludge for hydrogen production. The results showed that chitosan had a negative effect on hydrogen production from sludge. Chitosan at 30 g/kg total suspended solids reduced hydrogen accumulation by 56.70 ± 1.22 % from 3.94 ± 0.12 to 1.71 ± 0.10 mL/g volatile suspended solids. Chitosan hindered the solubilization of sludge by flocculation, which reduced the available substrate for anaerobic fermentation. In addition, chitosan interfered with the electron transport system by reducing cytochrome C and caused lipid peroxidation by inducing reactive oxygen species, thereby inhibiting the activity of enzymes involved in anaerobic fermentation. Hydrogen production was reduced because hydrogen-producing processes (i.e., hydrolysis, acidification, and acetification) were inhibited more strongly than hydrogen-consuming processes (i.e., methanogenesis, sulfate reduction, and homoacetogenesis). Furthermore, chitosan enriched the abundance of Spirochaetaceae sp. and Holophagaceae sp., which occupied the survival space of hydrogen-producing microorganisms. This study reveals the potential impact of chitosan on hydrogen production in dark fermentation of sludge and provide direct evidence that chitosan triggers oxidative stress in anaerobic fermentation.

Tuning Photoactive MIL-68(In) by Functionalized Ligands for Boosting Visible-Light Nitrogen Fixation.

In this work, MIL-68(In) functionalized with various ligand substitutions including amine, hydroxyl, bromine, nitro, and methyl groups was prepared, via a one-pot solvothermal reaction for visible-light photocatalytic ammonia synthesis. The diversity of ligands tunes the morphology, geometry, pore environment, and electronic structure of MIL-68(In)-based photocatalysts due to the polarity and intraframework interactions. Amine-inserted MIL-68(In) outperforms its counterparts, presenting a boosted nitrogen photofixation rate of 140.34 µmol gcat-1 h-1 with an apparent quantum efficiency of 5.69% at 420 nm. Further, the size of the batch solvothermal reactor and the amine group content also influence the photocatalytic activity. The combined experimental and theoretical results reveal that amine substituents improve the chemisorption of nitrogen molecules and the conversion of nitrogen into ammonia follows a dual pathway, i.e., a Mars-van Krevelen process and a ligand-to-metal charge transfer mechanism. This work provides a molecular engineering strategy via dual catalysis toward efficient ammonia production.

Elucidating the Synergic Effect in Nanoscale MoS2 /TiO2 Heterointerface for Na-Ion Storage.

Interface engineering in electrode materials is an attractive strategy for enhancing charge storage, enabling fast kinetics, and improving cycling stability for energy storage systems. Nevertheless, the performance improvement is usually ambiguously ascribed to the "synergetic effect", the fundamental understanding toward the effect of the interface at molecular level in composite materials remains elusive. In this work, a well-defined nanoscale MoS2 /TiO2 interface is rationally designed by immobilizing TiO2 nanocrystals on MoS2 nanosheets. The role of heterostructure interface between TiO2 and MoS2 by operando synchrotron X-ray diffraction (sXRD), solid-state nuclear magnetic resonance, and density functional theory calculations is investigated. It is found that the existence of a hetero-interfacial electric field can promote charge transfer kinetics. Based on operando sXRD, it is revealed that the heterostructure follows a solid-solution reaction mechanism with small volume changes during cycling. As such, the electrode demonstrates ultrafast Na+ ions storage of 300 mAh g-1 at 10 A g-1 and excellent reversible capacity of 540 mAh g-1 at 0.2 A g-1 . This work provides significant insights into understanding of heterostructure interface at molecular level, which suggests new strategies for creating unconventional nanocomposite electrode materials for energy storage systems.

Flexible Asymmetric Organic-Inorganic Composite Solid-State Electrolyte Based on PI Membrane for Ambient Temperature Solid-State Lithium Metal Batteries.

Solid-state lithium metal batteries have attracted more and more attention in recent years because of their high safety and energy density, with developments in the new energy industry and energy storage industry. However, solid-state electrolytes are usually symmetric and are not compatible with the cathode and anode at once. In this work, a flexible asymmetric organic-inorganic composite solid-state electrolyte consisting of PI membrane, succinonitrile (SN), LiLaZrTaO(LLZTO), Poly (ethylene glycol) (PEO), and LiTFSI were prepared by solution casting successfully. This lightweight solid electrolyte is stable at a high temperature of 150°C and exhibits a wide electrochemical window of more than 6 V. Furthermore, the high ionic conductivity of the flexible solid electrolyte was 7.3 × 10-7 S/cm. The solid-state batteries assembled with this flexible asymmetric organic-inorganic composite solid electrolyte exhibit excellent performance at ambient temperature. The specific discharge capacity of coin cells using asymmetric organic-inorganic composite solid-state electrolytes was 156.56 mAh/g, 147.25 mAh/g, and 66.55 mAh/g at 0.1, 0.2, and 1C at room temperature. After 100 cycles at 0.2C, the reversible discharging capacity was 96.01 mAh/g, and Coulombic efficiency was 98%. Considering the good performance mentioned above, our designed flexible asymmetric organic-inorganic composite solid electrolyte is appropriate for next-generation solid-state batteries with high cycling stability.

Urbanization and systolic/diastolic blood pressure from a gender perspective: Separating longitudinal from cross-sectional association.

There has been a generally negative view of the impact of urbanization on a rising burden of non-communicable diseases including cardiovascular disease. However, the evidence on the relationship between urbanization and cardiovascular health has remained inconclusive. A comprehensive picture of the relationship is lacking, given an implicit assumption that the longitudinal association between changes in cardiovascular health and an increasingly urbanized environment is similar between less and more urbanized communities, men and women. We used the longitudinal data on adults (18-64 years) from the China Health and Nutrition Survey (1991-2015) and employed within-between random-effects models to disaggregates the longitudinal and cross-sectional associations between urbanization and systolic/diastolic blood pressure (SBP/DBP) and examined heterogeneities in the longitudinal association by average urbanization level and gender. We found that the positive longitudinal association of urbanization with SBP/DBP was stronger in less urbanized than more urbanized communities. The cross-sectional association between urbanization and SBP was negative and significant, although the cross-sectional association between urbanization and DBP was of no statistical significance. Moreover, the positive longitudinal association between urbanization and DBP was stronger among men than women, although the gender heterogeneity in the longitudinal association of urbanization with SBP was not significant.

Building Fast Diffusion Channel by Constructing Metal Sulfide/Metal Selenide Heterostructures for High-Performance Sodium Ion Batteries Anode.

Heterostructure engineering is one of the most promising modification strategies toward improving sluggish kinetics for the anode of sodium ion batteries (SIBs). Herein, we report a systemic investigation on the different types of heterostructure interfaces' effects of discharging products (Na2O, Na2S, Na2Se) on the rate performance. First-principle calculations reveal that the Na2S/Na2Se interface possesses the lowest diffusion energy barrier (0.39 eV) of Na among three kinds of interface structures (Na2O/Na2S, Na2O/Na2Se, and Na2S/Na2Se) due to its smallest recorded interface deformation, similar electronegativity, and lattice constant. The experimental evidence confirms that the metal sulfide/metal selenide (SnS/SnSe2) hierarchical anode exhibits outstanding rate performance, where the normalized capacity at 10 A g-1 compared to 0.1 A g-1 is 45.6%. The proposed design strategy in this work is helpful to design high rate performance anodes for advanced battery systems.

Catalytic Effect on CO2 Electroreduction by Hydroxyl-Terminated Two-Dimensional MXenes.

Electrocatalysis represents a promising method to generate renewable fuels and chemical feedstock from the carbon dioxide reduction reaction (CO2RR). However, traditional electrocatalysts based on transition metals are not efficient enough because of the high overpotential and slow turnover. MXenes, a family of two-dimensional metal carbides and nitrides, have been predicted to be effective in catalyzing CO2RR, but a systematic investigation into their catalytic performance is lacking, especially on hydroxyl (-OH)-terminated MXenes relevant in aqueous reaction conditions. In this work, we utilized first-principles simulations to systematically screen and explore the properties of MXenes in catalyzing CO2RR to CH4 from both aspects of thermodynamics and kinetics. Sc2C(OH)2 was found to be the most promising catalyst with the least negative limiting potential of -0.53 V vs RHE. This was achieved through an alternative reaction pathway, where the adsorbed species are stabilized by capturing H atoms from the MXene's OH termination group. New scaling relations, based on the shared H interaction between intermediates and MXenes, were established. Bader charge analyses reveal that catalysts with less electron migration in the *(H)COOH → *CO elementary step exhibit better CO2RR performance. This study provides new insights regarding the effect of surface functionalization on the catalytic performance of MXenes to guide future materials design.

Altering polythiophene derivative substrates to control the electrodeposition morphology of Au particles toward ultrafine nanoparticles.

A novel strategy for controlling the morphology of AuNPs by altering polythiophene derivative substrates was developed, and the nucleation mechanism of AuNPs on PTs was further explored theoretically. It is found that PTs with longer side chains can induce the electrodeposition of AuNPs with different morphologies and smaller particle sizes.

Elaboration of Aggregated Polysulfide Phases: From Molecules to Large Clusters and Solid Phases.

With the increasing strategies aimed at repressing shuttle problems in the lithium-sulfur battery, dissolved contents of polysulfides are significantly reduced. Except for solid-state Li2S2 and Li2S, aggregated phases of polysulfides remain unexplored, especially in well confined cathode material systems. Here, we report a series of nanosize polysulfide clusters and solid phases from an atomic perspective. The calculated phase diagram and formation energy evolution process demonstrate their stabilities and cohesive tendency. It is interesting to find that Li2S6 can stay in the solid state and contains short S3 chains, further leading to the unique stability and dense structure. Simulated electronic properties indicate reduced band gaps when polysulfides are aggregated, especially for solid phase Li2S6 with a band gap as low as 0.47 eV. Their dissolution behavior and conversion process are also investigated, which provides a more realistic model and gives further suggestions on the future design of the lithium-sulfur battery.

An Aqueous Inorganic Polymer Binder for High Performance Lithium-Sulfur Batteries with Flame-Retardant Properties.

Lithium-sulfur (Li-S) batteries are regarded as promising next-generation high energy density storage devices for both portable electronics and electric vehicles due to their high energy density, low cost, and environmental friendliness. However, there remain some issues yet to be fully addressed with the main challenges stemming from the ionically insulating nature of sulfur and the dissolution of polysulfides in electrolyte with subsequent parasitic reactions leading to low sulfur utilization and poor cycle life. The high flammability of sulfur is another serious safety concern which has hindered its further application. Herein, an aqueous inorganic polymer, ammonium polyphosphate (APP), has been developed as a novel multifunctional binder to address the above issues. The strong binding affinity of the main chain of APP with lithium polysulfides blocks diffusion of polysulfide anions and inhibits their shuttling effect. The coupling of APP with Li ion facilitates ion transfer and promotes the kinetics of the cathode reaction. Moreover, APP can serve as a flame retardant, thus significantly reducing the flammability of the sulfur cathode. In addition, the aqueous characteristic of the binder avoids the use of toxic organic solvents, thus significantly improving safety. As a result, a high rate capacity of 520 mAh g-1 at 4 C and excellent cycling stability of ∼0.038% capacity decay per cycle at 0.5 C for 400 cycles are achieved based on this binder. This work offers a feasible and effective strategy for employing APP as an efficient multifunctional binder toward building next-generation high energy density Li-S batteries.

Tuning the High-Temperature Wetting Behavior of Metals toward Ultrafine Nanoparticles.

The interaction between metal nanoparticles (NPs) and their substrate plays a critical role in determining the particle morphology, distribution, and properties. The pronounced impact of a thin oxide coating on the dispersion of metal NPs on a carbon substrate is presented. Al2 O3 -supported Pt NPs are compared to the direct synthesis of Pt NPs on bare carbon surfaces. Pt NPs with an average size of about 2 nm and a size distribution ranging between 0.5 nm and 4.0 nm are synthesized on the Al2 O3 coated carbon nanofiber, a significant improvement compared to those directly synthesized on a bare carbon surface. First-principles modeling verifies the stronger adsorption of Pt clusters on Al2 O3 than on carbon, which attributes the formation of ultrafine Pt NPs. This strategy paves the way towards the rational design of NPs with enhanced dispersion and controlled particle size, which are promising in energy storage and electrocatalysis.

In Situ Observation and Electrochemical Study of Encapsulated Sulfur Nanoparticles by MoS2 Flakes.

Sulfur is an attractive cathode material for next-generation lithium batteries due to its high theoretical capacity and low cost. However, dissolution of its lithiated product (lithium polysulfides) into the electrolyte limits the practical application of lithium sulfur batteries. Here we demonstrate that sulfur particles can be hermetically encapsulated by leveraging on the unique properties of two-dimensional materials such as molybdenum disulfide (MoS2). The high flexibility and strong van der Waals force in MoS2 nanoflakes allows effective encapsulation of the sulfur particles and prevent its sublimation during in situ TEM studies. We observe that the lithium diffusivities in the encapsulated sulfur particles are in the order of 10-17 m2 s-1. Composite electrodes made from the MoS2-encapsulated sulfur spheres show outstanding electrochemical performance, with an initial capacity of 1660 mAh g-1 and long cycle life of more than 1000 cycles.