Ir Single Atoms Boost Metal-Oxygen Covalency on Selenide-Derived NiOOH for Direct Intramolecular Oxygen Coupling.

This investigation probes the intricate interplay of catalyst dynamics and reaction pathways during the oxygen evolution reaction (OER), highlighting the significance of atomic-level and local ligand structure insights in crafting highly active electrocatalysts. Leveraging a tailored ion exchange reaction followed by electrochemical dynamic reconstruction, we engineered a novel catalytic structure featuring single Ir atoms anchored to NiOOH (Ir1@NiOOH). This novel approach involved the strategic replacement of Fe with Ir, facilitating the transition of selenide precatalysts into active (oxy)hydroxides. This elemental substitution promoted an upward shift in the O 2p band and intensified the metal-oxygen covalency, thereby altering the OER mechanism toward enhanced activity. The shift from a single-metal site mechanism (SMSM) in NiOOH to a dual-metal-site mechanism (DMSM) in Ir1@NiOOH was substantiated by in situ differential electrochemical mass spectrometry (DEMS) and supported by theoretical insights. Remarkably, the Ir1@NiOOH electrode exhibited exceptional electrocatalytic performance, achieving overpotentials as low as 142 and 308 mV at current densities of 10 and 1000 mA cm-2, respectively, setting a new benchmark for the electrocatalysis of OER.

All-Climate Long-Life and Fast-Charging Sodium-Ion Battery using Co3 S4 @NiS2 Heterostructures Encapsulated in Carbon Matrix as Anode.

Sodium-ion (Na-ion) battery is one of the research focuses because of high theoretical capacity and low cost. However, seeking for ideal anodes remains a big challenge. Here, a Co3 S4 @NiS2 /C synthesized by in situ growing NiS2 on CoS spheres then converting to Co3 S4 @NiS2 heterostructures encapsulated by carbon matrix, is developed as a promising anode. Co3 S4 @NiS2 /C as anode displays a high capacity of 654.1 mAh g-1 after 100 cycles. Even over 2000 cycles at a high rate of 10 A g-1 , capacity exceeds 143.2 mAh g-1 . Heterostructures between Co3 S4 and NiS2 improve electron transfer as verified by density functional theory (DFT) calculations. In addition, when cycling at a high temperature of 50 °C, the Co3 S4 @NiS2 /C anode displays 525.2 mAh g-1 , while it remains 340 mAh g-1 at -15 °C, indicating all-climate potential for using under different temperatures.

Long-Cycling-Life Sodium-Ion Battery Using Binary Metal Sulfide Hybrid Nanocages as Anode.

Due to the relatively high capacity and lower cost, transition metal sulfides (TMS) as anode show promising potential in sodium-ion batteries (SIBs). Herein, a binary metal sulfide hybrid consisting of carbon encapsulated CoS/Cu2 S nanocages (CoS/Cu2 S@C-NC) is constructed. The interlocked hetero-architecture filled with conductive carbon accelerates the Na+ /e- transfer, thus leading to improved electrochemical kinetics. Also the protective carbon layer can provide better volume accommondation upon charging/discharging. As a result, the battery with CoS/Cu2 S@C-NC as anode displays a high capacity of 435.3 mAh g-1 after 1000 cycles at 2.0 A g-1 (≈3.4 C). Under a higher rate of 10.0 A g-1 (≈17 C), a capacity of as high as 347.2 mAh g-1 is still remained after long 2300 cycles. The capacity decay per cycle is only 0.017%. The battery also exhibits a better temperature tolerance at 50 and -5 °C. A low internal impedance analyzed by X-ray diffraction patterns and galvanostatic intermittent titration technique, narrow band gap, and high density of states obtained by first-principle calculations of the binary sulfides, ensure the rapid Na+ /e- transport. The long-cycling-life SIB using binary metal sulfide hybrid nanocages as anode shows promising applications in versatile electronic devices.

A Foldable Aqueous Zn-Ion Battery with Gear-Structured Composite as Freestanding Cathode.

A foldable battery with high flexibility provides great potential in various wearable electronic devices for health and fitness tracking, chronic disease management, performance monitoring, navigation tracking, and portable gears for soldiers. We report a highly flexible, self-healing Zn-ion battery with a free-standing cathode that is composed of a 3D gear-like NH4 V4 O10 @C composite on carbon paper. The battery retained a capacity of up to 102.4 mAh g-1 even after being folded 60 times with a high angle of 180°. An aqueous hydrogel consisting polyvinyl alcohol, glycerin and Zn(CF3 SO3 )2 was used as electrolyte, which showed as high as 580 % tensile strain under a loading weight of 78 N. The battery exhibited a better capacity retention of over 100 mAh g-1 and Coulombic efficiency of over 99.8 % after cutting and twisting to 90°, thereby indicating a great self-healing performance. The gear-like geometry greatly improved the volume accommodation due to the increased interval space between the blades and the outward configuration. Meanwhile the Zn2+ ionic conductivity was improved by rapid re-binding of many existing hydroxy groups from the electrolyte and the enhanced contact surface area and diffusion route from the cathode material. The highly flexible, safe aqueous Zn-ion battery opens a practical way to power various carry-on electronics under mechanical agitation.

A Pyramidal Metal-Organic Frameworks-Derived FeP@CoP Aluminium-Ion Battery Cathode Displaying Low-Temperature Tolerance and Fast Electron Transfer Kinetics.

Anhui Provincial Engineering Laboratory for Engineering appropriate cathode materials is significant for the development of high-performance aluminum-ion (Al-ion) batteries. Here, a pyramidal metal-organic frameworks (MOFs)-derived FeP@CoP composite was developed as cathode, which exhibits good stability and high capacity. FeP@CoP cathode maintains a high capacity of 168 mAh g-1 after 200 cycles, and displays a stable rate-performance at both room and low temperatures of -10 °C. After three rounds of rate-performance cycling, the FeP@CoP composite recovers 178.2 mAh g-1 at 0.3 A g-1 . Moreover, density functional theory (DFT) calculations verify improved electron-transfer kinetics with narrowed band gap and enhanced density of states. These findings inspire a broad set of studies on MOFs-derived composites for high-performance secondary batteries.

eg Occupancy as a Predictive Descriptor for Spinel Oxide Nanozymes.

Functional nanomaterials offer an attractive strategy to mimic the catalysis of natural enzymes, which are collectively called nanozymes. Although the development of nanozymes shows a trend of diversification of materials with enzyme-like activity, most nanozymes have been discovered via trial-and-error methods, largely due to the lack of predictive descriptors. To fill this gap, this work identified eg occupancy as an effective descriptor for spinel oxides with peroxidase-like activity and successfully predicted that the eg value of spinel oxide nanozymes with the highest activity is close to 0.6. The LiCo2O4 with the highest activity, which is finally predicted, has achieved more than an order of magnitude improvement in activity. Density functional theory provides a rationale for the reaction path. This work contributes to the rational design of high performance nanozymes by using activity descriptors and provides a methodology to identify other descriptors for nanozymes.

In Situ Formation of Polycyclic Aromatic Hydrocarbons as an Artificial Hybrid Layer for Lithium Metal Anodes.

Nonuniform Li deposition causes dendrites and low Coulombic efficiency (CE), seriously hindering the practical applications of Li metal. Herein, we developed an artificial solid-state interphase (SEI) with planar polycyclic aromatic hydrocarbons (PAHs) on the surface of Li metal anodes by a facile in situ formation technology. The resultant dihydroxyviolanthron (DHV) layers serve as the protective layer to stabilize the SEI. In addition, the oxygen-containing functional groups in the soft and conformal SEI film can regulate the diffusion and transport of Li ions to homogenize the deposition of Li metal. The artificial SEI significantly improves the CEs and shows superior cyclability of over 1000 h at 4 mAh cm-2. The LiFePO4/Li cell (2.8 mAh cm-2) enables a long cyclability for 300 cycles and high CEs of 99.8%. This work offers a new strategy to inhibit Li dendrite growth and enlightens the design on stable SEI for metal anodes.

Cu2O/SrTi1-xCrxO3 Heterojunction Photocatalyst for the Efficient Degradation of Isopropanol under Visible Light Irradiation.

A heterojunction of Cu2O and Cr-doped SrTiO3 (SrTi1-xCrxO3) was designed for selective photocatalytic isopropanol (IPA) oxidation under visible light irradiation. The photocatalytic oxidation of IPA was measured in a fixed-bed reactor. Cr dopants can increase the light absorption and improve the activity of the catalyst. The formation of the Cu2O/SrTi1-xCrxO3 heterojunction can further broaden the absorption range of lights and dramatically increase the photocatalytic activity for selective oxidation of IPA. The 3% Cu2O/SrTi0.99Cr0.01O3 catalyst can fully convert ∼1000 ppm IPA under illumination in 2 h. The selectivity of acetone is ∼100%. The yield is 83 and 4 times higher than that using SrTiO3 and SrTi0.99Cr0.01O3 as catalysts, respectively. By measuring the ultraviolet-visible absorption spectra and Mott-Schottky plots, we obtained the band structure of the heterojunction, which shows that the conduction and valence bands of Cu2O are higher than those of SrTi1-xCrxO3, therefore facilitating the separation and transfer of photogenerated electrons and holes. In addition, electron paramagnetic resonance spectroscopy and radical trapping tests reveal that the generation of hydroxyl and superoxide leads to photocatalytic oxidation of IPA by the heterojunction photocatalyst.

Engineering Two-Dimensional Metal-Organic Framework on Molecular Basis for Fast Li+ Conduction.

Metal-organic frameworks (MOFs) have been proposed as emerging fillers for composite polymer electrolytes (CPEs). However, MOF particles are usually served as passive fillers that yield limited ionic conductivity improvement. Building continuous MOF reinforcements and exploiting their active roles remain challenging. Here we demonstrate the feasibility of engineering fast Li+ conduction within MOF on molecule conception. Two-dimensional Cu(BDC) MOF is selected as an active filler due to its sufficient accessible open metal sites for perchlorate anion anchoring to release free Li+, verified by theoretical calculations and measurements. A novel Cu(BDC)-scaffold-reinforced CPE is developed via in situ growth of MOF, which provides fast Li+ channels inside MOF and continuous Li+ paths along the MOF/polymer interface for high Li+ conductivity (ambient 0.24 mS cm-1) and enables high mechanical strength. Stable cycling is achieved in solid-state Li-NCM811 full cell using the MOF-reinforced CPE. This molecule-basis Li+ conduction strategy brings new ideas for designing advanced CPEs.

A Valence-Engineered Self-Cascading Antioxidant Nanozyme for the Therapy of Inflammatory Bowel Disease.

Antioxidant treatment strategy by scavenging reactive oxygen species (ROS) is a highly effective disease treatment option. Nanozymes with multiple antioxidant activities can cope with the diverse ROS environment. However, lack of design strategies and limitation of negative correlation for nanozymes with multiple antioxidant activities hindered their development. To overcome these difficulties, here we used ZnMn2 O4 as a model to explore the role of Mn valency at the octahedral site via a valence-engineered strategy, and found that its multiple antioxidant activities are positively correlated with the content of Mn4+ . Therefore, through this strategy, a self-cascading antioxidant nanozyme LiMn2 O4 was constructed, and its efficacy was verified at the cellular level and in an inflammatory bowel disease model. This work not only provides guidance for the design of multiple antioxidant nanozymes, but also broadens the biomedical application potential of multiple antioxidant nanozymes.

A Polysulfides-Confined All-in-One Porous Microcapsule Lithium-Sulfur Battery Cathode.

Developing emerging materials for high energy-density lithium-sulfur (Li-S) batteries is of great significance to suppress the shuttle effect of polysulfides and to accommodate the volumetric change of sulfur. Here, a novel porous microcapsule system containing a carbon nanotubes/tin dioxide quantum dots/S (CNTs/QDs/S) composite core and a porous shell prepared through a liquid-driven coaxial microfluidic method as Li-S battery cathode is developed. The encapsulated CNTs in the microcapsules provide pathways for electron transport; SnO2 QDs on CNTs immobilize the polysulfides by strong adsorption, which is verified by using density functional theory calculations on binding energies. The porous shell of the microcapsule is beneficial for ion diffusion and electrolyte penetration. The void inside the microcapsule accommodates the volumetric change of sulfur. The Li-S battery based on the porous CNTs/QDs/S microcapsules displays a high capacity of 1025 mAh g-1 after 100 cycles at 0.1 C. When the sulfur loading is 2.03 mg cm-2 , the battery shows a stable cycling life of 700 cycles, a Coulombic efficiency exceeding 99.9%, a recoverable rate-performance during repeated tests, and a good temperature tolerance at both -5 and 45 °C, which indicates a potential for applications at different conditions.

In operando plasmonic monitoring of electrochemical evolution of lithium metal.

The recent renaissance of lithium metal batteries as promising energy storage devices calls for in operando monitoring and control of electrochemical evolution of lithium metal morphologies. While the development of plasmonics has led to significant advancement in real-time and ultrasensitive chemical and biological sensing and surface-enhanced spectroscopies, alkali metals featured by ideal free electron gas models have long been regarded as promising plasmonic materials but seldom been explored due to their high chemical reactivity. Here, we demonstrate the in operando plasmonic monitoring of the electrochemical evolution of lithium metal during battery cycling by taking advantage of selective electrochemical deposition. The relationships between the evolving morphologies of lithium metal and in operando optical spectra are established both numerically and experimentally: Ordered growth of lithium particles shows clear size-dependent reflective dips due to hybrid surface plasmon resonances, while the formation of undesirable disordered lithium dendrites exhibits a flat spectroscopic profile with pure suppression in reflection intensity. Under the in operando plasmonic monitoring enabled by the microscopic morphology of metal, the differences of lithium evolutionary behaviors with different electrolytes can be conveniently identified without destruction. At the intersection of energy storage and plasmonics, it is expected that the ability to actively control and in operando plasmonically monitor electrochemical evolution of lithium metal can provide a promising platform for investigating lithium metal behavior during electrochemical cycling under various working conditions.

[A review of brain-like spiking neural network and its neuromorphic chip research].

Under the current situation of the rapid development of brain-like artificial intelligence and the increasingly complex electromagnetic environment, the most bionic and anti-interference spiking neural network has shown great potential in computing speed, real-time information processing, and spatiotemporal data processing. Spiking neural network is the core part of brain-like artificial intelligence, which realizes brain-like computing by simulating the structure of biological neural network and the way of information transmission. This article first summarizes the advantages and disadvantages of the five models, and analyzes the characteristics of several network topologies. Then, it summarizes the spiking neural network algorithms. The unsupervised learning based on spike timing dependent plasticity (STDP) rules and four types of supervised learning algorithms are analyzed. Finally, the research on brain-like neuromorphic chips at home and abroad are reviewed. This paper aims to provide learning ideas and research directions for new colleagues in the field of spiking neural network.

Oxygen-Deficient Ferric Oxide as an Electrochemical Cathode Catalyst for High-Energy Lithium-Sulfur Batteries.

Lithium-sulfur batteries, as one of promising next-generation energy storage devices, hold great potential to meet the demands of electric vehicles and grids due to their high specific energy. However, the sluggish kinetics and the inevitable "shuttle effect" severely limit the practical application of this technology. Recently, design of composite cathode with effective catalysts has been reported as an essential way to overcome these issues. In this work, oxygen-deficient ferric oxide (Fe2 O3- x ), prepared by lithiothermic reduction, is used as a low-cost and effective cathodic catalyst. By introducing a small amount of Fe2 O3- x into the cathode, the battery can deliver a high capacity of 512 mAh g-1 over 500 cycles at 4 C, with a capacity fade rate of 0.049% per cycle. In addition, a self-supporting porous S@KB/Fe2 O3- x cathode with a high sulfur loading of 12.73 mg cm-2 is prepared by freeze-drying, which can achieve a high areal capacity of 12.24 mAh cm-2 at 0.05 C. Both the calculative and experimental results demonstrate that the Fe2 O3- x has a strong adsorption toward soluble polysulfides and can accelerate their subsequent conversion to insoluble products. As a result, this work provides a low-cost and effective catalyst candidate for the practical application of lithium-sulfur batteries.

A novel sulfur@void@hydrogel yolk-shell particle with a high sulfur content for volume-accommodable and polysulfide-adsorptive lithium-sulfur battery cathodes.

High-energy-density secondary batteries are required for many applications such as electric vehicles. Lithium-sulfur (Li-S) batteries are receiving broad attention because of their high theoretical energy density. However, the large volume change of sulfur during cycling, poor conductivity, and the shuttle effect of sulfides severely restrict the Li-storage performance of Li-S batteries. Herein, we present a novel core-shell nanocomposite consisting of a sulfur core and a hydrogel polypyrrole (PPy) shell, enabling an ultra-high sulfur content of about 98.4% within the composite, which greatly exceeds many other conventional composites obtained by coating sulfur onto some hosts. In addition, the void inside the core-shell structure effectively accommodates the volume change; the conductive PPy shell improves the conductivity of the composite; and PPy is able to adsorb polysulfides, suppressing the shuttle effect. After cycling for 200 cycles, the prepared S@void@PPy composite retains a stable capacity of 650 mAh g-1, which is higher than the bare sulfur particles. The composite also exhibits a fast Li ion diffusion coefficient. Furthermore, the density functional theory calculations show the PPy shell is able to adsorb polysulfides efficiently, with a large adsorption energy and charge density transfer.

Novel Co2 VO4 Anodes Using Ultralight 3D Metallic Current Collector and Carbon Sandwiched Structures for High-Performance Li-Ion Batteries.

A novel spinel Co2 VO4 is studied as the Li-ion battery anode material and it is sandwiched with a 3D ultralight porous current collector (PCC) and amorphous carbon. Co2 VO4 demonstrates the high capacity and excellent cyclability because of the mixed lithium storage mechanisms. The 3D composite structure requires no binders and replaces the conventional current collector (Cu foil) with a 3D ultralight porous metal scaffold, yielding the high electrode-based capacity. Such a novel composite anode also enables the close adhesion of Co2 VO4 to the PCC scaffold. The resulting monolithic electrode has the rapid electron pathway and stable mechanical properties, which lead to the excellent rate capabilities and cycling properties. At a current density of 1 A g-1 , the PCC and carbon sandwiched Co2 VO4 anode is able to deliver a stable reversible capacity of about 706.8 mAh g-1 after 1000 cycles. Generally, this study not only develops a new Co2 VO4 anode with high capacity and good cyclability, but also demonstrates an alternative approach to improve the electrochemical properties of high capacity anode materials by using ultralight porous metallic current collector instead of heavy copper foil.

V-Doped CoSe2 Nanowire Catalysts in a 3D-Structured Electrode for Durable Li-S Pouch Cells.

Lithium-sulfur (Li-S) batteries have high theoretical energy density and are regarded as a promising candidate for next-generation energy storage systems. However, their practical applications are hindered by the slow kinetics of sulfur conversion and polysulfide shuttling. In particular, large-scale pouch cells show much poor cyclability. Here, we develop a high-efficiency catalyst of V-doped CoSe2 by studying the binary CoSe2-VSe2 system and confirming its effectiveness in accelerating polysulfide conversion. The coin cell tests reveal an initial capacity of 1414 mAh g-1 at 0.1 C and 1049 mAh g-1 at 1 C and demonstrate 1000 times cyclability with a decaying rate of 0.05% per cycle. Furthermore, the assembly and construction of pouch cells were optimized with monolithic three-dimensional (3D) electrodes and a multistacking strategy. Specifically, a 3D metallic scaffold (3MS) was developed to host V-doped CoSe2 nanowires and sulfur. In addition, Janus microspheres of C@TiO2 were synthesized to capture polar polysulfides with their polar part of TiO2 and adsorb nonpolar sulfur with their nonpolar part of carbon. By integrating with 3MS, C@TiO2 microspheres can block all ion channels of 3MS and only allow Li ions in and out. These integral designs and monolithic structures enable multistacking pouch cells with high cyclability. A high-loading pouch cell was demonstrated with a total capacity of 700 mAh. The cell can be cycled for 70 times with a capacity retention of 65.7%. In brief, this work provides an integral strategy of catalyst design and overall 3D assembly for practical Li-S batteries in a large pouch cell format.

Boron-Doped Dinickel Phosphide to Enhance Polysulfide Conversion and Suppress Shuttling in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are promising for next-generation high-energy energy storage systems. However, the slow reaction kinetics render mobile polysulfides hardly controlled, yielding shuttling effects and eventually damaging Li metal anodes. To improve the cyclability of Li-S batteries, high-efficiency catalysts are desired to accelerate polysulfide conversion and suppress the shuttling effect. Herein, we studied a doping system with Ni2P and Ni2B as the end members and found a B-doped Ni2P catalyst that demonstrates high activity for Li-S batteries. As anionic dopants, B demonstrates an interesting reverse electron transfer to P and tunes the electronic structure of Ni2P dramatically. The resultant B-doped Ni2P exhibits short Ni-B bonds and strong Ni-S interaction, and the electron donation of B to P further enhances the adsorption of polysulfide on catalysts. The S-S bonds of polysulfides were activated appropriately, therefore decreasing a low energy barrier for conversion reactions.

Gas-phase synthesis of Ti2CCl2 enables an efficient catalyst for lithium-sulfur batteries.

MXenes have aroused intensive enthusiasm because of their exotic properties and promising applications. However, to date, they are usually synthesized by etching technologies. Developing synthetic technologies provides more opportunities for innovation and may extend unexplored applications. Here, we report a bottom-up gas-phase synthesis of Cl-terminated MXene (Ti2CCl2). The gas-phase synthesis endows Ti2CCl2 with unique surface chemistry, high phase purity, and excellent metallic conductivity, which can be used to accelerate polysulfide conversion kinetics and dramatically prolong the cyclability of Li-S batteries. In-depth mechanistic analysis deciphers the origin of the formation of Ti2CCl2 and offers a paradigm for tuning MXene chemical vapor deposition. In brief, the gas-phase synthesis transforms the synthesis of MXenes and unlocks the hardly achieved potentials of MXenes.

Three-dimensional metal scaffold supported bicontinuous silicon battery anodes.

Silicon-based lithium ion battery anodes are attracting significant attention because of silicon's exceptionally high lithium capacity. However, silicon's large volume change during cycling generally leads to anode pulverization unless the silicon is dispersed throughout a matrix in nanoparticulate form. Because pulverization results in a loss of electric connectivity, the reversible capacity of most silicon anodes dramatically decays within a few cycles. Here we report a three-dimensional (3D) bicontinuous silicon anode formed by depositing a layer of silicon on the surface of a colloidal crystal templated porous nickel metal scaffold, which maintains electrical connectivity during cycling due to the scaffold. The porous metal framework serves to both impart electrical conductivity to the anode and accommodate the large volume change of silicon upon lithiation and delithiation. The initial capacity of the bicontinuous silicon anode is 3568 (silicon basis) and 1450 mAh g(-1) (including the metal framework) at 0.05C. After 100 cycles at 0.3C, 85% of the capacity remains. Compared to a foil-supported silicon film, the 3D bicontinuous silicon anode exhibits significantly improved mechanical stability and cycleability.