Anchoring and Catalytic Effects of rGO Supported VS2 Nanosheets Enable High-Performance Li–Organosulfur Battery

As a high-energy-density cathode material, organosulfur has great potential for lithium batteries. However, their practical application is plagued by electronic/ionic insulation and sluggish redox kinetics. Hence, our strategy is to design a self-weaving, freestanding host material by introducing reduced graphene oxide–supported VS₂ nanosheets (VS₂-rGO) and carbon nanotubes (CNTs) for lithium–phenyl tetrasulfide (Li–PTS) batteries. Unique host materials not only provide physicochemical confinement of active materials to boost the utilization but also catalyze the conversion of active materials to accelerate redox kinetics. Therefore, Li–PTS cell based on the 3D VS₂-rGO-CNTs (VSGC) host material shows excellent cyclability, with a slow capacity decay rate of 0.08% per cycle over 500 cycles at 0.5 C, and a high areal capacity of 3.1 mAh cm⁻² with the PTS loading of 7.2 mg cm⁻². More importantly, the potential for practical applications is highlighted by the flexible pouch cell with a high areal capacity (4.1 mAh cm⁻²) and a low electrolyte/PTS ratio (3.5 µL mg⁻¹). This work sheds light on elevating the electrochemical performance of Li–organosulfur batteries through the effective catalytic and adsorbed host material.     

Ultrathin Co-N-C Layer Modified Pt–Co Intermetallic Nanoparticles Leading to a High-Performance Electrocatalyst toward Oxygen Reduction and Methanol Oxidation

The development of low platinum-based alloy electrocatalysts is crucial to accelerate the commercialization of fuel cells, yet remains a synthetic challenge and an incompatibility between activity and stability. Herein, a facile procedure to fabricate a high-performance composite that comprises Pt–Co intermetallic nanoparticles (IMNs) and Co, N co-doped carbon (Co-N-C) electrocatalyst is proposed. It is prepared by direct annealing of homemade carbon black-supported Pt nanoparticles (Pt/KB) covered with a Co-phenanthroline complex. During this process, most of Co atoms in the complex are alloyed with Pt to form ordered Pt–Co IMNs, while some Co atoms are atomically dispersed and doped in the framework of superthin carbon layer derived from phenanthroline, which is coordinated with N to form Co–N_x moieties. Moreover, the Co-N-C film obtained from complex is observed to cover the surface of Pt–Co IMNs, which prevent the dissolution and agglomeration of nanoparticles. The composite catalyst exhibits high activity and stability toward oxygen reduction reactions (ORR) and methanol oxidation reactions (MOR), delivering outstanding mass activities of 1.96 and 2.92 A mg_Pt⁻¹ for ORR and MOR respectively, owing to the synergistic effect of Pt–Co IMNs and Co-N-C film. This study may provide a promising strategy to improve the electrocatalytic performance of Pt-based catalysts.     

Yolk–Shell Cu2O@CuO-decorated RGO for High-Performance Lithium-Ion Battery Anode

Based on the great advantages of an inner hollow structure and excellent solid counterpart capacity, complex hierarchical structures have been widely used as electrodes for lithium-ion batteries. Herein, hierarchical yolk–shell Cu₂O@Cu O-decorated RGO(YSRs) was designed and synthesized via a multistep approach. Octahedron-like Cu₂O-decorated RGO was firstly produced, in which GO was reduced slightly while cuprous oxide was synthesized.Subsequently, the controlled oxidation ...     

Regulating Electrochemical Kinetics of CoP by Incorporating Oxygen on Surface for High-Performance Li–S Batteries

Lithium–sulfur (Li–S) batteries are widely studied because of their high theoretical specific capacity and environmental friendliness. However, the further development of Li–S batteries is hindered by the shuttle effect of lithium polysulfides (LiPSs) and the sluggish redox kinetics. Since the adsorption and catalytic conversion of LiPSs mainly occur on the surface of the electrocatalyst, regulating the surface structure of electrocatalysts is an advisable strategy to solve the obstacles in Li–S batteries. Herein, CoP nanoparticles with high oxygen content on surface embedded in hollow carbon nanocages (C/O-CoP) is employed to functionalize the separators and the effect of the surface oxygen content of CoP on the electrochemical performance is systematically explored. Increasing the oxygen content on CoP surface can enhance the chemical adsorption to lithium polysulfides and accelerate the redox conversions kinetics of polysulfides. The cell with C/O-CoP modified separator can achieve the capacity of 1033 mAh g⁻¹ and maintain 749 mAh g⁻¹ after 200 cycles at 2 C. Moreover, DFT calculations are used to reveal the enhancement mechanism of oxygen content on surface of CoP in Li–S chemistry. This work offers a new insight into developing high-performance Li–S batteries from the perspective of surface engineering.     

Tailoring the p-Band Center of N?S Pair for Accelerating High-Performance Lithium–Oxygen Battery

The local coordination environment of catalytical moieties directly determines the performance of electrochemical energy storage and conversion devices, such as Li–O₂ batteries (LOBs) cathode. However, understanding how the coordinative structure affects the performance, especially for non-metal system, is still insufficient. Herein, a strategy that introduces S-anion to tailor the electronic structure of nitrogen–carbon catalyst (SNC) is proposed to improve the LOBs performance. This study unveils that the introduced S-anion effectively manipulates the p-band center of pyridinic-N moiety, substantially reducing the battery overpotential by accelerating the generation and decomposition of intermediate products Li_1–3O₄. The lower adsorption energy of discharging product Li₂O₂ on N S pair accounts for the long-term cyclic stability by exposing the high active area under operation condition. This work demonstrates an encouraging strategy to enhance LOBs performance by modulating the p-band center on non-metal active sites.     

Large Area Self-Assembled Ultrathin Polyimine Nanofilms Formed at the Liquid–Liquid Interface Used for Molecular Separation

Separation membranes with higher molecular weight cut-offs are needed to separate ions and small molecules from a mixed feed. The molecular sieving phenomenon can be utilized to separate smaller species with well-defined dimensions from a mixture. Here, the formation of freestanding polyimine nanofilms with thicknesses down to ≈14 nm synthesized via self-assembly of pre-synthesized imine oligomers is reported. Nanofilms are fabricated at the water–xylene interface followed by reversible condensation of polymerization according to the Pieranski theory. Polyimine nanofilm composite membranes are made via transferring the freestanding nanofilm onto ultrafiltration supports. High water permeance of 49.5 L m^-2 h⁻¹ bar⁻¹ is achieved with a complete rejection of brilliant blue-R (BBR; molecular weight = 825 g mol⁻¹) and no more than 10% rejection of monovalent and divalent salts. However, for a mixed feed of BBR dye and monovalent salt, the salt rejection is increased to ≈18%. Membranes are also capable of separating small dyes (e.g., methyl orange; MO; molecular weight = 327 g mol⁻¹) from a mixed feed of BBR and MO. Considering a thickness of ≈14 nm and its separation efficiency, the present membrane has significance in separation processes.     

Molybdenum Boride as an Efficient Catalyst for Polysulfide Redox to Enable High-Energy-Density Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries, despite having high theoretical specific energy, possess many practical challenges, including lithium polysulfide (LiPS) shuttling. To address the issues, here, hydrophilic molybdenum boride (MoB) nanoparticles are presented as an efficient catalytic additive for sulfur cathodes. The high conductivity and rich catalytically active sites of MoB nanoparticles allow for a fast kinetics of LiPS redox in high-sulfur-loading electrodes (6.1 mg cm⁻²). Besides, the hydrophilic properties and good wettability toward electrolyte of MoB can facilitate electrolyte penetration and LiPS redox, guaranteeing a high utilization of sulfur under a lean-electrolyte condition. Therefore, the cells with MoB achieve impressive electrochemical performance, including a high capacity (1253 mA h g⁻¹) and ultralong lifespan (1000 cycles) with a low capacity fade rate of 0.03% per cycle. Also, pouch cells fabricated with the MoB additive deliver an ultrahigh discharge capacity of 947 mA h g⁻¹, corresponding to a low electrolyte-to-capacity ratio of about 4.8 µL (mA h)⁻¹, and remain stable over 55 cycles under practically necessary conditions with a low electrolyte-to-sulfur ratio of 4.5 µL mg⁻¹.     

Diode-Like Selective Enhancement of Carrier Transport through Metal–Semiconductor Interface Decorated by Monolayer Boron Nitride

2D semiconductors such as monolayer molybdenum disulfide (MoS₂) are promising material candidates for next-generation nanoelectronics. However, there are fundamental challenges related to their metal–semiconductor (MS) contacts, which limit the performance potential for practical device applications. In this work, 2D monolayer hexagonal boron nitride (h-BN) is exploited as an ultrathin decorating layer to form a metal–insulator–semiconductor (MIS) contact, and an innovative device architecture is designed as a platform to reveal a novel diode-like selective enhancement of the carrier transport through the MIS contact. The contact resistance is significantly reduced when the electrons are transported from the semiconductor to the metal, but is barely affected when the electrons are transported oppositely. A concept of carrier collection barrier is proposed to interpret this intriguing phenomenon as well as a negative Schottky barrier height obtained from temperature-dependent measurements, and the critical role of the collection barrier at the drain end is shown for the overall transistor performance.     

Molecular Dynamics Simulation of Pervaporation of an Ethanol–Water Mixture on a Hybrid Silicon Oxide Membrane

A molecular-statistical method for simulating the process of pervaporation on hybrid silicon oxide membranes is proposed. This method is a development of the control volume method. Models of three membrane samples with different densities and pore sizes were obtained. These samples were used for the molecular-dynamics simulation of pervaporation of a 95 mol % aqueous solution of ethanol at a temperature of 343 K. It is shown that the membrane is selective with respect to water; the component flow is found to exponentially depend on the pore size.     

A Transmetalation Synthetic Strategy to Engineer Atomically Dispersed MnN2O2 Electrocatalytic Centers Driving High-Performance Li?S Battery

Sluggish sulfur redox reaction (SROR) kinetics accompanying lithium polysulfides (LiPSs) shuttle effect becomes a stumbling block for commercial application of Li S battery. High-efficient single atom catalysts (SACs) are desired to improve the SROR conversion capability; however, the sparse active sites as well as partial sites encapsulated in bulk-phase are fatal to the catalytic performance. Herein, high loading (5.02 wt.%) atomically dispersed manganese sites (MnSA) on hollow nitrogen-doped carbonaceous support (HNC) are realized for the MnSA@HNC SAC by a facile transmetalation synthetic strategy. The thin-walled hollow structure (≈12 nm) anchoring the unique trans-MnN₂O₂ sites of MnSA@HNC provides a shuttle buffer zone and catalytic conversion site for LiPSs. Both electrochemical measurement and theoretical calculation indicate that the MnSA@HNC with abundant trans-MnN₂O₂ sites have extremely high bidirectional SROR catalytic activity. The assembled Li S battery based on the MnSA@HNC modified separator can deliver a large specific capacity of 1422 mAh g⁻¹ at 0.1 C and stable cycling over 1400 cycles with an ultralow decay rate of 0.033% per cycle at 1 C. More impressively, a flexible pouch cell on account of the MnSA@HNC modified separator may release a high initial specific capacity of 1192 mAh g⁻¹ at 0.1 C and uninterruptedly work after the bending-unbending processes.     

A Facile Molecular Approach to Amorphous Nickel Pnictides and Their Reconstruction to Crystalline Potassium-Intercalated γ-NiOOHx Enabling High-Performance Electrocatalytic Water Oxidation and Selective Oxidation of 5-Hydroxymethylfurfural

The low-temperature molecular precursor approach can be beneficial to conventional solid-state methods, which require high temperatures and lead to relatively large crystalline particles. Herein, a novel, single-step, room-temperature preparation of amorphous nickel pnictide (NiE; EP, As) nanomaterials is reported, starting from NaOCE(dioxane)_n and NiBr₂(thf)_1.5. During application for the oxygen evolution reaction (OER), the pnictide anions leach, and both materials fully reconstruct into nickel(III/IV) oxide phases (similar to γ-NiOOH) comprising edge-sharing (NiO₆) layers with intercalated potassium ions and a d-spacing of 7.27 Å. Remarkably, the intercalated γ-NiOOH_x phases are nanocrystalline, unlike the amorphous nickel pnictide precatalysts. This unconventional reconstruction is fast and complete, which is ascribed to the amorphous nature of the nanostructured NiE precatalysts. The obtained γ-NiOOH_x can effectively catalyse the OER for 100 h at a high current density (400 mA cm⁻²) and achieves outstandingly high current densities (>600 mA cm⁻²) for the selective, value-added oxidation of 5-hydroxymethylfurfural (HMF). The NiP-derived γ-NiOOH_x shows a higher activity for both processes due to more available active sites. It is anticipated that the herein developed, effective, room-temperature molecular synthesis of amorphous nickel pnictide nanomaterials can be applied to other functional transition-metal pnictides.     

Regulating the Active Sites of Metal–Phthalocyanine at the Molecular Level for Efficient Water Electrolysis: Double Deciphering of Electron-Withdrawing Groups and Bimetallic

Implementing a molecular modulation strategy for metallic phthalocyanines (MPc) without losing the activity of the metal center and inducing a multifunction characteristic in electrocatalytic remains a challenge. Herein, a series of 2D CuCo bimetallic polymerized phthalocyanine modified with strong electron-withdrawing groups (CuCoPc-g, g = F, Cl, Br, NO₂) for water oxidation in the alkaline electrolyte is designed and simply synthesized. The experimental results testify that the bimetallic design can perform electronic adjustment once and introduce the second active sites to get bifunctional characteristics, and then the electronic structure of the active center can be regulated by electron-withdrawing groups for a second time to achieve the optimal state. These electrons that transfer in the active center of inner metal can generate space-charged regions and the design of the polymer can stabilize active site region to maintain long-term electrolytic stability and high activity. This study precisely regulates the electronic structure of MPc at the molecular level and provides insight into the multifunctional design of polymeric macrocyclic electrocatalysts.     

An investigation to the microstructural evolution of Fe–29Mn–5Al dual-phase twinning-induced plasticity steel through annealing

The potential effects of twinning induced plasticity have been taken into consideration to further improve the mechanical properties of advanced high-strength steels. Accordingly the high-Mn twinning-induced plasticity (TWIP) steels with austenite–ferrite dual-phase microstructure have been developed. In the present study, the influence of cold rolling and post-annealing treatments on the microstructural evolution and mechanical behavior of a group of dual-phase TWIP steel as a function of annealing time have been investigated. The mechanical behavior of processed materials has been examined through applying a set of low strain rate (0.001 s⁻¹) compression tests at room temperature. The austenite recrystallization characteristics during various annealing conditions are explained through proper microstructural examinations. The results indicate that as the recrystallization proceeds with annealing time the related yield stress deceases. The rapid drop of yield stress in short annealing periods is related to the onset of recrystallization. The yield stress variation diminishes as the annealing duration increases. This is attributed to the formation of austenite side-plates which may balance the softening effects of restoration processes.     

Regulating the Electronic Structure of Bismuth Nanosheets by Titanium Doping to Boost CO2 Electroreduction and Zn–CO2 Batteries

The electrochemical carbon dioxide reduction reaction (E-CO₂RR) to formate is a promising strategy for mitigating greenhouse gas emissions and addressing the global energy crisis. Developing low-cost and environmentally friendly electrocatalysts with high selectivity and industrial current densities for formate production is an ideal but challenging goal in the field of electrocatalysis. Herein, novel titanium-doped bismuth nanosheets (Ti Bi NSs) with enhanced E-CO₂RR performance are synthesized through one-step electrochemical reduction of bismuth titanate (Bi₄Ti₃O₁₂). We comprehensively evaluated Ti Bi NSs using in situ Raman spectra, finite element method, and density functional theory. The results indicate that the ultrathin nanosheet structure of Ti Bi NSs can accelerate mass transfer, while the electron-rich properties can accelerate the production of *CO₂⁻ and enhance the adsorption strength of *OCHO intermediate. The Ti Bi NSs deliver a high formate Faradaic efficiency (FE_formate) of 96.3% and a formate production rate of 4032 µmol h⁻¹ cm⁻² at −1.01 V versus RHE. An ultra-high current density of −338.3 mA cm⁻² is achieved at −1.25 versus RHE, and simultaneously FE_formate still reaches more than 90%. Furthermore, the rechargeable Zn–CO₂ battery using Ti Bi NSs as a cathode catalyst achieves a maximum power density of 1.05 mW cm⁻² and excellent charging/discharging stability of 27 h.     

Identification of an extended Bouc–Wen model with application to seismic protection through hysteretic devices

In this paper is proposed an extended Bouc–Wen model for improving its capability to approximate experimental symmetric hysteretic loops. On the basis of the generalized equation there are defined integral and differential conditions that describe the essential geometric properties of a hysteretic curve. Next, a new method based on Genetic Algorithms is developed to identify the Bouc–Wen model parameters from experimental hysteretic loops obtained from periodic loading tests. The performance of presented approach is illustrated for two types of seismic protection devices with hysteretic characteristics: elastomeric base isolators and buckling restrained dissipative braces. The applicability of proposed method is highlighted by using the derived models to analyse by numerical simulation the efficiency of these devices for reducing seismic response of a three stories civil structure.     

Controllable Singlet–Triplet Energy Splitting of Graphene Quantum Dots through Oxidation: From Phosphorescence to TADF

Long-lived afterglow emissions, such as room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF), are beneficial in the fields of displays, bioimaging, and data security. However, it is challenging to realize a single material that simultaneously exhibits both RTP and TADF properties with their relative strengths varied in a controlled manner. Herein, a new design approach is reported to control singlet–triplet energy splitting (∆E_ST) in graphene quantum dots (GQD)/graphene oxide quantum dots (GOQDs) by varying the ratio of oxygenated carbon to sp² carbon (γ_OC). It is demonstrated that ∆E_ST decreases from 0.365 to 0.123 eV as γ_OC increases from 4.63% to 59.6%, which in turn induces a dramatic transition from RTP to TADF. Matrix-assisted stabilization of triplet excited states provides ultralong lifetimes to both RTP and TADF. Embedded in boron oxynitride, the low oxidized (4.63%) GQD exhibits an RTP lifetime (τ^T_avg) of 783 ms, and the highly oxidized (59.6%) GOQD exhibits a TADF lifetime (τ^DF_avg) of 125 ms. Furthermore, the long-lived RTP and TADF materials enable the first demonstration of anticounterfeiting and multilevel information security using GQD. These results will open up a new approach to the engineering of singlet–triplet splitting in GQD for controlled realization of smart multimodal afterglow materials.     

A general formula for the transmission coefficient through a barrier and application to I–V characteristic

A general formula providing the transmission coefficient through a given barrier, sandwiched by semiconductor reservoirs under bias is presented in terms of the incoming carrier energy and the logarithmic wave function derivative at the start of the barrier. Furthermore, the formula involves the carrier effective masses in the barrier and reservoir regions. The procedure employed is based on solving an appropriate Riccati equation governing the logarithmic derivative along the barrier width at the end of which it is known in terms of the carrier energy and applied bias. On account of the facility provided for obtaining the transmission coefficient we obtained the I–V characteristic of a quantum dot carved barrier, which exhibits a region of quite a large negative differential resistance together with a high peak to valley ratio. Under the circumstances, the possibility of developing a nanostructure switch utilizing a small variation in the applied bias exists.     

Maximisation of the ratio of microhardness to the Young's modulus of Ti–12Mo–13Nb alloy through microstructure changes

Alloys for orthopaedic and dentistry applications require high mechanical strength and a low Young's modulus to avoid stress shielding. Metastable β titanium alloys appear to fulfil these requirements. This study investigated the correlation of phases precipitated in a Ti–12Mo–13Nb alloy with changes in hardness and the Young's modulus. The alloy was produced by arc melting under an argon atmosphere, after which, it was heat treated and cold forged. Two different routes of heat treatment were employed. Phase transformations were studied by employing X-ray diffraction and transmission electron microscopy. Property characterisation was based on Vickers microhardness tests and Young's modulus measurements. The highest ratio of microhardness to the Young's modulus was obtained using thermomechanical treatment, which consists of heating at 1000 °C for 24 h, water quenching, cold forging to reduce 80% of the area, and ageing at 500 °C for 24 h, where the final microstructure consisted of an α phase dispersed in a β matrix. The α phase appeared in two different forms: as fine lamellas (with 240 ± 100 nm length) and massive particles of 200–500 nm size.     

Tetrahedral Bonding Structure (Ni3-Se) Induced by Lattice-Distortion of Ni to Achieve High Catalytic Activity in Na–Se Battery

Fabrication of transition-metal catalytic materials is regarded as a promising strategy for developing high-performance sodium–selenium (Na–Se) batteries. However, more systematic explorations are further demanded to find out how their bonding interactions and electronic structures can affect the Na storage process. This study finds that lattice-distorted nickel (Ni) structure can form different bonding structures with Na₂Se₄, providing high activity to catalyze the electrochemical reactions in Na–Se batteries. Using this Ni structure to prepare electrode (Se@NiSe₂/Ni/CTs) can realize rapid charge transfer and high cycle stability of the battery. The electrode exhibits high storage performance of Na⁺; i.e., 345 mAh g⁻¹ at 1 C after 400 cycles, and 286.4 mAh g⁻¹ at 10 C in rate performance test. Further results reveal the existence of a regulated electronic structure with upshifts of the d-band center in the distorted Ni structure. This regulation changes the interaction between Ni and Na₂Se₄ to form a Ni₃–Se tetrahedral bonding structure. This bonding structure can provide higher adsorption energy of Ni to Na₂Se₄ to facilitate the redox reaction of Na₂Se₄ during the electrochemical process. This study can inspire the design of bonding structure with high performance in conversion-reaction-based batteries.