Resistance of Cement-based Grouting Materials with Nano- SiO_(2) Emulsion to Chloride Ion Penetration

The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.

Optimization Strategies of Na_(3)V_(2)(PO_(4))_(3) Cathode Materials for Sodium‑Ion Batteries

Na_(3)V_(2)(PO_(4))_(3)(NVP)has garnered great attentions as a prospective cathode material for sodium-ion batteries(SIBs)by virtue of its decent theoretical capacity,superior ion conductivity and high structural stability.However,the inherently poor electronic conductivity and sluggish sodium-ion diffusion kinetics of NVP material give rise to inferior rate performance and unsatisfactory energy density,which strictly confine its further application in SIBs.Thus,it is of significance to boost the sodium storage performance of NVP cathode material.Up to now,many methods have been developed to optimize the electrochemical performance of NVP cathode material.In this review,the latest advances in optimization strategies for improving the electrochemical performance of NVP cathode material are well summarized and discussed,including carbon coating or modification,foreign-ion doping or substitution and nanostructure and morphology design.The foreign-ion doping or substitution is highlighted,involving Na,V,and PO_(4)^(3−)sites,which include single-site doping,multiple-site doping,single-ion doping,multiple-ion doping and so on.Furthermore,the challenges and prospects of high-performance NVP cathode material are also put forward.It is believed that this review can provide a useful reference for designing and developing high-performance NVP cathode material toward the large-scale application in SIBs.

Recent progress in flexible sensors based on 2D materials

With the rapid development of the internet of things(IoT)and wearable electronics,the role of flexible sensors is becoming increasingly irreplaceable,due to their ability to process and convert information acquisition.Two-dimensional(2D)materials have been widely welcomed by researchers as sensitive layers,which broadens the range and application of flexible sensors due to the advantages of their large specific surface area,tunable energy bands,controllable thickness at the atomic level,stable mechanical properties,and excellent optoelectronic properties.This review focuses on five different types of 2D materials for monitoring pressure,humidity,sound,gas,and so on,to realize the recognition and conversion of human body and environmental signals.Meanwhile,the main problems and possible solutions of flexible sensors based on 2D materials as sensitive layers are summarized.

Recent Advances in In-Memory Computing:Exploring Memristor and Memtransistor Arrays with 2D Materials

The conventional computing architecture faces substantial chal-lenges,including high latency and energy consumption between memory and processing units.In response,in-memory computing has emerged as a promising alternative architecture,enabling computing operations within memory arrays to overcome these limitations.Memristive devices have gained significant attention as key components for in-memory computing due to their high-density arrays,rapid response times,and ability to emulate biological synapses.Among these devices,two-dimensional(2D)material-based memristor and memtransistor arrays have emerged as particularly promising candidates for next-generation in-memory computing,thanks to their exceptional performance driven by the unique properties of 2D materials,such as layered structures,mechanical flexibility,and the capability to form heterojunctions.This review delves into the state-of-the-art research on 2D material-based memristive arrays,encompassing critical aspects such as material selection,device perfor-mance metrics,array structures,and potential applications.Furthermore,it provides a comprehensive overview of the current challenges and limitations associated with these arrays,along with potential solutions.The primary objective of this review is to serve as a significant milestone in realizing next-generation in-memory computing utilizing 2D materials and bridge the gap from single-device characterization to array-level and system-level implementations of neuromorphic computing,leveraging the potential of 2D material-based memristive devices.

Cu-Based Materials for Enhanced C_(2+) Product Selectivity in Photo-/Electro-Catalytic CO_(2) Reduction: Challenges and Prospects

Carbon dioxide conversion into valuable products using photocatalysis and electrocatalysis is an effective approach to mitigate global environmental issues and the energy shortages. Among the materials utilized for catalytic reduction of CO_(2), Cu-based materials are highly advantageous owing to their widespread availability, cost-effectiveness, and environmental sustainability. Furthermore, Cu-based materials demonstrate interesting abilities in the adsorption and activation of carbon dioxide, allowing the formation of C_(2+) compounds through C–C coupling process. Herein, the basic principles of photocatalytic CO_(2) reduction reactions(PCO_(2)RR) and electrocatalytic CO_(2) reduction reaction(ECO_(2)RR) and the pathways for the generation C_(2+) products are introduced. This review categorizes Cu-based materials into different groups including Cu metal, Cu oxides, Cu alloys, and Cu SACs, Cu heterojunctions based on their catalytic applications. The relationship between the Cu surfaces and their efficiency in both PCO_(2)RR and ECO_(2)RR is emphasized. Through a review of recent studies on PCO_(2)RR and ECO_(2)RR using Cu-based catalysts, the focus is on understanding the underlying reasons for the enhanced selectivity toward C_(2+) products. Finally, the opportunities and challenges associated with Cu-based materials in the CO_(2) catalytic reduction applications are presented, along with research directions that can guide for the design of highly active and selective Cu-based materials for CO_(2) reduction processes in the future.

MXenes: Versatile 2D materials with tailored surface chemistry and diverse applications

MXenes,the most recent addition to the 2D material family,have attracted significant attention owing to their distinctive characteristics,including high surface area,conductivity,surface characteristics,mechanical strength,etc.This review begins by presenting MXenes,providing insights into their structural characteristics,synthesis methods,and surface functional groups.The review covers a thorough analysis of MXene surface properties,including surface chemistry and termination group impacts.The properties of MXenes are influenced by their synthesis,which can be fluorine-based or fluorinedependent.Fluorine-based synthesis techniques involve etching with fluorine-based reagents,mainly including HF or LiF/HCl,while fluorine-free methods include electrochemical etching,chemical vapor deposition(CVD),alkaline etching,Lewis acid-based etching,etc.These techniques result in the emergence of functional groups such as-F,-O,-OH,-Cl,etc.on the MXenes surface,depending on the synthesis method used.Properties of MXenes,such as electrical conductivity,electronic properties,catalytic activity,magnetic properties,mechanical strength,and chemical and thermal stability,are examined,and the role of functional groups in determining these properties is explored.The review delves into the diverse applications of MXenes,encompassing supercapacitors,battery materials,hydrogen storage,fuel cells,electromagnetic interference(EMI) shielding,pollutant removal,water purification,flexible electronics,sensors,additive manufacturing,catalysis,biomedical and healthcare fields,etc.Finally,this article outlines the challenges and opportunities in the current and future development of MXenes research,addressing various aspects such as synthesis scalability,etching challenges,and multifunctionality,and exploring novel applications.The review concludes with future prospects and conclusions envisioning the impact of MXenes on future technologies and innovation.

Realizing High Thermoelectric Performance in n-Type Se-Free Bi_(2)Te_(3)Materials by Spontaneous Incorporation of FeTe_(2)Nanoinclusions

Bi_(2)Te_(3)-based materials have drawn much attention from the thermoelectric community due to their excellent thermoelectric performance near room temperature.However,the stability of existing n-type Bi_(2)(Te,Se)_(3)materials is still low due to the evaporation energy of Se(37.70 kJ mol^(-1))being much lower than that of Te(52.55 kJ mol^(-1)).The evaporated Se from the material causes problems in interconnects of the module while degrading the efficiency.Here,we have developed a new approach for the high-performance and stable n-type Se-free Bi_(2)Te_(3)-based materials bymaximizing the electronic transport while suppressing the phonon transport,at the same time.Spontaneously generated FeTe_(2)nanoinclusions within the matrix during the melt-spinning and subsequent spark plasma sintering is the key to simultaneous engineering of the power factor and lattice thermal conductivity.The nanoinclusions change the fermi level of the matrix while intensifying the phonon scattering via nanoparticles.With a fine-tuning of the fermi level with Cu doping in the n-type Bi_(2)Te_(3)-0.02FeTe_(2),a high power factor of∼41×10^(-4)Wm^(-1)K^(-2)with an average zT of 1.01 at the temperature range 300-470 K are achieved,which are comparable to those obtained in n-type Bi_(2)(Te,Se)_(3)materials.The proposed approach enables the fabrication of high-performance n-type Bi_(2)Te_(3)-based materials without having to include volatile Se element,which guarantees the stability of the material.Consequently,widespread application of thermoelectric devices utilizing the n-type Bi_(2)Te_(3)-based materials will become possible.

Electronic properties of 2D materials and their junctions

With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2D materials,knowledge of 2D electrical transport and carrier dynamics still in its infancy.Thus,here we highlighted the electrical characteristics of 2D materials with electronic band structure,electronic transport,dielectric constant,carriers mobility.The atomic thinness of 2D materials makes substantially scaled field-effect transistors(FETs)with reduced short-channel effects conceivable,even though strong carrier mobility required for high performance,low-voltage device operations.We also discussed here about factors affecting 2D materials which easily enhanced the activity of those materials for various applications.Presently,Those 2D materials used in state-of-the-art electrical and optoelectronic devices because of the extensive nature of their electronic band structure.2D materials offer unprecedented freedom for the design of novel p-n junction device topologies in contrast to conventional bulk semiconductors.We also,describe the numerous 2D p-n junctions,such as homo junction and hetero junction including mixed dimensional junctions.Finally,we talked about the problems and potential for the future.

Polypyrrole-coated triple-layer yolk-shell Fe_(2)O_(3)anode materials with their superior overall performance in lithium-ion batteries

Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life.In this work,an ap-proach is pioneered for preparing high-performance Fe_(2)O_(3)anode materials,by innovatively synthesizing a triple-layer yolk-shell Fe_(2)O_(3)uniformly coated with a conductive polypyrrole(Ppy)layer(Fe_(2)O_(3)@Ppy-TLY).The uniform polypyrrole coating introduces more reac-tion sites and adsorption sites,and maintains structure stability through charge-discharge process.In the uses as lithium-ion battery elec-trodes,Fe_(2)O_(3)@Ppy-TLY demonstrates high reversible specific capacity(maintaining a discharge capacity of 1375.11 mAh·g^(−1)after 500 cycles at 1 C),exceptional cycling stability(retaining the steady charge-discharge performance at 544.33 mAh·g^(−1)after 6000 ultrafast charge-discharge cycles at a 10 C current density),and outstanding high current charge-discharge performance(retaining a reversible ca-pacity of 156.75 mAh·g^(−1)after 10000 cycles at 15 C),thereby exhibiting superior lithium storage performance.This work introduces in-novative advancements for Fe_(2)O_(3)anode design,aiming to enhance its performance in energy storage fields.

Review and prospects on the low-voltage Na_(2)Ti_(3)O_(7) anode materials for sodium-ion batteries

Due to its low cost and natural abundance of sodium,Na-ion batteries(NIBs)are promising candidates for large-scale energy storage systems.The development of ultralow voltage anode materials is of great significance in improving the energy density of NIBs.Low-voltage anode materials,however,are severely lacking in NIBs.Of all the reported insertion oxides anodes,the Na_(2)Ti_(3)O_(7) has the lowest operating voltage(an average potential of 0.3 V vs.Na^(+)/Na)and is less likely to deposit sodium,which has excellent potential for achieving NIBs with high energy densities and high safety.Although significant progress has been made,achieving Na_(2)Ti_(3)O_(7) electrodes with excellent performance remains a severe challenge.This paper systematically summarizes and discusses the physicochemical properties and synthesis methods of Na_(2)Ti_(3)O_(7).Then,the sodium storage mechanisms,key issues and challenges,and the optimization strategies for the electrochemical performance of Na_(2)Ti_(3)O_(7) are classified and further elaborated.Finally,remaining challenges and future research directions on the Na_(2)Ti_(3)O_(7) anode are highlighted.This review offers insights into the design of high-energy and high-safety NIBs.

Arc erosion behaviors of AgSnO_2 contact materials prepared with different SnO_2 particle sizes

To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallurgy. The microstructure of Ag?4%SnO2 contact materials was characterized, and the relative density, hardness and electrical conductivity were measured. The arc erosion of Ag?4%SnO2 contact materials was tested, the arc duration and mass loss before and after arc erosion were determined, the surface morphologies and compositions of Ag?4%SnO2 contact materials after arc erosion were characterized, and the arc erosion mechanism of AgSnO2 contact materials was discussed. The results show that fine SnO2 particle is beneficial for the improvement of the relative density and hardness, but decreases the electrical conductivity. With the decrease of SnO2 particle size, Ag?4%SnO2contact material presents shorter arc duration, less mass loss, larger erosion area and shallower arc erosion pits.

Influences of transition metal on structural and electrochemical properties of Li[Ni_xCo_yMn_z]O_2(0.6≤x≤0.8) cathode materials for lithium-ion batteries

Li[NixCoyMn2]O2（0.6≤x≤0.8） cathode materials with a typical hexagonal α-NaFeO2 structure were prepared utilizing a co-precipitation method.It is found that the ratio of peak intensities of（003） to（104） observed from X-ray diffraction（XRD）increases with decreasing the Ni content or increasing the Co content.The scanning electron microscopy（SEM） images reveal that the small primary particles are agglomerated to form the secondary ones.As the Mn content increases,the primary and secondary particles become larger and the resulted particle size for the Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 is uniformly distributed in the range of100-300 nm.Although the initial discharge capacity of the Li/Li[NixCoyMn2]O2 cells reduces with decreasing the Ni content,the cyclic performance and rate capability are improved with higher Mn or Co content.The Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 can deliver excellent cyclability with a capacity retention of 97.1%after 50 cycles.

Effects of current density on preparation and performance of Al/conductive coating/α-PbO_2-Ce O_2-TiO_2/β-Pb O_2-MnO_2-WC-ZrO_2 composite electrode materials

Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy（EDXS）, anode polarization curves, quasi-stationary polarization（Tafel） curves, electrochemical impedance spectroscopy（EIS）, scanning electron microscopy（SEM）, and X-ray diffraction（XRD）. Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential（0.610 V at 500 A/m2） for oxygen evolution, the best electrocatalytic activity, the longest service life（360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2）, and the lowest cell voltage（2.75 V at 500 A/m2）. Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.

Effect of Carbon Dioxide (CO_2) Controlled Atmosphere on Superoxide Dismutase (SOD) Activity of Three Storage Pests in Chinese Medicinal Materials

[ Objective ] The paper was to study the effect of controlled atmosphere stress of carbon dioxide （ CO2 ） on Superoxide dismutase （SOD） activity of in- sect, so as to analyze the biological mechanism of the action of controlled atmosphere stress on insect. [ Method] Using nitrotetrazolium blue chloride （NBT） light reduction method, SOD activity of drugstore beetle （ Stegobium panlceum ）, cigarette beetle （ Lasioderma serricorne） and coffee bean beetle （Araecerus fasciculatus） was studied, and the stress response of the enzyme under controlled atmosphere stress of CO2 was analyzed. [ Result ] SOD activity of drugstore beetle, cigarette beetle and coffee bean beetle exposed to controlled atmosphere stress of high concentrations of CO2 for 3 and 6 h had certain degree of increase, and the activity sig- nificantly increased from 2.011±0.954,2.664±0.218 and 1.458±0.718 to 3. 135±0. 105,3.050±0.673 and 2.975±0.229 U/（per pest · 30 min） after treat- ment for 6 h. [ Conclusion] Controlled atmosphere stress of high concentrations of CO2 had certain activation effect on SOD activity of storage pest in Chinese me- dicinal material within the context of sub-lethal events. The results could enrich the insecticidal mechanism of controlled atmosphere and theoretical system of analy- sis on insect resistance to controlled atmosphere.

Difficulties, strategies, and recent research and development of layered sodium transition metal oxide cathode materials for high-energy sodium-ion batteries

Energy-storage systems and their production have attracted significant interest for practical applications.Batteries are the foundation of sustainable energy sources for electric vehicles(EVs),portable electronic devices(PEDs),etc.In recent decades,Lithium-ion batteries(LIBs) have been extensively utilized in largescale energy storage devices owing to their long cycle life and high energy density.However,the high cost and limited availability of Li are the two main obstacles for LIBs.In this regard,sodium-ion batteries(SIBs) are attractive alternatives to LIBs for large-scale energy storage systems because of the abundance and low cost of sodium materials.Cathode is one of the most important components in the battery,which limits cost and performance of a battery.Among the classified cathode structures,layered structure materials have attracted attention because of their high ionic conductivity,fast diffusion rate,and high specific capacity.Here,we present a comprehensive review of the classification of layered structures and the preparation of layered materials.Furthermore,the review article discusses extensively about the issues of the layered materials,namely(1) electrochemical degradation,(2) irreversible structural changes,and(3) structural instability,and also it provides strategies to overcome the issues such as elemental phase composition,a small amount of elemental doping,structural design,and surface alteration for emerging SIBs.In addition,the article discusses about the recent research development on layered unary,binary,ternary,quaternary,quinary,and senary-based O3-and P2-type cathode materials for high-energy SIBs.This review article provides useful information for the development of high-energy layered sodium transition metal oxide P2 and O3-cathode materials for practical SIBs.

2D multifunctional devices:from material preparation to device fabrication and neuromorphic applications

Neuromorphic computing systems,which mimic the operation of neurons and synapses in the human brain,are seen as an appealing next-generation computing method due to their strong and efficient computing abilities.Two-dimensional (2D) materials with dangling bond-free surfaces and atomic-level thicknesses have emerged as promising candidates for neuromorphic computing hardware.As a result,2D neuromorphic devices may provide an ideal platform for developing multifunctional neuromorphic applications.Here,we review the recent neuromorphic devices based on 2D material and their multifunctional applications.The synthesis and next micro–nano fabrication methods of 2D materials and their heterostructures are first introduced.The recent advances of neuromorphic 2D devices are discussed in detail using different operating principles.More importantly,we present a review of emerging multifunctional neuromorphic applications,including neuromorphic visual,auditory,tactile,and nociceptive systems based on 2D devices.In the end,we discuss the problems and methods for 2D neuromorphic device developments in the future.This paper will give insights into designing 2D neuromorphic devices and applying them to the future neuromorphic systems.

Exploring the potential of olivine-containing copper-nickel slag for carbon dioxide mineralization in cementitious materials

Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementitious material(CNCM)was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO_(2) mineralization capacity.Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development.Meanwhile,thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO_(2) adsorption amount and carbonation products of CNCM.Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging(BSE)with energy-dispersive X-ray spectrometry.Results showed that among the studied samples,the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO_(2) sequestration amount of 8.51wt%at 80℃and 72 h while presenting the compressive strength of 39.07 MPa.This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO_(2) and exhibit high compressive strength.Although the addition of citric acid did not improve strength development,it was beneficial to increase the CO_(2) diffusion and adsorption amount under the same carbonation conditions from BSE results.This work provides guidance for synthesizing CO_(2)-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals.

Microwave synthesis of Li_2FeSiO_4 cathode materials for lithium-ion batteries

A novel synthetic method of microwave processing to prepare Li2FeSiO4 cathode materials is adopted. The Li2FeSiO4 cathode material is prepared by mechanical ball-milling and subsequent microwave processing. Olivin-type Li2FeSiO4 sample with uniform and fine particle sizes is successfully and fast synthesized by microwave heating at 700 ℃ in 12 rain. And the obtained Li2FeSiO4 materials show better electrochemical performance and microstructure than those of Li2FeSiO4 sample by the conventional solidstate reaction. ？2009 Yan Bing Cao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Room-Temperature Gas Sensors Under Photoactivation:From Metal Oxides to 2D Materials

Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap,low power consumption and portable sensors for rapidly growing Internet of things applications.As an important approach,light illumination has been exploited for room-temperature operation with improving gas sensor's attributes including sensitivity,speed and selectivity.This review provides an overview of the utilization of photoactivated nanomaterials in gas sensing field.First,recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are highlighted.Later,excellent gas sensing performance of emerging two-dimensional materialsbased sensors under light illumination is discussed in details with proposed gas sensing mechanism.Originated impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing characteristics.Finally,the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications.

Microstructure and properties of Ag–Ti_3SiC_2 contact materials prepared by pressureless sintering

Ti3SiC2-reintbrced Ag-maJxix composites are expected to serve as eleclrical contacts. In this study, the wettability of Ag on a Ti3SiC2 subslxate was measured by the sessile drop melkod. The Ag-Ti3SiC2 composites were prepared from Ag mad Ti3SiC2 powder mix- tures by pressureless sintering. The effects of compacting pressure （100-800 MPa）, sintering temperature （850-950~C）, mad soaking time （0.5-2 h） on the microslxucture mad properties of the Ag-Ti3SiC2 composites were investigated. The experimental results indicated that Ti3SiC2 paxticulates were uniformly distxibuted in flae Ag matrix, wiflaout reactions at the interthces between flae two phases. The prepared Ag-10wt%Ti3SiC2 had a relative density of 95% mad an electrical resistivity of 2.76 x 10 3 m~）＇cm when compacted at 800 MPa mad sintered at 950~C for 1 h. The incorporation of Ti3SiC2 into Ag was found to improve its hardness without substantially compromising its electrical conductivity; INs behavior was attxibuted to the combination of ceramic and metallic properties of the Ti3SiC2 reinforcement, suggesting its potential application in electrical contacts.