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.

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.

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.

2D Materials Boost Advanced Zn Anodes:Principles,Advances,and Challenges

Aqueous zinc-ion battery(ZIB)featuring with high safety,low cost,environmentally friendly,and high energy density is one of the most promising systems for large-scale energy storage application.Despite extensive research progress made in developing high-performance cathodes,the Zn anode issues,such as Zn dendrites,corrosion,and hydrogen evolution,have been observed to shorten ZIB’s lifespan seriously,thus restricting their practical application.Engineering advanced Zn anodes based on two-dimensional(2D)materials are widely investigated to address these issues.With atomic thickness,2D materials possess ultrahigh specific surface area,much exposed active sites,superior mechanical strength and flexibility,and unique electrical properties,which confirm to be a promising alternative anode material for ZIBs.This review aims to boost rational design strategies of 2D materials for practical application of ZIB by combining the fundamental principle and research progress.Firstly,the fundamental principles of 2D materials against the drawbacks of Zn anode are introduced.Then,the designed strategies of several typical 2D materials for stable Zn anodes are comprehensively summarized.Finally,perspectives on the future development of advanced Zn anodes by taking advantage of these unique properties of 2D materials are proposed.

Recent advances in the mechanics of 2D materials

The exceptional physical properties and unique layered structure of two-dimensional(2D)materials have made this class of materials great candidates for applications in electronics,energy conversion/storage devices,nanocomposites,and multifunctional coatings,among others.At the center of this application space,mechanical properties play a vital role in materials design,manufacturing,integration and performance.The emergence of 2D materials has also sparked broad scientific inquiry,with new understanding of mechanical interactions between 2D structures and interfaces being of great interest to the community.Building on the dramatic expansion of recent research activities,here we review significant advances in the understanding of the elastic properties,in-plane failures,fatigue performance,interfacial shear/friction,and adhesion behavior of 2D materials.In this article,special emphasis is placed on some new 2D materials,novel characterization techniques and computational methods,as well as insights into deformation and failure mechanisms.A deep understanding of the intrinsic and extrinsic factors that govern 2D material mechanics is further provided,in the hopes that the community may draw design strategies for structural and interfacial engineering of 2D material systems.We end this review article with a discussion of our perspective on the state of the field and outlook on areas for future research directions.

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.

2D materials modulating layered double hydroxides for electrocatalytic water splitting

Exploring highly efficient electrochemical water splitting catalysts has recently attracted extensive research interest from both fundamental researches and practical applications.Transition metal‐based layered double hydroxides(LDHs)have been proved to be one of the most efficient materials for oxygen evolution reaction(OER),however,still suffered from low conductivity and sluggish kinetics for hydrogen evolution reaction(HER),which largely inhibited the overall water splitting efficiency.To address this dilemma,enormous approaches including doping regulation,intercalation tuning and defect engineering are therefore rationally designed and developed.Herein,we focus on the recent exciting progress of LDHs hybridization with other two‐dimensional(2D)materials for water splitting reactions,not barely for enhancing OER efficiency but also for boosting HER activity.Particularly,the structural features,morphologies,charge transfer and synergistic effects for the heterostructure/heterointerface that influence the electrocatalytic performance are discussed in details.The hybrid 2D building blocks not only serve as additional conductivity and structural supported but also promote electron transfer at the interfaces and further enhance the electrocatalytic performance.The construction and application of the nanohybrid materials will guide a new direction in developing multifunctional materials based on LDHs,which will contribute to energy conversion and storage.

Recent advances in graphene and other 2D materials

The isolation of the first two-dimensional material, graphene-a monolayer of carbon atoms arranged in a hexagonal lattice-opened new exciting opportunities in the field of condensed matter physics and materials. Its isolation and subsequent studies demonstrated that it was possible to obtain sheets of atomically thin crystals and that these were stable, and they also began to show its outstanding properties, thus opening the door to a whole new family of materials, known as two-dimensional materials or 2D materials. The great interest in different 2D materials is motivated by the variety of properties they show, being candidates for numerous applications.Additionally, the combination of 2D crystals allows the assembly of composite, on-demand materials, known as van der Waals heterostructures, which take advantage of the properties of those materials to create functionalities that otherwise would not be accessible. For example, the combination of 2D materials, which can be done with high precision, is opening up opportunities for the study of new challenges in fundamental physics and novel applications. Here we review the latest fundamental discoveries in the area of 2D materials and offer a perspective on the future of the field.

Recent progress in 2D materials for flexible supercapacitors

High performance supercapacitors coupled with mechanical flexibility are needed to drive flexible and wearable electronics that have anesthetic appeal and multi-functionality. Two dimensional（2D） materials have attracted attention owing to their unique physicochemical and electrochemical properties, in addition to their ability to form hetero-structures with other nanomaterials further improving mechanical and electrochemical properties. After a brief introduction of supercapacitors and 2D materials, recent progress on flexible supercapacitors using 2D materials is reviewed. Here we provide insights into the structure–property relationships of flexible electrodes, in particular free-standing films. We also present our perspectives on the development of flexible supercapacitors.

Recent progress in solution assembly of 2D materials for wearable energy storage applications

Wearable energy storage devices are desirable to boost the rapid development of flexible and stretchable electronics. Two-dimensional (2D) materials, e.g., graphene, transition metal dichalcogenides and oxides, and MXenes, have attracted intensive attention for flexible energy storage applications because of their ultrathin 2D structures, high surface-to-volume ratio, and unique physical/chemical properties. To achieve commercialization of 2D material-based wearable energy storage devices (2DM-WESDs), scalable and cost-efficient manufacturing is a critical challenge. Among existing manufacturing technologies, solution-based assembly strategies show strong potential to achieve low-cost and scalable production. A timely review of the recent progress in solution-based assembly strategies and the resultant 2DM-WESDs will be meaningful to guide the future development of 2DM-WESDs. In this review, first, a brief introduction of exfoliation and solution preparation of 2D material species from bulk materials is discussed. Then, the solution-based assembly strategies are summarized, and the advantages and disadvantages of each method are compared. After that, two major categories of 2DM-WESDs, supercapacitor and battery, are discussed, emphasizing their state-of-the-art energy storage performances and flexibilities. Finally, insights and perspectives on current challenges and future opportunities regarding the solution assembly of 2DM-WESDs are discussed.

Self-limiting laser crystallization and direct writing of 2D materials

Direct growth and patterning of atomically thin two-dimensional(2D)materials on various substrates are essential steps towards enabling their potential for use in the next generation of electronic and optoelectronic devices.The conventional gas-phase growth techniques,however,are not compatible with direct patterning processes.Similarly,the condensed-phase methods,based on metal oxide deposition and chalcogenization processes,require lengthy processing times and high temperatures.Here,a novel self-limiting laser crystallization process for direct crystallization and patterning of 2D materials is demonstrated.It takes advantage of significant differences between the optical properties of the amorphous and crystalline phases.Pulsed laser deposition is used to deposit a thin layer of stoichiometric amorphous molybdenum disulfide(MoS2)film(∼3 nm)onto the fused silica substrates.A tunable nanosecond infrared(IR)laser(1064 nm)is then employed to couple a precise amount of power and number of pulses into the amorphous materials for controlled crystallization and direct writing processes.The IR laser interaction with the amorphous layer results in fast heating,crystallization,and/or evaporation of the materials within a narrow processing window.However,reduction of the midgap and defect states in the as crystallized layers decreases the laser coupling efficiency leading to higher tolerance to process parameters.The deliberate design of such laser 2D material interactions allows the selflimiting crystallization phenomena to occur with increased quality and a much broader processing window.This unique laser processing approach allows high-quality crystallization,direct writing,patterning,and the integration of various 2D materials into future functional devices.

Light–matter interaction of 2D materials:Physics and device applications

In the last decade, the rise of two-dimensional （2D） materials has attracted a tremendous amount of interest for the entire field of photonics and opto-electronics. The mechanism of light-matter interaction in 2D materials challenges the knowledge of materials physics, which drives the rapid development of materials synthesis and device applications. 2D materials coupled with plasmonic effects show impressive optical characteristics, involving efficient charge transfer, plas- monic hot electrons doping, enhanced light-emitting, and ultrasensitive photodetection. Here, we briefly review the recent remarkable progress of 2D materials, mainly on graphene and transition metal dichalcogenides, focusing on their tunable optical properties and improved opto-electronic devices with plasmonic effects. The mechanism of plasmon enhanced light-matter interaction in 2D materials is elaborated in detail, and the state-of-the-art of device applications is compre- hensively described. In the future, the field of 2D materials holds great promise as an important platform for materials science and opto-electronic engineering, enabling an emerging interdisciplinary research field spanning from clean energy to information technology.

Harnessing the Unique Features of 2D Materials toward Dendrite-free Metal Anodes

Electrochemically active metal anodes,such as lithium,sodium,potassium,and zinc,have attracted great research interests in the advanced rechargeable batteries owing to their superior theoretical energy densities.Unfortunately,the metal anodes suffer from the huge volume changes with loss of active materials during the plating and stripping processes,resulting in fast capacity decay.Moreover,the random growth of dendrites on the metal anodes will penetrate the separator,causing severe safety issues.Engineering metal anodes by introducing the 2D materials are widely investigated to alleviate these issues.Benefitting from the ultrathin structure feature and unique electrical properties,2D materials are regarded as one of the best host of metal anodes.Besides,the tunable active sites on basal plane enable 2D materials to achieve favorable interaction with metal anodes.Moreover,some 2D materials exhibit good mechanical strength and flexibility,serving as building block for the artificial solid electrolyte interphase.In this review,we mainly disclosed the correlations between the intrinsic properties of 2D materials and their functions in guiding uniform nucleation,controlling the growth of metals,and accommodating the volume change.Also,the challenges of 2D materials in metal anodes are well discussed.Finally,the future directions to develop highperformance metal anodes by taking advantage of these unique features of 2D materials are proposed.

State of the Art in Alcohol Sensing with 2D Materials

Since the discovery of graphene,the star among new materials,there has been a surge of attention focused on the monatomic and monomolecular sheets which can be obtained by exfoliation of layered compounds.Such materials are known as two-dimensional(2D)materials and offer enormous versatility and potential.The ultimate single atom,or molecule,thickness of the 2D materials sheets provides the highest surface to weight ratio of all the nanomaterials,which opens the door to the design of more sensitive and reliable chemical sensors.The variety of properties and the possibility of tuning the chemical and surface properties of the 2D materials increase their potential as selective sensors,targeting chemical species that were previously difficult to detect.The planar structure and the mechanical flexibility of the sheets allow new sensor designs and put 2D materials at the forefront of all the candidates for wearable applications.When developing sensors for alcohol,the response time is an essential factor for many industrial and forensic applications,particularly when it comes to hand-held devices.Here,we review recent developments in the applications of 2D materials in sensing alcohols along with a study on parameters that affect the sensing capabilities.The review also discusses the strategies used to develop the sensor along with their mechanisms of sensing and provides a critique of the current limitations of 2D materials-based alcohol sensors and an outlook for the future research required to overcome the challenges.

Preface to Special Topic:Graphene and 2D Materials for Energy Storage

Graphene, a single layer of graphite, has been one of the first real two dimensional （2D） materials isolated in 2004. Thus, graphene is becoming a cutting edge material that opens up new horizons to a whole family of 2D materials beyond the limited current applicability of graphene. The unique advantages of graphene and analogue 2D materials, such as atomic-scale thickness, high specific surface area, mechanically flexible robustness, superior storage capacity, endow them as high-performance electrodes lbr electrochemical energy storage devices. Although it is hard to say whether or not graphene and 2D materials will be implemented in future energy technologies, the recent achievements in this field demonstrate that their roles will be noticeable in the near future.

2D Materials as Protective Coating against Low and Middle Temperature (100°C - 300°C) Corrosion-Erosion in Waste to Energy Plant: Case of Graphene

The combustion of MSW contains several species which if liberated into the flue gas will participate in erosion-corrosion reactions with the alloy surface and with the oxide layers. Actually with the evolution of material science and the discovery of 2D materials, we can handle that situation as well as possible. The graphene as 2D material presents a lot of advantage due to it physical properties such: melting point, boiling point and thermal conductivity, which can help to manage the problem of low and middle temperature (100°C - 300°C) erosion-corrosion into the boiler wall of waste to energy. The aim of the study was focused on analyzing the resistance at low and middle temperature (100°C - 300°C) in the enclosed environment and the corrosion-erosion resistance abilities of the graphene sheet as the 2D protective coating material. This paper analyzed the possibility of using the graphene in the aggressive environment which is waste to energy boiler. The results obtained from this study after simulation using ANSYS software which is one of the best software for simulations showed that Graphene protects the furnace walls against corrosion-erosion for temperatures lower than 400°C and that in the presence of certain impurities such as: sodium (Na), sulfur (S), chloride (Cl) and Phos- phorous (P), Sodium Chloride (NaCl), Hydrogen Chloride (HCl), Dioxide of Carbone (CO2) and Dioxide of Sulfur (SO2).

Recent Progress in the Fabrication, Properties, and Devices of Heterostructures Based on 2D Materials

With a large number of researches being conducted on two?dimen?sional(2D) materials, their unique properties in optics, electrics, mechanics, and magnetics have attracted increasing attention. Accordingly, the idea of combining distinct functional 2D materials into heterostructures naturally emerged that pro?vides unprecedented platforms for exploring new physics that are not accessible in a single 2D material or 3D heterostructures. Along with the rapid development of controllable, scalable, and programmed synthesis techniques of high?quality 2D heterostructures, various heterostructure devices with extraordinary performance have been designed and fabricated, including tunneling transistors, photodetectors, and spintronic devices. In this review, we present a summary of the latest progresses in fabrications, properties, and applications of di erent types of 2D heterostruc?tures, followed by the discussions on present challenges and perspectives of further investigations.

Advance in reversible Zn anodes promoted by 2D materials

With the growing energy demand associated with high safety and low-cost requirement,aqueous zinc-ion batteries(AZIBs)have been considered as one of the most promising next-generation batteries.However,some key issues,such as uncontrollable dendrites growth,severe corrosion,hydrogen evolution and side reactions of Zn anodes during charge/discharge process,have hindered its pragmatic applications.Two-dimensional(2D)materials hold advantages of unique physical and chemical properties,large surface areas and abundant active sites,which have been successfully used to overcome the above shortcomings of Zn anodes in recent years.In this review,the issues and challenges of Zn anodes are outlined.Then,the state-of-the-art progress on Zn anodes modification based on 2D materials such as graphene,2D metal carbides and nitrides(MXenes),2D metal-organic frameworks(MOFs),2D covalent organic frameworks(COFs),2D transition metal compounds and other 2D materials is discussed in detail.Finally,the perspectives of employing 2D materials in highly reversible Zn anodes are summarized and discussed.

Exfoliation and Engineering of 2D Materials Through Electrochemistry

Two-dimensional(2D)materials offer countless possibilities for next-generation(opto)electronic devices because of their diverse and tailorable physicochemical characteristics.To bridge the gap between fundamental science and practical applications,simple-to-use universal approaches are essential for the mass production of 2D materials with specific target properties.Electrochemical intercalation/exfoliation stands out from many up-scalable synthetic strategies,thanks to its great time efficiency,mild working conditions,and simple instrumentation.Besides the use for direct exfoliation of 2D materials,device-level controllable intercalation of guest species often results in rich phase diagrams with competing orders and ground states in 2D systems,giving rise to new exotic quantum phenomena.Therefore,making use of electrochemistry in ion intercalation and host–guest interaction is crucial to expand the library,as well as the function of 2D materials.Here,we present a focused review of the exciting advances of electrochemical exfoliation and engineering of 2D materials,including intercalation strategies,intercalation chemistry,exfoliation mechanisms,material properties,and potential applications.An outlook on the major challenges and perspectives is also presented at the end of the discussion.