2D Nanomaterials for Effective Energy Scavenging

The development of a nation is deeply related to its energy consumption.2D nanomaterials have become a spotlight for energy harvesting applications from the small-scale of low-power electronics to a large-scale for industry-level applications,such as self-powered sensor devices,environmental monitoring,and large-scale power generation.Scientists from around the world are working to utilize their engrossing properties to overcome the challenges in material selection and fabrication technologies for compact energy scavenging devices to replace batteries and traditional power sources.In this review,the variety of techniques for scavenging energies from sustainable sources such as solar,air,waste heat,and surrounding mechanical forces are discussed that exploit the fascinating properties of 2D nanomaterials.In addition,practical applications of these fabricated power generating devices and their performance as an alternative to conventional power supplies are discussed with the future pertinence to solve the energy problems in various fields and applications.

Nano-bio interactions between 2D nanomaterials and mononuclear phagocyte system cells

Two-dimensional(2D)nanomaterials,known for their unique atomic arrangements and exceptional physicochemical properties,have garnered significant attention in biomedical applications,particularly in the realms of immunotherapy for tissue engineering and tumor therapy.These applications necessitate a thorough assessment of the potential influence of 2D nanomaterials on immune cells.Notably,the mononuclear phagocyte system(MPS)cells,which play pivotal roles in both innate and adaptive immunity,are essential for maintaining organismal homeostasis.MPS cells with phagocytic capability contribute to the prevention of foreign body invasion and the elimination of dead or senescent cells.Furthermore,MPS cells,including macrophages and dendritic cells,serve as vital bridges between innate and adaptive immune responses.Therefore,understanding the nano-bio interactions between 2D nanomaterials and MPS cells is imperative.These nano-bio interactions including cellular uptake,cytocompatibility,and immunological impact are invaluable forthe purposeful design of 2D nanomaterials.Herein,we provide an overview of the latest advancements in understanding the nano-bio interactions between 2D nanomaterials and MPS cells,and discuss the current challenges and future prospects of employing 2D nanomaterials in the field of nanomedicine.

Revisiting traditional and modern trends in versatile 2D nanomaterials: Synthetic strategies, structural stability, and gas-sensing fundamentals

Two-dimensional nanomaterials(2DNMs)have attracted significant research interest due to their outstanding structural properties,which include unique electrical nanostructures,large surface areas,and high surface reactivity.These adaptable materials have outstanding physicochemical characteristics,making them useful in a variety of applications such as gas-sensing,electronics,energy storage,and catalysis.Extensive research has been conducted in the pursuit of high performance room-temperature(RT)gas sensors with good selectivity,high sensitivity,long-term stability,and rapid response/recovery kinetics.Metal oxides,transition metal chalcogenides,MXenes,graphene,phosphorene,and boron nitride have all been discovered as 2DNMs with strong potential for gas sensors.This review presents an in-depth analysis of current advances in 2DNM research.It includes synthetic techniques,structural stabilities,gas-sensing mechanisms,critical performance parameters,and factors influencing gas-sensing capabilities of 2DNMs.Furthermore,the present study emphasizes structural engineering and optimization methodologies that improve gas-sensing performance.It also highlights current challenges and outlines future research directions in the domain of tailoring 2DNMs for advanced RT gas sensors.This systematically designed comprehensive review article aims to provide readers with profound insights into gas detection,thereby inspiring the generation of innovative ideas to develop cutting-edge 2DNMs-based gas sensors.

Surface-enhanced Raman Scattering on 2D Nanomaterials:Recent Developments and Applications

Surface enhanced Raman spectroscopy(SERS)has emerged as a highly powerful and sensitive tool for molecular analysis.Of the various factors that affect SERS performance,substrate material is the most critical.Since first observed in 1974,noble metals have been the most common substrates for SERS.However,their increasing defects including low selectivity,weak uniformity,and poor stability are all obstacles to these noble metal-based SERS substrates.Recently,due to the unique layer-dependent optical properties and a very large surface-to-volume ratio,two-dimensional(2D)nanomaterials are found to be promising candidates to overcome the shortcomings of a conventional metallic SERS sub-strate.Herein,we concentrate on the latest development and applications of SERS-active 2D nano-materials in our group as well as in other related research studies.The enhancement mechanism of the SERS effect and the development of various SERS-active 2D nanomaterials have been discussed in detail.Eventually,the latest development in 2D nanomaterial-SERS based analytical applications from trace detection of small organic pollutants and macromolecular biomarkers to in-situ cytosensing and in-situ theranostic analysis is introduced.

Recent advancements in 2D nanomaterials for cancer therapy

Since mechanical exfoliation of graphene in 2004, unprecedented scientific and technological advances have been achieved in the development of two-dimensional(2 D) nanomaterials. These 2 D nanomaterials exhibit various unique mechanical, physical and chemical properties on account of their ultrathin thickness, which are highly desirable for many applications such as catalysis, optoelectronics, energy storage/conversion, as well as disease diagnosis and therapeutics. In this review, we summarized recent progress on the design and fabrication of functional 2 D nanomaterials capable of being applied for the cancer treatment including drug delivery, photodynamic therapy, and photothermal therapy. Their anticancer mechanisms were discussed in detail, and the related safety concerns were analyzed based on current research developments. This review is expected to provide an insight in the field of 2 D nanostructured materials for anticancer applications.

Engineering lattice defects in 2D nanomaterials for enhancing biomedical performances

2D nanomaterials are widely investigated for biomedical applications,attributed to their large specific surface area,high therapeutic loading capacity,and unique optical,thermal,and/or electronic characteristics.Lattice defects affect the theranostic performance of 2D nanomaterials significantly by altering their electronic properties and chemical binding.Recent investigations have shown that defect-rich 2D nanomaterials are capable of enhancing tumor treatment through efficient drug delivery,photothermal and photodynamic therapies(PTT and PDT),and improving diagnostics via computed tomography(CT),photoacoustic and magnetic resonance imaging.This review summarizes recent progresses,including synthesis,characterization approach,and applications of defect-engineered 2D nanomaterials that are potentially useful in cancer treatment.The expert opinions are also proposed as the conclusion.

2D nanomaterials for tissue engineering application

Recently,tissue engineering has developed into a powerful tool for repairing and reconstructing damaged tissues and organs.Tissue engineering scaffolds play a vital role in tissue engineering,as they not only provide structural support for targeted cells but also serve as templates that guide tissue regeneration and control the tissue structure.Over the past few years,owing to unique physicochemical properties and excellent biocompatibility,various types of two-dimensional(2D)nanomaterials have been developed as candidates for the construction of tissue engineering scaffolds,enabling remarkable achievements in bone repair,wound healing,neural regeneration,and cardiac tissue engineering.These efforts have significantly advanced the development of tissue engineering.In this review,we summarize the latest advancements in the application of 2D nanomaterials in tissue engineering.First,each typical 2D nanomaterial is introduced briefly,followed by a detailed description of its applications in tissue engineering.Finally,the existing challenges and prospects for the future of the application of 2D nanomaterials in tissue engineering are discussed.

MXene-Based Elastomer Mimetic StretchableSensors: Design, Properties, and Applications

Flexible sensors based on MXene-polymer composites are highly prospective for next-generation wearable electronics used in human-machine interfaces.One of the motivating factors behind the progress of flexible sensors is the steady arrival of new conductive materials.MXenes,a new family of 2D nanomaterials,have been draw-ing attention since the last decade due to their high electronic conduc-tivity,processability,mechanical robustness and chemical tunability.In this review,we encompass the fabrication of MXene-based polymeric nanocomposites,their structure-property relationship,and applications in the flexible sensor domain.Moreover,our discussion is not only lim-ited to sensor design,their mechanism,and various modes of sensing platform,but also their future perspective and market throughout the world.With our article,we intend to fortify the bond between flexible matrices and MXenes thus promoting the swift advancement of flexible MXene-sensors for wearable technologies.

Differences and Similarities of Photocatalysis and Electrocatalysis in Two-Dimensional Nanomaterials:Strategies,Traps,Applications and Challenges

Photocatalysis and electrocatalysis have been essential parts of electrochemical processes for over half a century.Recent progress in the controllable synthesis of 2D nanomaterials has exhibited enhanced catalytic performance compared to bulk materials.This has led to significant interest in the exploitation of 2D nanomaterials for catalysis.There have been a variety of excellent reviews on 2D nanomaterials for catalysis,but related issues of differences and similarities between photocatalysis and electrocatalysis in 2D nanomaterials are still vacant.Here,we provide a comprehensive overview on the differences and similarities of photocatalysis and electrocatalysis in the latest 2D nanomaterials.Strategies and traps for performance enhancement of 2D nanocatalysts are highlighted,which point out the differences and similarities of series issues for photocatalysis and electrocatalysis.In addition,2D nanocatalysts and their catalytic applications are discussed.Finally,opportunities,challenges and development directions for 2D nanocatalysts are described.The intention of this review is to inspire and direct interest in this research realm for the creation of future 2D nanomaterials for photocatalysis and electrocatalysis.

Targeted Sub-Attomole Cancer Biomarker Detection Based on Phase Singularity 2D Nanomaterial-Enhanced Plasmonic Biosensor

Detection of small cancer biomarkers with low molecular weight and a low concentration range has always been challenging yet urgent in many clinical applications such as diagnosing early-stage cancer,monitoring treatment and detecting relapse.Here,a highly enhanced plasmonic biosensor that can overcome this challenge is developed using atomically thin two-dimensional phase change nanomaterial.By precisely engineering the configuration with atomically thin materials,the phase singularity has been successfully achieved with a significantly enhanced lateral position shift effect.Based on our knowledge,it is the first experimental demonstration of a lateral position signal change>340μm at a sensing interface from all optical techniques.With this enhanced plasmonic effect,the detection limit has been experimentally demonstrated to be 10^(-15) mol L^(−1) for TNF-α cancer marker,which has been found in various human diseases including inflammatory diseases and different kinds of cancer.The as-reported novel integration of atomically thin Ge_(2)Sb_(2)Te_(5) with plasmonic substrate, which results in a phase singularity and thus a giant lateral position shift, enables the detection of cancer markers with low molecular weight at femtomolar level. These results will definitely hold promising potential in biomedical application and clinical diagnostics.

2D/2D Heterostructures:Rational Design for Advanced Batteries and Electrocatalysis

Two-dimensional/two-dimensional(2D/2D)heterostructures consisting of two or more 2D building blocks possess intriguing electronic features at the nanosized interfacial regions,endowing the possibility for effectively modulating the confinement,and transport of charge carriers,excitons,photons,phonons,etc.to bring about a wide range of extraordinary physical,chemical,thermal,and/or mechanical properties.By rational design and synthesis of 2D/2D heterostructures,electrochemical properties for advanced batteries and electrocatalysis can be well regulated to meet some practical requirements.In this review,a summary on the commonly employed synthetic strategies for 2D/2D heterostructures is first given,followed by a comprehensive review on recent progress for their applications in batteries and various electrocatalysis reactions.Finally,a critical outlook on the current challenges and promising solutions is presented,which is expected to offer some insightful ideas on the design principles of advanced 2D-based nanomaterials to address the current challenges in sustainable energy storages and green fuel generations.

Emerging trends and future challenges of advanced 2D nanomaterials for combating bacterial resistance

The number of multi-drug-resistant bacteria has increased over the last few decades,which has caused a detrimental impact on public health worldwide.In resolving antibiotic resistance development among different bacterial communities,new antimicrobial agents and nanoparticle-based strategies need to be designed foreseeing the slow discovery of new functioning antibiotics.Advanced research studies have revealed the significant disinfection potential of two-dimensional nanomaterials(2D NMs)to be severed as effective antibacterial agents due to their unique physicochemical properties.This review covers the current research progress of 2D NMs-based antibacterial strategies based on an inclusive explanation of 2D NMs’impact as antibacterial agents,including a detailed introduction to each possible well-known antibacterial mechanism.The impact of the physicochemical properties of 2D NMs on their antibacterial activities has been deliberated while explaining the toxic effects of 2D NMs and discussing their biomedical significance,dysbiosis,and cellular nanotoxicity.Adding to the challenges,we also discussed the major issues regarding the current quality and availability of nanotoxicity data.However,smart advancements are required to fabricate biocompatible 2D antibacterial NMs and exploit their potential to combat bacterial resistance clinically.

Niobium oxyphosphate nanosheet assembled two-dimensional anode material for enhanced lithium storage

The development of high-capacity and high-rate anodes has become an attractive endeavor for achieving high energy and power densities in lithium-ion batteries(LIBs).Herein,a new-type anode material of reduced graphene oxide(rGO) supported niobium oxyphosphate(NbOPO_4) nanosheet assembled twodimensional composite material(NbOPO_4/rGO) is firstly fabricated and presented as a promising highperformance LIB anode material.In-depth electrochemical analyses and in/ex situ characterizations reveal that the intercalation-conversion reaction takes place during the first discharge process,followed by the reversible redox process between amorphous NbPO_4 and Nb which contributes to the reversible capacity in the subsequent cycles.Meanwhile,the lithiation-generated Li3 PO_4,behaving as a good lithium ion conductor,facilitates ion transport.The rGO support further regulates the structural and electron/ion transfer properties of NbOPO_4/rGO composite compared to neat NbOPO_4, resulting in greatly enhanced electrochemical performances.As a result,NbOPO_4/rGO as a new-type LIB anode material achieves a high capacity of 502.5 mAh g^(-1) after 800 cycles and outstanding rate capability of 308.4 mAh g^(-1) at 8 A g^(-1).This work paves the way for the deep understanding and exploration of phosphate-ba sed high-efficiency anode materials for LIBs.

Two-dimensional metal oxide nanosheets for rechargeable batteries

Two-dimensional（2D） metal oxide nanosheets have attracted much attention as potential electrode materials for rechargeable batteries in recent years. This is primarily due to their natural abundance, environmental compatibility, and low cost as well as good electrochemical properties. Despite the fact that most metal oxides possess low conductivity, the introduction of some conductive heterogeneous components, such as nano-carbon, carbon nanotubes（CNTs）, and graphene, to form metal oxide-based hybrids,can effectively overcome this drawback. In this mini review, we will summarize the recent advances of three typical 2D metal oxide nanomaterials, namely, binary metal oxides, ternary metal oxides, and hybrid metal oxides, which are used for the electrochemical applications of next-generation rechargeable batteries, mainly for lithium-ion batteries（LIBs） and sodium-ion batteries（SIBs）. Hence, this review intends to functionalize as a good reference for the further research on 2D nanomaterials and the further development of energy-storage devices.

Theoretical Investigation of Structural, Electronic, and Mechanical Properties of Two Dimensional C, Si, Ge, Sn

In this article, we investigate the predictions of the first principles on structural stability, electronic and mechanical properties of 2D nanostructures: graphene, silicene, germanene and stenane. The electronic band structure and density of states in all these 2D materials are found to be generic in nature. A small band gap is generated in all the reported materials other than graphene. The linearity at the Dirac cone changes to quadratic, from graphene to stenane and a perfect semimetalicity is exhibited only by graphene. All other 2D structures tend to become semiconductors with an infinitesimal band gap. Bonding characteristics are revealed by density of states histogram, charge density contour, and Mulliken population analysis. Among all 2D materials graphene exhibits exotic mechanical properties. Analysis by born stability criteria and the calculation of formation enthalpies envisages the structural stability of all the structures in the 2D form. The calculated second order elastic stiffness tensor is used to determine the moduli of elasticity in turn to explore the mechanical properties of all these structures for the prolific use in engineering science. Graphene is found to be the strongest material but brittle in nature. Germanene and stenane exhibit ductile nature and hence could be easily incorporated with the existing technology in the semiconductor industry on substrates.

Recent advances in two-dimensional nanomaterials for bone tissue engineering

Over the last decades,bone tissue engineering has increasingly become a research focus in the field of biomedical engineering,in which biomaterials play an important role because they can provide both biomechanical support and osteogenic microenvironment in the process of bone regeneration.Among these biomaterials,two-dimensional(2D)nanomaterials have recently attracted considerable interest owing to their fantastic physicochemical and biological properties including great biocompatibility,excellent osteogenic capability,large specific surface area,and outstanding drug loading capacity.In this review,we summarize the state-of-the-art advances in 2D nanomaterials for bone tissue engineering.Firstly,we introduce the most explored biomaterials used in bone tissue engineering and their advantages.We then highlight the advances of cutting-edge 2D nanomaterials such as graphene and its derivatives,layered double hydroxides,black phosphorus,transition metal dichalcogenides,montmorillonite,hexagonal boron nitride,graphite phase carbon nitride,and transition metal carbonitrides(MXenes)used in bone tissue engineering.Finally,the current challenges and future prospects of 2D nanomaterials for bone tissue regeneration in process of clinical translation are discussed.

Single-layer graphene as a highly selective barrier for vanadium crossover with high proton selectivity

We report near-zero crossover for vanadium cross-permeation through single-layer graphene immobilized at the interface of two Nafion?polymer electrolyte membranes.Vanadium ion diffusion and migration,including proton mobility through membrane composites,were studied with and without graphene under diffusion and migration conditions.Single-layer graphene was found to effectively inhibit vanadium ion diffusion and migration under specific conditions.The single-layer graphene composites also enabled remarkable ion transmission selectivity improvements over pure Nafion membranes,with proton transport being four orders of magnitude faster than vanadium ion transport.Resistivity values of 0.02±0.005Ωcm^(2) for proton and 223±4Ωcm^(2) for vanadium ion through single atomic layer graphene are reported.This high selectivity may have significant impact on flow battery applications or for other electrochemical devices where proton conductivity is required,and transport of other species is detrimental.Our results emphasize that crossover may be essentially completely eliminated in some cases,enabling for greatly improved operational viability.

Dimensional heterojunction design:The rising star of 2D bismuthbased nanostructured photocatalysts for solar-to-chemical conversion

With the fast-pace digitalization evolution in the current generation’s lifestyle and the industry revolution,the energy demand has been skyrocketed.Recently,the two-dimensional(2D)bismuth-based nanomaterials emerged as a promising photocatalyst candidate in solar fuel conversion,not only for its exceptional light absorption capability and tunable optical properties,but it also can be synthesized into diverse variety of nanomaterials with different ranges of potential gap and band position to fulfill the potential requirement of wide range of photocatalytic reaction.Yet,the weak light harvesting ability and ultrafast charge recombination has restricted its potential in commercial application.Thus,recent researches have been focusing on tackling these issues by incorporating some modification strategies such as heteroatom doping,vacancy engineering,facet engineering,bismuth rich strategy and heterojunction engineering.Herein,this review article presents the state-of-the-art modifications on 2D bismuth-based parent material,specifically on the relationship between each of the modification strategy on the electronic properties and surface chemistry in achieving boosted photocatalytic performance.In the view of the unique charge interaction between two semiconductors with different dimensions,we systematically discuss the rational heterostructure design from the dimensionality perspective,namely,point-to-face,line-to-face,face-to-face,and bulk-to-face in solar fuel conversion to provide inspiring insights for future interface engineering.Finally,the challenges and the future research outlook in the solar-to-fuel conversion are highlighted to push forward the design of high-performance bismuth-based photocatalyst in realizing commercialscale solar-to-fuel conversion.

Two-dimensional Pd-based nanomaterials for bioapplications

Noble metal nanomaterials have been extensively explored in cancer diagnostic and therapeutic applica- tions owing to their unique physical and chemical properties, such as facile synthesis, straightforward surface functionalization, strong photothermal effect, and excellent biocompatibility. Herein, we summa- rize the recent development of two-dimensional （2D） Pd-based nanomaterials and their applications in cancer diagnosis and therapy. Different synthetic strategies for Pd nanosheets and the related nanostruc- tures, including Pd@Au, Pd@Ag nanoplates and mesocrystalline Pd nanocomlla, are first discussed. Together with their unique properties, the potential bioapplications of these 2D Pd nanomaterials are then demonstrated. With strong absorption in near-infrared （NIR） region, these nanomaterials have great potentials in cancer photothermal therapy （PTr）. They also readily act as contrast agents in photoacoustic （PA） imaging or X-ray computed tomography （CT） to achieve image-guided cancer therapy. Moreover, significant efforts have been devoted to studying the combination of PTr and other treatment modalities （e.g., chemotherapy or photodynamic therapy） based on Pd nanomaterials. The remarkable synergistic or collaborative effects to achieve better therapeutic efficacy are discussed as well. Additionally, the biosaf- ety of 2D Pd-based nanomaterials in vitro and in vivo was evaluated. Finally, challenges for the applica- tions of Pd-based nanomaterials in cancer diagnosis and therapy, and future research prospects are highlighted.

Synergetic enhancement of surface reactions and charge separation over holey C_(3)N_(4)/TiO_(2)2D heterojunctions

Efficient charge separation and rapid interfacial reaction kinetics are crucial factors that determine the efficiency of photocatalytic hydrogen evolution.Herein,a fascinating 2D heterojunction photocatalyst with superior photocatalytic hydrogen evolution performance–holey C_(3)N_(4)nanosheets nested with TiO_(2)nanocrystals(denoted as HCN/TiO_(2))–is designed and fabricated via an in situ exfoliation and conversion strategy.The HCN/TiO_(2)is found to exhibit an ultrathin 2D heteroarchitecture with intimate interfacial contact,highly porous structures and ultrasmall TiO_(2)nanocrystals,leading to drastically improved charge carrier separation,maximized active sites and the promotion of mass transport for photocatalysis.Consequently,the HCN/TiO_(2)delivers an impressive hydrogen production rate of 282.3 lmol h^(-1)per10 mg under AM 1.5 illumination and an apparent quantum efficiency of 13.4%at a wavelength of 420 nm due to the synergetic enhancement of surface reactions and charge separation.The present work provides a promising strategy for developing high-performance 2D heterojunctions for clean energy applications.