2D Nanomaterials Research Articles

Tailoring the Properties of 2D Nanomaterial‐Polymer Composites for Electromagnetic Interference Shielding and Energy Storage by 3D Printing—A Review

3D‐printed 2D nanomaterials‐based polymer composites, with their exceptional electrical conductivity and structural functionalities, have become leading‐edge engineering materials for electromagnetic interference (EMI) shielding, sensors, and energy storage applications. This review begins with a brief introduction to various types of 2D nanomaterials and their fabrication techniques, specifically different types of 3D printing. The subsequent sections highlight key factors such as rheological properties, surface tension, additives, and binders that influence the printability of 2D nanomaterials‐based polymer composites. The advancements in 2D nanomaterials‐based polymers, including MXene, graphene, and graphene derivatives, are then presented. The interaction, dispersion, and/or network formation of 2D nanomaterials in the polymer matrix is a crucial factor in determining the electrical performance of the composites. This review also discusses surface modification strategies for 2D nanomaterials to enhance their sensing, EMI shielding, and energy storage capabilities. Finally, the impact of various 3D‐printed polymer composite geometries, such as rectangular, cylinder, and circular, on shielding performance is thoroughly examined, engaging the reader in the exploration of these materials.

Two-Dimensional Rare-Earth Metal Phosphides: From Weyl Semimetal to Semiconductor.

Two-dimensional (2D) nanomaterials have garnered extensive attention owing to their unique properties and versatile application. Here, a family of 2D rare-earth metal phosphides (M2P, M = Sc, Y, La) and their derivatives M2POT (T = F, OH) is developed to find their topological and electronic properties on the basis of density functional theory simulations. We show that the 2D M2P compounds are most possibly obtained from thermodynamically stable M2InP by chemical exfoliation. The In with a substantial atomic radius of 156 pm exhibits weak polarization ability, resulting in homogeneity of the electron cloud and a weakening of the M-In bond relative to the M-P bond. Upon exfoliation of the In layer, the M22+P3-:e- emerges as an electride with surface electrons, which is attributed to the larger ion radius and lower electronegativity of M2+ ions in M2P. The metallic M2P is found to be a Weyl semimetal derived from the contribution of surface electrons. Further, by leveraging the high reactivity of surface electrons, surface functionalization can produce M2POT compounds with the increased valence state of M3+, which results in their semiconducting properties characterized by high carrier mobilities and strong built-in electronic fields. These distinct topological and electronic characteristics position the 2D M2P and M2POT as promising candidates for a wide range of applications.

Maximizing light-to-heat conversion of Ti3C2Tx MXene metamaterials with wrinkled surfaces for artificial actuators

MXene, a promising photothermal nanomaterial, faces challenges due to densely stacked nanosheets with high refractive index (RI). To maximize photothermal performance, MXene metamaterials (m-MXenes) are developed with a superlattice with alternating MXene and organic layers, reducing RI and inducing multiple light reflections. This approach increases light absorption, inducing 90% photothermal conversion efficiency. The m-MXene is coated onto liquid crystal elastomer (LCE) fibers, as actuating platforms via a dip-coating (m-MXene/aLCE fiber), exhibiting excellent light-driven actuating owing to the synergetic effect of the patterned m-MXene laysers by structural deformation. The m-MXene/aLCE fibers lift ~6,900 times their weight and exhibit a work density 6 times higher than that of human skeletal muscle. It is applied to artificial muscles, grippers, and a bistable structure (a shooting device, and switchable gripper). Our study offers an effective strategy to enhance light absorption in 2D nanomaterials and contributes to advancements in photothermal technologies in various fields.

Enhancing Bimetallic SPR Sensor’s Performance: The Role of 2D and TMDC Nanomaterials

Enhancing Bimetallic SPR Sensor’s Performance: The Role of 2D and TMDC Nanomaterials

The beneficial impact of MXene on the electrochemical performance of graphene quantum dots for dopamine detection

Considerable advancements in nanocomposite design have enabled the development of electrochemical sensors with promising features such as remarkable electrocatalytic activities, high electrical conductivity, and effective surface area. For instance, designing nanocomposites using 2D MXenes and 0D nanomaterials can be beneficial to combine the advantages of both individual constituents and enhance the device’s final performance. Herein, we developed a nanocomposite based on Ti3C2 MXene to tailor the electrochemical properties of graphene quantum dots (GQDs) for sensing applications. Specifically, the electrochemical properties of different Ti3C2:GQDs ratios were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimized conditions, the nanocomposite-based sensor showed a linear response to dopamine (DA) in the concentration range of 40 – 400 μM and a limit of detection of 1.8 μM (S/N = 3). Moreover, real sample analysis indicated that spiked DA could be determined accurately by Ti3C2/GQDs/GCE in human urine and sweat samples. The improved sensing performance was attributed to the combined effect of the large surface area of GQDs and the electrical conductivity of MXene, which approach can be extended to develop other electrochemical sensors.

Anti-bacterial efficacy of Boron Nanosheet against clinical isolates and its in vivo toxicity assessment using Artemia salina.

Microbes have been increasing their potential against newly developed drugs and antibiotics daily. The increased microbial drug resistance is still a challenging societal inconvenience. 2D nanomaterials, such as graphene, fascinate researchers with their unique physical and chemical properties and have a major role in current science and technology. Nowadays, researchers have been replacing graphene with its analogous 2D material, borophene, which is a single layer of boron with a honeycomb plane. Boron nanosheets which are theoretically investigated, have been synthesized by various top-down and bottom-up approaches. Our study focuses on synthesizing boron-based material from the precursor MgB2 which possesses a honeycomb boron structure with sandwiched Mg atoms. The Mg atoms have been selectively removed using the chelating agents at alkaline pH. The synthesized boron nanosheets have been characterized by FT-IR, Raman, XRD, FESEM, EDS, and TGA. The formation of B-H-B, B-B and B-O bond is confirmed by FT-IR and Raman spectra. It is also evident from XPS spectra which possess B1s spectra at 193 eV. The efficient chelation and exfoliation is confirmed by EDS and FESEM analysis which shows the presence of Boron and trace amount of Mg with bark like projections. Though there are several studies on antibacterial activity of compounds, generally the studies are with laboratory cultures of bacterial strains. Clinical studies offer more valid results and are very sparse in literature. The use of clinical strains in the present study is one of the novelty. It has also been analyzed for its anti-bacterial activity against clinical strains of B. subtilis, S. aureus, E. coli, and K. pneumonia. Boron nanosheets possess an enhanced zone of inhibition (8mm, 11mm) against clinical strains of B. subtilis where the micro dilution studies show MIC and MBC values as 125μg and 62.5 μg. The in vivo toxicity studies carried out using Brine Shrimp Lethality Assay reveal higher LC50 values of boron nanosheets (>1mg/ml), which in turn portrays its non-toxic nature. Thus, the synthesized boron nanosheets are toxic to multidrug-resistant B.subtilis where it is non-toxic to mammalian cells. Thus, the study could advance the applications of borophene in biomedical applications.

A Critical Appraisal of Functionalized 2-Dimensional Carbon-Based Nanomaterials for Drug Delivery Applications.

The development of an efficient and innovative drug delivery system is essential to improve the pharmacological parameters of the medicinal compound or drug. The technique or manner used to improve the pharmacological parameters plays a crucial role in the delivery system. In the current scenario, various drug delivery systems are available where nanotechnology has firmly established itself in the field of drug delivery. One of the most prevalent elements is carbon with its allotropic modifications such as graphene-based nanomaterials, carbon nanotubes, carbon dots, and carbon fullerenes, these nanomaterials offer notable physiochemical and biochemical properties for the delivery applications due to their smaller size, surface area, and ability to interact with the cells or tissues. The exceptional physicochemical properties of carbon-based 2D nanomaterials, such as graphene and carbon nanotubes, make them attractive candidates for drug delivery systems. These nanomaterials offer a large surface area, high drug loading capacity, and tunable surface chemistry, enabling efficient encapsulation, controlled release, and targeted delivery of therapeutic agents. These properties of the nanomaterials can be exploited for drug delivery applications, like assisting the target delivery of drugs and aiding combination molecular imaging. This review emphasizes on the recent patents on 2D carbon-based nanomaterial and their role in drug delivery systems. Carbon-based 2D nanomaterials present a wealth of opportunities for advanced drug delivery systems. Their exceptional properties and versatility offers great potential in improving therapeutic efficacy, minimizing side effects, and enabling personalized medicine and the recent patents on 2D nanomaterial.

Folded graphene reinforced metal matrix nanocomposites with comprehensively enhanced tensile mechanical properties

It is urgent to develop advanced materials with high strength, high toughness and good ductility for modern engineering structures. Graphene reinforced metal matrix nanocomposites exhibit significantly enhanced strength and toughness, but their ductility remains relatively low due to the inherent tensile brittleness of graphene. Inspired by the origami concept, we utilize the surface hydrogenation method to develop an armchair-like folded graphene (AFG) structure as reinforcement for metal matrix composites. Molecular dynamics simulations show that the AFG structure can simultaneously enhance the tensile strength, stiffness, ductility, and toughness of copper (Cu) matrix composites. Compared with pristine graphene/Cu nanocomposites, AFG/Cu nanocomposites exhibit better ductility and toughness, while maintaining comparable strength and stiffness. Furthermore, the mechanical properties of AFG/Cu nanocomposites can be tuned by altering the degree of AFG folding and the distances between adjacent hydrogenated zones. The strengthening and toughening mechanism is that mechanically strong AFG can effectively block dislocation propagation across the metal-graphene interface before it unfolds to fracture. Such mechanism can be extended to other 2D nanomaterials reinforced metal matrix nanocomposites, opening up an avenue for developing high-performance nanocomposites.

End-to-End Pierced Carbon Nanosheets with Meso-Holes.

The remarkable properties of 2D nanomaterials are well known. However, their high interfacial adhesion energy often leads to restacking issues, limiting their potential in various applications. A strategic synthetic approach is presented to overcome this challenge. Specifically, the study first demonstrates the use of layered aluminosilicate as a sacrificial 2D template to allow the growth of highly ordered meso-holey polymeric layers, which can be subsequently exfoliated upon the removal of aluminosilicate and thermally converted to perpendicularly open meso-holey carbon (POMC). On the other hand, perpendicularly blocked meso-holey carbon (PBMC) is obtained with non-sacrificial 2D template of graphene oxide. When both POMC and PBMC are evaluated by operando hydrodynamic electrochemical impedance spectroscopy and transmission line model analysis for electrochemical reduction of oxygen, POMC achieves a remarkable improvement of charge transfer and mass transfer by up to 4.1 and 7.9 times, respectively, as compared to PBMC. This study therefore highlights the importance of perpendicularly open 2D nanoarchitectures in circumventing the restacking effect, offering valuable insights for leveraging 2D nanomaterials with open meso-holes in various applications.

Monolayer and bilayer BP as efficient optoelectronic materials in visible and ultraviolet regions

Hexagonal boron phosphide (BP) shows significant promise for optoelectronic applications due to its high carrier mobility and moderate band gap. Strain inevitably occurs during the synthesis of two-dimensional (2D) nanomaterials. In this work, a detailed study on the strain-dependent phonon dispersion and optical properties of monolayer and bilayer BP was performed. The calculated phonon dispersion curves demonstrate that both monolayer and bilayer BP systems remain dynamically stable under tensile strain. By increasing tensile strain, the LO and TO modes soften and the phonon band gap between optical and acoustic modes becomes narrower. The LO and TO modes display expanded phonon spectra under large tensile strains in contrast to the ZA mode. The absorption edge of bilayer BP is located around 0.6 eV, lower in energy with respect to the monolayer BP at ∼ 0.8 eV. The results indicate that the optical absorption may be enhanced by applying the compressive strain. With their broad absorption range and strain-tunable absorption strength and phononic properties, monolayer and bilayer BP are highly promising for next-generation nanodevices.

A bifunctional self-healing coating enhanced by attapulgite functionalized MXene with inhibitor integration

Ti3C2Tx nanosheets, emerging as revolutionary 2D nanomaterials, have sparked interest in advanced applications due to their thin-layered architecture and promise as innovative nanofillers for a variety of applications. To address the oxidation and stacking of Ti3C2Tx nanosheets with the polymer, a novel multifunctional Ti3C2Tx-based nanocomposite is engineered by an etching method. The Ti3C2Tx surface is functionalized with 3-aminopropyltriethoxysilane (APTES), and attapulgite (ATP) is implanted on the NH2-Ti3C2Tx interface to lower the cohesive energy between nanosheets. The novel self-healing epoxy films were achieved by encapsulating self-healing components ((8-hydroxyquinoline (8-HQ) + 2-mercaptobenzothiazole (MBT)) in the ATP-based NH2-Ti3C2Tx nanocomposite (AMQM). Inhibited AA2024-T3 surface revealed hydrophobic nature, whereas the pH sensitive coatings exhibited strong adherence to the substrate and improved compatibility and mechanical strength. The impedance of artificially scratched epoxy film rose from 0.073 M Ω cm2 to 0.198 M Ω cm2 (after 12 h) and from 0.027 M Ω cm2 to 2.189 M Ω cm2 (after 96 h) in comparison with the control samples. Simulations depict the presence of hydrogen bonds between the inhibitors and the 2024-T3 alloy, as well as twice the adsorption energy compared to the individual inhibitors. Therefore, a novel pH-sensitive self-healing coating offers a synergistic approach for promising corrosion suppression.

Wedge-Like Microstructure of Al2O3/i-Ti3C2Tx Electrode with "Nano-Pumping" Effect for Boosting Ion Diffusion and Electrochemical Defluoridation.

Controlled synthesis and regulation of 2D nanomaterials with sufficient active sites are promising in electrochemical fluorine capture, but simultaneously achieving rapid rates and efficient activity of intercalation materials remains challengs. Herein, an integrated strategy of micro-regulation interlayer space and in situ modification of MXenes is proposed to enhance ion storage kinetics. The wedge-like microstructure of aluminum oxide/incomplete-Ti3C2Tx MXene (Al2O3/i-Ti3C2 Tx) is constructed by incomplete etching MAX and in situ derivation of A-layer element, in which the sub-nanoscale interlayer space is conducive to the small size ions intercalation, and the formation of "nanopump-like" effect boosted the ions diffusion. As evidenced by simulation calculations, Al2O3 nanoparticles not only shorten the migration distance of electrons/hydrated ions in interlayers but also contribute a lower adsorption energy barrier, bringing excellent capture kinetics and stability. Benefiting from the interfacial conversion-intercalation pseudocapacitance, such electrode is endowed with a high defluoridation capacity (69.9 mg g-1 at 1.6V) and an outstanding instantaneous adsorption rate (9.51 mg g-1 min-1), and shows satisfactory stability in more than 200 cycles. The physicochemical coupling strategy opens a novel approach to optimizing the interlayer structure and in situ modification interface of MXene, which also provids a universal idea for efficient capture of varisized ions of intercalation materials.

The Design of WTe2/Graphene/Ag NPs Heterostructure for the Improvement of the Chemical Enhancement in SERS.

Combining the advantages of metal and two-dimensional (2D) nanomaterials, various 2D/metal composite structures are proposed as surface-enhanced Raman spectroscopy (SERS) substrates. However, the chemical enhancement in the composite structure is usually less responsible for the total enhancement. In this work, we proposed a heterostructure including WTe2/graphene/Ag nanoparticles (WTe2/Gr/Ag) as an effective platform for SERS. The matching of energy levels facilitates charge transfer (CT) within the composite structure, which in turn significantly improves the chemical enhancement of SERS. Compared with WTe2/Ag or Gr/Ag substrate, the SERS signals can be amplified up to 18-fold, and the detection limit could further reduce 3 orders of magnitude. Furthermore, the CT process in the SERS test can be further promoted after introducing the pyroelectric field based on the ferro-electricity of WTe2. The enhancement factor of the WTe2/Gr/Ag substrate finally reached 1.34 × 1012. This work proposes a new idea for the design of highly sensitive SERS sensors.

The Impact of Pore Geometry on Frictional Properties of hBN and MoS2 Nanomaterials.

Two-dimensional (2D) nanomaterials hold significant promise for reducing energy consumption in water desalination. This study investigates the influence of pore size and shape on the slip behavior of saline water at the interface of two promising 2D nanomaterials: hexagonal boron nitride (hBN) and molybdenum disulfide (MoS2). Slip length, a key parameter governing fluid flow at the nanoscale, is highly dependent on interfacial properties. Here, we explore how the pore characteristics in these 2D nanomaterials can impact slip length, aiming to gain a fundamental understanding of the role of pore size and shape in optimizing desalination efficiency. We performed quantum mechanical calculations to compute the partial atomic charges on atoms in hBN and MoS2 containing pores. Our DFT calculations reveal a spatially varying charge distribution on these 2D nanomaterials with pores, which we then incorporate into molecular dynamic simulations to elucidate their influence on the 2D nanomaterial-water interface. Our results reveal a significant impact of pore size on friction for nanomaterials containing hexagonal pores, while pore size had no effect on nanomaterials containing triangular pores. Moreover, friction increases with pores in both materials. This research contributes to the development of efficient and energy-saving desalination technologies through the manipulation of interfacial properties in 2D nanomaterials.

MXene Electrocatalysts: Transformative Approaches in Hydrogen Production with Alternative Anode Reactions.

Water electrolyzer is crucial for producing clean hydrogen, but the traditional approach faces challenges owing to the oxygen evolution reaction (OER) slow kinetics at the anode. Hybrid water splitting replaces the OER with the oxidation of an organic molecule to enhance hydrogen production along with value-added products. The scarcity of affordable and highly effective catalysts remains a major challenge. MXene, a 2D nanomaterial, has gained substantial attention for its enviable properties, for instance high conductivity, hydrophilicity, and substantial surface area. This review discusses experimental methods for synthesizing MXene and MXene-based nanocomposites. Furthermore, the small molecules oxidation such as benzyl alcohol, methanol, ethanol, urea, hydrazine, furfural, and formic acid as alternatives to the oxygen evolution reaction is examined. Finally, an understanding of imminent research and the development of MXene-associated materials in electrocatalytic applications are presented.

Advanced 2D Nanomaterials for Phototheranostics of Breast Cancer: A Paradigm Shift.

Breast cancer is the leading cause of women's deaths and associated comorbidities. The advanced and targeted strategies against breast cancer have gained considerable attention due to their potential enhanced therapeutic efficacy over conventional therapies. In this context, phototherapies like photodynamic therapy (PDT) and photothermal therapy (PTT) have shown promise as an effective and alternative strategy due to reduced side effects, noninvasiveness, and spatiotemporal specificity. With the advent of nanotechnology, several types of nanomaterials that have shown excellent prospects in increasing the efficacy of photo therapies have been exploited in cancer treatment. In recent years, 2D nanomaterials have stood out promising because of their unique ultrathin planar structure, chemical, physical, tunable characteristics, and corresponding remarkable physiochemical/biological properties. In this review, the potential and the current status of several types of 2D nanomaterials such as graphene-based nanomaterials, Mxenes, Black phosphorous, and Transition Metal Dichalcogenides for photo/thermo and combination-based imaging and therapy of breast cancer have been discussed. The current challenges and prospects in terms of translational potential in future clinical oncology are highlighted.

2D Nano-Photosensitizer Facilitates Proximity Labeling for Living Cells Surfaceome Deciphering.

Photocatalytic proximity labeling has shown great promise for mapping the spatiotemporal dynamics of surfaceome. Although cell-surface targeting photosensitizers relying on antibodies, lipid molecules, and metabolic labeling have gained effects, the development of simpler and stable methods that avoid complex chemical synthesis and biosynthesis steps is still a huge challenge. Here, the study has introduced 2D nanomaterials with the ability of cell surface engineering to perform the in situ anchoring of photosensitizer on living cell surface. Photosensitizer can be stabilized on nanomaterials by coordination after one-step mixing, resulting in the nano-photosensitizer combining cell surface targeting ability and photosensitivity that allowing surface-specific proximity labeling. Nano-photosensitizer can be dispersed stably in aqueous solution, avoiding the defects of poor water solubility and aggregation of traditional organic photosensitizers. Singlet oxygen is generated locally under light irradiation, enabling spatiotemporally-resolved activating and labeling of cell surface proteome. Further application in the brain metastatic lung cancer has been found effective with numerous quantified differential cell surfaces proteins highly correlated with cancer metastasis and three potential players have been validated via immunoblotting and immunofluorescence, providing important insights for metastasis supported molecular mechanism.

Study of Azobenzene-modified Black Phosphorus for Potential Tumor Therapy.

Exploring the interaction between black phosphorus (BP)-based hybrid systems and target proteins is of great significance for understanding the biological effects of 2D nanomaterials at the molecular level. Density functional theory (DFT) calculations revealed that different terminal groups of the azobenzene (AB) motif in BP@AB hybrids can affect the extent of interfacial charge transfer between the BP sheet and AB-derivatives, which determines the electrostatic interaction with proteins and hence biofunctions of BP@AB hybrids. With the advantage of AB modification, BP@AB hybrids displayed antitumor effects and induced production of cellular reactive oxygen species and apoptosis in cancer cells. Through the proteomics profiling, cellular ribosome and lipid metabolic processes were screened out as the target pathways of the BP@AB-NH2 in HeLa cells, while the BP@AB-S-S-AB system mainly targets the ERBB and PPAR signaling pathways. Molecular docking simulations revealed that due to the positive charge, ribosomal pathway proteins enriched in negatively charged amino acids such as lysine and arginine are preferentially adsorbed and bound by BP@AB-NH2 hybrids. Whereas for BP@AB-S-S-AB, receptors containing narrow and long pocket domains are more likely to bind with BP@AB-S-S-AB by van der Waals forces for the rod-like hybrids. Different biomolecule targeting and action modes of BP@AB hybrids have been rationalized by different electrostatic environments and matching of geometric configurations, shedding insight for designing efficient and targeted modification of a 2D nanomaterial-based strategy for cancer therapy.

Improved tribological properties of MXene nanosheet filler-modified PPO composites

MXenes, a class of two-dimensional (2D) nanomaterials, exhibit exceptional properties such as outstanding mechanical and thermal stability, along with diverse surface characteristics, making them highly promising in the tribology. However, their tendency to aggregate within the polymeric matrix adversely affects the tribological performance of the polymer. In this study, glass fiber (GF) surfaces were modified with polydopamine (PDA), allowing smaller MXene nanosheets to adhere to the GF surface, whereas the larger MXene nanosheets were dispersed throughout the matrix. This approach effectively enhanced the dispersion of MXene nanosheets in the polymeric matrix, facilitating the preparation of polyphenylene oxide (PPO)/MXene composite materials. Compared with the pure PPO sample, the results showed that the average friction coefficient and wear rate of the PPO/MXene composites were reduced by 46.25% and 98.34%, respectively, due to the distinct roles of different MXene nanosheet sizes in the polymeric matrix. Furthermore, a uniform lubricating film was formed during the friction of the polymer composite, enhancing its tribological performance. This study proposes a novel design strategy to enhance MXene nanosheet dispersion and optimize their lubricating properties.

Vacancies Engineering in Molybdenum Boride MBene Nanosheets to Activate Room-Temperature Ferromagnetism.

The rapid development of low energy dissipation spintronic devices has stimulated the search for air-stable 2D nanomaterials possessing room-temperature ferromagnetism. Here the experimental realization of 2D Mo4/3B2 nanosheets is reported with intrinsic room-temperature ferromagnetic characteristics by vacancy engineering. These nanosheets are synthesized by etching the bulk MAB phase (Mo2/3Y1/3)2AlB2 into Mo4/3B2 nanosheets in ZnCl2 molten salt. The Mo4/3B2 nanosheets show robust intrinsic ferromagnetic properties, with a saturation magnetic moment of 0.044emug-1 at 300K, while vacancy-free MoB MBene exhibits paramagnetism. It is elucidated that the Mo-vacancy defect generates large density of states near the Fermi surface and spontaneously spin-split bands through first-principles calculations, which contributes to the non-zero magnetic moment in Mo4/3B2 nanosheets. This work lays the groundwork for activating the magnetic properties of MBene nanosheets by vacancy engineering, offering the possibilities for development of practical spintronic devices.