Two-dimensional MXene Research Articles

Polydopamine-modified MXene-integrated photothermal responsive hydrogel for constructing rapid photothermal and self-sensing gradi- ent hydrogel actuators

Abstract PNIPAm-based stimuli-responsive hydrogel actuators have made significant progress. By introducing responsive modules such as photothermal nanoparticles, the hydrogel can respond to environmental changes and construct anisotropic structures, allowing the hydrogel actuators to quickly bend and realize complex shape deformation. How-ever, there remains a need to enhance the mechanical properties of these hydrogels to accommodate multiple deformation actions and different application scenarios, and enhance the compatibility between nanoparticles and the hydrogels to improve the comprehensive performance of materials are still issues that need to be solved. In this study, we modified two-dimensional MXene nanosheets with polydopamine (PDA) to obtain P-MXene, which served as a photothermal agent and can be stably dispersed within the hydrogel system. We copolymerized thermosensitive N-isopropylacrylamide (NIPAm) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) in situ and used a direct current (DC) electric field to induce a concentration gradient distribution of P-MXene nanosheets within the hydrogel, resulting in the preparation of anisotropic gradient hydrogel actuators with good stretchability and conductivity. The hydrogel structure was characterized using scanning electron microscopy (SEM) and the Fourier transform infrared (FTIR) spectra. The swelling properties, mechani-cal properties and conductivity of the hydrogel were studied. The actuation behavior of P(NIPAm-DMAEMA)/P-MXene gradient hydrogel actuators under different thickness and electric field intensity was investigated. Additionally, the sensitivity and stability of the conductive hydrogel actuators were tested. and the functions of monitoring human health and information transmission were realized. It integrated with rapid photo responsiveness and self-sensing capabilities to monitor the defor-mation process of the actuators through real-time relative resistance changes during the actuations. This work is expected to expand the application field of soft hydrogel actuators and provide new insights into the design of a new generation of soft robots.

Impact of PEDOT:PSS/Ti3C2Tx composite hole transport layer on the performance of perovskite light emitting diodes

The two-dimensional transition metal carbide MXenes, often designated by Ti3C2Tx, have garnered significant interest on account of their distinctive optoelectronic characteristics. In this paper, PEDOT:PSS/Ti3C2Tx composite hole transport layer (HTLs) was prepared by adding the MXenes material Ti3C2Tx into PEDOT:PSS, and quasi-two-dimensional perovskite light-emitting diodes (PeLEDs) were fabricated and investigated. While the addition concentration of Ti3C2Tx was 0.25 mg/mL, the optimal device shows the maximum luminance of 6250 cd/m2, and the current efficiency of 6.17 cd/A, which is 133 % and 112 % higher than the reference device without Ti3C2Tx, respectively. It is indicated that the additive incorporation of Ti3C2Tx in PEDOT:PSS can improve the efficiency of hole injection and conductivity of hole transport layer, and passivate the defects of perovskite film, thus enhancing the optoelectronic performance of PeLEDs. The findings of this study indicate that the PEDOT:PSS/Ti3C2Tx composite HTLs has considerable potential for application in PeLEDs.

An Efficient Cathode Catalyst for Rechargeable Zinc-air Batteries based on the Derivatives of MXene@ZIFs.

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial processes at the cathode of zinc-air batteries. Developing highly efficient and durable electrocatalysts at the air cathode is significant for the practical application of rechargeable zinc-air batteries. Herein, N-doped layered MX containing Co2P/Ni2P nanoparticles is synthesized by growing CoNi-ZIF on the surface and interlayers of the two-dimensional material MXene (Ti2C3) followed by phosphating calcination. The growth of CoNi-ZIF on the surface of MXene results in the attenuation of high-temperature structural damage of MXene, which in turn leads to the formation of Co2P/Ni2P@MX with a hierarchical configuration, higher electron conductivity, and abundant active sites. The optimized Co2P/Ni2P@MX achieves a half-wave potential of 0.85 V for the ORR and an overpotential of 345 mV for the OER. In addition, DFT calculations were adopted to investigate the mechanism at the atomic and molecular levels. The liquid zinc-air battery with Co2P/Ni2P@MX as the cathode exhibits a specific capacity of 783.7 mAh g-1 and exceeds 280 h (840 cycles) cycle stability, superior to zinc-air batteries constructed by the cathode of commercial Pt/C+RuO2 and other previous works. Furthermore, a solid-state battery synthesized with Co2P/Ni2P@MX as the cathode exhibits stable cycle performance (154 h/462 cycles).

Hexafluoroisopropanol modified MXene for perovskite surface remodeling and interfacial dipole effect enhancement

The development of high-efficiency and stable perovskite (PVK) solar cells (PSCs) still faces the challenge of non-ideal interfaces between PVK and charge transport layers. Herein, the hexafluoroisopropanol (HFIP) modified two-dimensional Ti3C2Tx MXene is custom-made (MX-HFIP) and employed as the interlayer between the PVK and hole transport layer (HTL) interface by forming hydrogen bonds. The MX-HFIP serves to reinforce the interface contact and remodel the surface of PVK, leading to a high-quality PVK film with a significantly reduced defect density, suppressed nonradiative recombination, and inhibited invasion of water and oxygen. Moreover, the synergistic effect of MXene and HFIP results in an enhanced interfacial dipole effect and an optimized energy-level alignment, thereby increasing the driving force for charge extraction and transport at the PVK/HTL interface. Therefore, the MX-HFIP treated PSC achieves a substantially-enhanced power conversion efficiency (PCE) of 22.33 %, as compared to 20.05 % of the untreated device. Besides, the MX-HFIP treated PSC delivers significantly enhanced stabilities, with 88 % of its initial PCE after 1656 h of storage at 25 °C under 30 %⁓40 % relative humidity. These findings demonstrate the advancement using fluorine-rich molecule modified MXene to improve interfacial properties for enhancing performances and stabilities of optoelectronic devices.

Utilizing electrooxidation for textile effluent wastewater treatment and simultaneous electrocatalytic hydrogen production: Transforming waste into energy and promoting water reuse in a circular economy context

Textile effluent wastewater poses a serious environmental risk because of its high concentration of pollutants, which include organic compounds, heavy metals, and dyes. The present study investigates the technical and economic feasibility of hybrid water electrolysis performances. Specifically, real textile effluent wastewater was utilised to examine simultaneous abatement and electrochemical hydrogen production. The treated water can be recycled in the textile mill, offering the benefits of trash-to-treasure and cost savings through the circular economy. In addition to reducing the environmental impact of textile wastewater, the synergistic approach seeks to maximise its potential for producing hydrogen as clean energy. Here, the commercially available stainless sheet was used as the anode in the electrochemical setup system and the two-dimensional Ti3C2TX MXene was used as the catalyst embedded cathode. The optimal electrode-electrolyte parameter settings resulted in an 83 % decrease in COD level and a degradation efficiency of about 88 %. The potential for widespread adoption in the textile industry is highlighted by the discussion of the economic viability and environmental advantages of using wastewater from textile effluents for pollutant degradation and hydrogen production. Hence, the energy estimation was looked at and estimated in order to evaluate the process viability. For instance, the hybrid electrolysis process uses a very small amount of electricity (0.825 kWh m−3 order−1) and has an apparent operating current (30 mA/cm2). This work could serve as a guide for the methodical assessment and choice of hybrid water electrolysis using actual wastewater. The electrode's recyclability and reuse were proven for possible commercial applications. The stability of the Ti3C2TX electrode over a wide pH range was investigated in order to produce hydrogen on a big scale at a reasonable cost.

Ternary MXene/PANI/ZnO-based composite with a built-in p–n heterojunction for high-performance supercapacitor applications

Abstract Two-dimensional (2D) Ti3C2T x MXene-based materials have attracted widespread attraction in the field of energy storage owing to their high conductivity and accordion-like structure. However, challenges such as restacking and oxidative degradation of the Ti3C2T x MXene structure lead to poor stability, low conductivity, low specific capacitance and, consequently, a low specific energy, hindering their extensive adoption at an industrial scale. In this study, a ternary MXene/polyaniline (PANI)/ZnO (MPZ) composite has been synthesized via surface engineering of two-dimensional (2D) MXene using one-dimensional (1D) PANI nanowires and ZnO nanoparticles to enhance its specific energy and stability while sustaining its specific power. 1D PANI nanowires and ZnO nanoparticles act as spacers to prevent restacking, while also exposing the suppressed redox active sites of 2D MXene and preventing it from being oxidized by forming a porous conductive network all over the surface of the MXene. PANI and ZnO also provide additional electroactive redox sites by forming p–n heterojunctions, thus enhancing faradaic redox reactions and the specific capacitance of the MPZ composite. As a result, the overall electrochemical performance and stability of the ternary MPZ composite are enhanced due to the synergistic interactions among the individual components within the ternary MPZ composite. At a low current density of 0.1 A g−1, the ternary MPZ composite exhibited a maximum specific capacitance of 651.96 F g−1 and a highest specific energy of 32.59 Wh Kg−1 while maintaining a specific power of 60 W Kg−1 as compared to MXene and binary MP composite. Furthermore, it showcased exceptional cyclic stability over 10 000 cycles with 94.75% and 92.95% capacitive retention at 0.6 A g−1 current density and 40 mV s−1 scan rate, respectively. Thus, this current study highlights an effective strategy to enhance the specific energy of MXene-based supercapacitors through surface engineering and the construction of p–n heterojunctions within the composite.

A novel four-modal nano-sensor based on two-dimensional Mxenes and fully connected artificial neural networks for the highly sensitive and rapid detection of ochratoxin A

Timely and accurate on-site detection of ochratoxin A (OTA) is extremely important for global public health. In this study, a fluorescence/colorimetric biosensor based on Ti3C2 nano-materials (Ti3C2-NMS) and a machine-learning (ML) based fluorescence/colorimetric intelligent learning system for detection of OTA concentration (COTA) were developed. The sensor was fabricated by functionalizing Ti3C2-NMS prepared by physical-exfoliation assisted metal-ion-induction using ssDNA. The Ti3C2-NMS exhibited good fluorescence quenching characteristics (FQC) and peroxidase-like activity (PLA). More surprisingly, the functionalization of Ti3C2-NMS by ssDNA further enhanced the FQC and PLA of the material, which could be used for dual-mode detection of OTA. When different COTA existed, ssDNA competitively bound to OTA, resulting in regular changes in fluorescence and colorimetric signals of the sensor, which realized the accurate and sensitive biosensing detection of OTA in two modalities. Based on a series of fluorescent/colorimetric RGB datasets collected by a self-developed application, a dual-channel ML model had been developed. This model can be integrated into mobile phones, clouds, and PCs to achieve intelligent sensing detection of OTA with the assistance of fully connected artificial neural networks. The method constructed had high specificity, low cost, and fast responsiveness, with a LOD as low as 1.58 pg mL−1, indicating excellent potential for application and promotion.

Stretchable, self-adhesive, and conductive hemicellulose-based hydrogels as wearable strain sensors

Conductive hydrogels have recently gained impressive attention in flexible sensing. However, their low sensing limit and poor interface matching have raised great concern during the practical application. Therefore, incorporating excellent stretchability and adhesiveness into conductive hydrogel is highly desirable but still be a huge challenge. In this study, we synthesized composite hydrogels with desired properties by utilizing the synergistic role of hemicellulose (HC) and conductive two-dimensional material MXene. As a result, the synthesized hydrogels showed good self-adhesion (3.12 KPa on the skin), great stretchability (>1700 %), and satisfactory electrical conductivity. These multifunctional hydrogels operated as adaptable sensors, adeptly capturing the nuanced signals emanating from an array of human motions. They exhibited an expansive strain tolerance, swift reactivity, and an enhanced acuity in detecting even the slightest deformations (GF = 2.1). Our research provides new insights for creating stretchable, self-adhesive, and functional hydrogels for sensing applications.

Novel multi-layered MXene as laser desorption ionization mass spectrometry matrix for rapid detection of small biomolecules

Five two-dimensional multi-layered MXenes namely MO2C, Ti2C, V2C, Nb2C and Ta2C were synthesized by a one-step exfoliation process and evaluated as laser desorption ionization mass spectrometry (LDI-MS) matrices for fast detection of small biomolecules for the first time. Among them, Nb2C exhibited the best performance due to its high carrier mobility, strong photo-induced charge transfer resonance and good UV absorption ability. A simple, universal and efficient LDI-MS platform was established for small biomolecule analysis based on the Nb2C matrix. Key factors that affect LDI-MS efficacy were investigated and the established method demonstrated ultraclean MS background, high sensitivity with detection limits low to fmol level and good reproducibility. The Nb2C-based LDI-MS platform was successfully applied in the rapid determination of 13 amino acids (AAs) in human serum and 3 AAs, as potential biomarkers, were found to be significantly down-regulated in major depressive disorder patients. This work proved the feasibility of Nb2C MXene as an LDI-MS matrix and provided a promising and universal platform for the rapid detection of small molecules in biomedical research.

2D MXene nanosheet dispersed Mn, Ru NPs loaded Ti composite electrodes for electrocatalytic synergistic degradation of antibiotics in high-salt mariculture wastewater

In this study, a composite electrode based on etched TiO2 nanotube arrays and two-dimensional (2D) MXene nanosheets was successfully designed for efficient degradation of antibiotics in mariculture wastewater. The composite electrode effectively dispersed Mn and Ru nanoparticles (NPs) by introducing 2D MXene nanosheets as an intermediate layer, which significantly enhanced the catalytic performance. The bifunctional properties of Mn and Ru NPs in catalysis and the contribution of d-orbital electrons to the formation of metal‑hydrogen bonds were revealed in depth by analyzing the electron transfer mechanism at the electrodes. The experimental results demonstrated a synergistic catalytic effect between Mn and Ru bimetals and MXene, resulting in an effective increase in the degradation rate. Under the optimal conditions, the degradation rate of Tetracycline (TC) by Mn/Ru/MXene/Ti composite electrode could reach 90.69 % in 60 min. In addition, it still shows excellent stability after 45 days of air exposure, 10 cycling experiments, and 10,000 s of timed current testing. Mechanistic studies have demonstrated that anode hydroxyl radical (·OH), HClO, and cathode activated hydrogen atoms (H*) all play catalytic roles in the degradation process. The degradation pathways were analyzed using density-functional theory (DFT) calculations and liquid-liquid-mass spectrometry (LC-MS) techniques, with further experiments confirming that this degradation process effectively reduces the biotoxicity of intermediate products, improving the safety of wastewater discharge. Finally, we designed the reactor and calculated the energy consumption to verify the feasibility and economy of the system in practical applications. This research proposes a novel multi-metal co-catalysis and cathode and anode co-catalysis system for the efficient degradation of antibiotics in mariculture wastewater, with potential applications in the electrocatalytic degradation of antibiotics.

Catalytic chitosan/MXene/GO nanocomposite membrane for removing dye and heavy metals

This work reported the preparation of a catalytic nanocomposite nanofiltration (NF) membrane and its performance in removing dye and heavy metals without requiring UV irradiation. Two-dimensional (2D) materials MXene and graphene oxide (GO) were employed in developing chitosan-based catalytic nanocomposite membranes for the removal of dye molecules and heavy metals from textile industry wastewater. The incorporated MXene catalytically decomposed the hydrogen peroxide (H2O2) and generating reactive oxygen species (ROS), which oxidize methylene blue (MB) and reduce cobalt (Co2+) and copper (Cu2+) ions. The electron paramagnetic resonance spectroscopy and fluorescence emission spectroscopy confirmed the generation of superoxide radicals (•O2−). The fabricated chitosan/MXene/GO (CMG) membrane in this research exhibited high removal efficiencies of 96 %, 78 % and 76 % for dye, cobalt ions and copper ions, which were 4, 3.9 and 4 times higher than that of neat membrane, respectively. Similar results of 95 % were also observed in total organic matter (TOC) removal for both concentrations of dye. The CMG membrane also showed superior organic fouling resistance. The findings provided a new insight for non-UV dependent catalytic nanocomposite NF to efficiently remove hazardous contaminants such as dye and heavy metals from industrial effluent.

Double network hydrogel confined MXene/Liquid metal by dynamic hydrogen bond for high-performance wearable sensors

Double-network (DN) hydrogels, which integrate long-chain and short-chain molecular structures, exhibit significant potential in wearable sensors due to their exemplary mechanical properties. However, conventional hydrogels often suffer from poor conductivity and low sensitivity. In this study, we develop a novel DN hydrogel (comprising polyacrylamide/sodium alginate) that encapsulates MXene (Ti3C2Tx) and liquid metal (LM). This configuration leverages the conductive properties of two-dimensional MXene and zero-dimensional liquid metal embedded within the DN hydrogel networks. The Ti3C2Tx MXene sheets enhance the binding capacity with LM by serving as a conductive bridge, thereby improving interfacial interactions and reducing hysteresis. The resultant strain sensor, fabricated from this composite DN hydrogel, achieves high sensitivity (gauge factor up to 12.84), a broad detection range (0 %-1500 %), rapid response time (262 ms), and excellent repeatability and stability. We have integrated this strain sensor into wearable flexible devices, such as contact lenses, enabling real-time monitoring of human physiological pressures.

Two-Dimensional MXene Flakes with Large Second Harmonic Generation and Unique Surface Responses.

MXenes are a family of two-dimensional (2D) materials with broad and varied applications in biology, materials science, photonics, and environmental remediation owing to their layered structure and high surface area-to-volume ratio. MXenes have exhibited significant nonlinear optical characteristics, which have been primarily explored in the context of photonics applications, yet the second-harmonic generation (SHG) behavior of MXenes remains an unexplored aspect of their optical properties. Herein, we demonstrate and quantify large second-order responses of 2D Ti3C2Tx MXenes both in aqueous solutions and on a silicon substrate for the first time. MXene flakes showed strong second-harmonic scattering (SHS) in a dilute suspension with a sensitivity of less than 0.1 μg/mL. Angle-dependent SHS experiments further found that the second-order responses originate from coherent 2D dipole radiation. Through confocal and atomic force microscopies, we found that the intense SHG signal from free-standing MXene flakes increases exponentially with decreasing thickness, while two-photon fluorescence increases linearly with thickness. The second-order susceptibility of the MXenes was determined to be 3.6 pm V-1 with a thickness of 10 nm, almost twice of that for an often-used SHG crystal, beta barium borate. We further explored surface properties of the MXene sheets by investigating the SHS responses upon addition of organic dye molecules to the system. It was found that the adsorption of crystal violet (CV) obeys a Langmuir adsorption model while the addition of malachite green (MG) resulted in almost no change in SHG intensity, even though the adsorption capacities for both CV (61.3 ± 1.7 mg/g) and MG (54.8 ± 2.8 mg/g) are similar. Such a stark difference in adsorption characteristics between cationic organic CV and MG dyes is likely due to their distinct orientational orderings on the MXene surfaces. This work opens many possibilities for the further employment of the family of 2D materials in photonics, optics, and surface catalysis applications.

Coral-like Ti3C2Tx/PANI Binary Nanocomposite Wearable Enzyme Electrochemical Biosensor for Continuous Monitoring of Human Sweat Glucose

With the continuous advancement of contemporary medical technology, an increasing number of individuals are inclined towards self-monitoring their physiological health information, specifically focusing on monitoring blood glucose levels. However, as an emerging flexible sensing technique, continuous and non-invasive monitoring of glucose in sweat offers a promising alternative to conventional invasive blood tests for measuring blood glucose levels, reducing the risk of infection associated with blood testing. In this study, we fabricated a flexible and wearable electrochemical enzyme sensor based on a two-dimensional Ti3C2Tx MXene nanosheets and coral-like polyaniline (PANI) binary nanocomposite (denoted as Ti3C2Tx/PANI) for continuous, non-invasive, real-time monitoring of sweat glucose. The exceptional conductivity of Ti3C2Tx MXene nanosheets, in conjunction with the mutual doping effect facilitated by coral-like PANI, significantly enhances electrical conductivity and specific surface areas of Ti3C2Tx/PANI. Consequently, the fabricated sensor exhibits remarkable sensitivity (25.16 μA·mM−1·cm−2), a low detection limit of glucose (26 μM), and an extensive detection range (0.05 mM ~ 1.0 mM) in sweat. Due to the dense coral-like structure of Ti3C2Tx/PANI binary nanocomposite, a larger effective area is obtained to offer more active sites for enzyme immobilization and enhancing enzymatic catalytic activity. Moreover, the sensor demonstrates exceptional mechanical performance, enabling a 60° bend in practical applications, thus satisfying the rigorous demands of human sweat detection applications. The results obtained from continuous 60 min in vitro monitoring of sweat glucose levels demonstrate a robust correlation with the data of blood glucose levels collected by a commercial glucose meter. Furthermore, the fabricated Ti3C2Tx/PANI/GOx sensor demonstrated agreement with HPLC findings regarding the actual concentration of added glucose. This study presents an efficient and practical approach for the development of a highly reliable MXene glucose biosensor, enabling stable and long-term monitoring of glucose levels in human sweat.

Interfacial modulation of Ti3C2Tx MXene using functionalized cellulose nanofibrils for enhanced electrochemical actuation

Electrochemical actuators (ECAs) with low voltage actuation and large deformation ranges generally require electrode materials with high ion kinetic energy transport, high charge storage, and excellent electrochemical-mechanical properties. However, the fabrication of such actuators remains a major challenge. In the present work, hybrid electroactive films were fabricated by self-assembling one-dimensional functionalized cellulose nanofibrils (CNFs) with two-dimensional MXene (Ti3C2Tx). The obtained ECA actuators fabricated by carboxymethylated cellulose nanofibrils (consisting of -CH2COO−surface groups) with Ti3C2Tx integrate excellent curvature (0.1041 mm−1), mechanical strength (21.68 MPa), a bending strain of 0.50 %, and a good actuation displacement of 9.3 mm at a low voltage range of −0.6 to 0.3 V. This may be attributed to the enlarged layer spacing (15.34 Å), which makes the embedding and transport of H+ easier, and excellent adaptivity of mechanical properties achieved by molecular-scaled strong hydrogen bonding, leading to better actuation performance. This study provides a potential research direction for the preparation of ECAs with large actuation deformation.

Carbon matrix NiFeP/C nanoparticles anchored on Ti3C2Tx nanosheets as heterostructure high-performance anode for lithium-ion batteries

Engineered micro-nano heterogeneous architectures for transition metal phosphide (TMPs) anode materials in lithium-ion batteries (LIBs) provide multifunctional active components. These components synergistically interact to address pivotal challenges of pronounced volume expansion and sluggish reaction kinetics within the electrode. Consequently, this engineering design approach significantly enhances the overall battery performance. In this study, a self-assembled approach is employed to integrate hybridized NiFe-PBA nanocubes with two-dimensional (2D) monolayer MXene (Ti3C2Tx), producing a heterostructured NiFeP/C@Ti3C2Tx composite. In this meticulously engineered architecture, the interface between the outer MXene layer and NiFeP embedded within the carbon matrix exhibits several distinct superiorities, such as rapid interfacial ion migration, multidirectional migration pathways, and strong spatial adaptability. The resulting non-uniform phase structure effectively mitigates electrode expansion and enhances electronic conductivity. Consequently, the NiFeP/C@Ti3C2Tx-15 composite demonstrates distinct performance advantages over NiFeP/C without MXene. The composite achieves a specific capacity of 689.4 mAh g⁻¹ at 200 mA g⁻¹ over 300 cycles, double that of NiFeP/C. Furthermore, density functional theory (DFT) calculations validate the electronic conductivity facilitated by the heterointerface between MXene and NiFeP, substantiating the strategic significance of the heterostructure in advancing high-performance anode materials for lithium-ion batteries.

A first-principle study on the two dimensional Janus MXene TaFeC with spin gapless behaviour

Based on density functional theory calculations, we have investigated the two-dimensional Janus MXene TaFeC, focusing particularly on the magnetic and electronic properties. It is found TaFeC is dynamically, mechanically, and thermodynamically stable. With both sizable Curie temperature and enhanced out-off plane magneto-crystalline anisotropy energy, the Janus MXene TaFeC has the potential to be applied at finite temperature. The mechanism behind the magneto-crystalline anisotropy energy and magnetism are explained based on perturbation theory and crystal field splitting, respectively. Under biaxial strain, the ferromagnetic order is robust stable. With a various of effective potential on Fe, the electronic structure evolution is studied, where the effective potential of 1.3 eV is a special case. In such case, the Janus MXene TaFeC can be classified as a new type of spin-gapless semiconductor beyond the previous classifications, behaving topological nontrivial edge states.

Molecular dynamics study of mechanical stability of Ti4C3 MXene subjected to chirality, temperature, strain rate, and point-vacancy for Lithium-ion batteries

Two-dimensional Ti4C3 MXene has recently emerged as a promising electrode for Lithium-ion batteries (LIBs) because of its outstanding ion-transport abilities and high Li-absorbability. This study employed molecular dynamics simulation to explore the mechanical stability of Ti4C3 MXene subjected to various temperatures, strain rates, and vacancy concentrations. A slightly superior tensile strength and elasticity modulus have been observed along zigzag directions, measuring 148.14 GPa and 29.17 GPa, respectively. On the other hand, armchair-oriented Ti4C3 MXene shows a considerably greater fracture strain of 0.259 due to its strain-hardening tendency at lower temperatures. Elevated temperature decreases both fracture strength and fracture strain, which is opposite to the effect of strain rate. Armchair loading has been revealed to be more sensitive to strain rate than its counter direction. Unlike temperature and strain rate, point vacancy significantly deteriorates the elastic modulus of Ti4C3 MXene. Carbon vacancies are more probable than titanium vacancies, which have less formation energy. The atomistic deformation profile supports the predicted values of fracture strain from stress-strain behavior. This in-depth study offers a detailed understanding of the mechanical behavior of Ti4C3 MXene under diverse circumstances, which will aid further experimental study and be beneficial for adopting Ti4C3 as anode materials in LIBs.

Construction of 0-dimensional silver quantum dot/MoSe2@MXene/3-dimensional porous copper foam composite electrodes with heterogeneous interfaces for synergistic electrocatalytic degradation of antibiotics

This study proposes a novel and efficient Ag quantum dots (QDs)/MoSe2@two-dimensional transition metal carbide/nitride (MXene)/copper foam (CF) composite electrode to address the challenge of electrocatalytic degradation of antibiotics in water. The electrode formed a unique electron donor–acceptor system by loading Ag QDs and heterostructured nanosheets on CF, significantly facilitating charge transfer and segregation at the interface. The catalytically active sites at the edges and defective locations of MoSe2 in conjunction with the two-dimensional MXene structure, which formed an efficient electron transfer channel, promoted the electron transfer from the interior to the surface and accelerated the hydrogen adsorption and reduction reactions. Moreover, the charge redistribution at the interface of Ag QDs and MoSe2@MXene formed interfacial dipoles, increasing the active sites on the catalyst surface and promoting the generation of cathodic atomic hydrogen (H*). Under optimal conditions, the degradation rate of tigecycline (TGC) reached as high as 90.1 % ± 2.4 % within 60 min. The anode-generated OH and HClO, along with the cathode-generated H, further promoted the degradation of TGC through co-catalysis. The degradation pathways were analyzed using density-functional theory (DFT) calculations and liquid chromatography-mass spectrometry (LC-MS) techniques. Moreover, toxicity analysis of the degradation products was carried out to ensure the safety of the treated wastewater discharge. A reflux continuous effluent reactor was also designed to achieve high degradation efficiency and low energy consumption after stable operation, laying the foundation for industrial applications. This technology provides new ideas for the design of green, efficient, stable, and low-consumption electrocatalytic reactors and contributes to a sustainable future environment.

Two-dimensional MXene Nanosheets and their Composites for Antibacterial Textiles: Current Trends and Future Prospects

Abstract: As a novel two-dimensional (2D) nanosheet (NS), MXene has attracted attention in antibacterial applications due to its excellent high surface area, remarkable hydrophilicity, strong flexibility, and excellent antibacterial properties. This review intends to provide valuable insight into the further development of antibacterial MXenes and their composite materials. In this paper, we review the antibacterial mechanisms of MXenes and their composite materials and summarize the research progress of antibacterial finishing fabrics, fibers and dressings based on MXene NSs. Due to the rich oxygen-containing groups, 2D MXene NSs and its composites exhibited significant antibacterial activity against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis so they have been widely used in antibacterial textiles including finishing fabrics, fibers, and dressings. 2D MXene NSs have showed some antibacterial properties based on cell experiments or blood tests. The antibacterial mechanisms mainly include physical sterilization and chemical oxidative stress sterilization. The future direction of antibacterial textiles based on MXenes was proposed.