MXene Layers Research Articles

Flexible and free-supporting Prussian blue analogs /MXene film for high-performance sodium-ion batteries

Sodium-ion batteries are the most promising alternative to lithium-ion batteries because of their low cost and environmental friendliness. Prussian blue analogs (PBAs) have attracted the attention of researchers because of their open skeleton structure and abundant redox active sites. However, the interstitial water in its crystal structure and poor electron conductivity limit its performance in sodium-ion batteries. A flexible self-supporting electrode is prepared by anhydrous preparation in a ball mill and simple filtration method. The high surface area nanoparticles and the high flexibility MXene layer in the electrode adapt to the rapid Na+ dynamics, alleviating the electrode expansion. The formation of a NaF-rich cathode-electrolyte interface (CEI) layer on the electrode surface inhibits the erosion of active substances by electrolyte, reduces the capacity attenuation of the electrode, and enhances the cyclic stability of the electrode. Electrode without a conductive agent and binder shows excellent electrochemical performance. The discharge capacity of the electrode is 58.3 mAh g−1at 1000 mA g−1 current density, and the capacity retention rate is 59.7% after 1000 cycles. This work has implications for the design of the next generation of low-cost, flexible, and fast charge and discharge energy storage devices.

Balancing MXene Surface Termination and Interlayer Spacing Enables Superior Microwave Absorption

AbstractSurface chemistry and interlayer engineering determines the electrical properties of 2D MXene. However, it remains challenging to regulate the surface and interfacial chemistry of MXene simultaneously. Herein, simultaneous modulation of Ti3C2Tx MXene surface termination and layer spacing by alkali treatment are achieved. The electrical and electromagnetic properties of Ti3C2Tx are investigated in detail with respect to KOH and ammonia concentration dependence. A high concentration of KOH caused the Ti3C2Tx layer spacing to expand to 13.7 Å and the surface O/F ratio to increase to 33.84. Because of its weaker ionization effect, ammonia provides finer tuning compared to the drastic intercalation of KOH with a thorough sweeping of the F‐containing groups. Ti3C2Tx is enriched with conductive ‐OH termination after ammonia treatment, which achieves an effective balance with the increased interlayer resistance. Therefore, NH3H2O‐Ti3C2Tx achieves broad‐band impedance matching and exhibits an efficient microwave loss of −49.1 dB at a low thickness of 1.7 mm, with an effective frequency bandwidth of 3.9 GHz. The results herein optimize the electrical properties of Ti3C2Tx using surface and interfacial chemistry to achieve broad microwave absorption, providing a framework for enhancing the electromagnetic wave loss of intrinsic MXene.

Effect of surface functional groups on MXene conductivity.

We report the in-plane electron transport in the MXenes (i.e., within the MXene layers) as a function of composition using the density-functional tight-binding method, in conjunction with the non-equilibrium Green's functions technique. Our study reveals that all MXene compositions have a linear relationship between current and voltage at lower potentials, indicating their metallic character. However, the magnitude of the current at a given voltage (conductivity) has different trends among different compositions. For example, MXenes without any surface terminations (Ti3C2) exhibit higher conductivity compared to MXenes with surface functionalization. Among the MXenes with -O and -OH termination, those with -O surface termination have lower conductivity than the ones with -OH surface terminations. Interestingly, conductivity changes with the ratio of -O and -OH on the MXene surface. Our calculated I-V curves and their conductivities correlate well with transmission functions and the electronic density of states around the Fermi level. The surface composition-dependent conductivity of the MXenes provides a path to tune the in-plane conductivity for enhanced pseudocapacitive performance.

Tuning the Hydroxyl Density of MXene to Regulate the Electrochemical Performance of Anchored Cobalt Phthalocyanine for CO2 Reduction.

Precise electronic state regulation through coordination environment optimization by metal-support interaction is a promising strategy to facilitate catalysis reaction, while the limited density of functional groups in the bulk substrate restricts the regulation degree. Herein, different sizes of Ti3C2Tx MXene with hydroxyl (-OH) terminal including the MXene layer (ML-OH, 3 μm), the MXene nanosheet (MNS-OH, 600 nm), and the MXene quantum dot (MQD-OH, 8 nm) were prepared to anchor CoPc, and the effect of -OH density on the performance of electrochemical CO2 reduction was systematically investigated. Notably, a linear relationship was established by plotting reactivity vs hydroxyl density. With the highest -OH density, CoPc/MQD-OH exhibits a superior Faradaic efficiency for CO formation (FECO) of ∼100% at -0.9 to -1.0 V vs RHE and a high FECO of >90% over a wide potential window from -0.8 to -1.4 V. The mechanism exploration shows that the axial coordination interaction of the -OH terminal with Co increases the electron density of the Co site, thus promoting the adsorption and activation of CO2. This work provides a new insight into designing of molecular catalysts with high efficiency and tunable structure for other electrochemical conversions.

Nano metal oxide-intercalated MXene in-situ prepared by irradiation as effective electromagnetic wave absorbents

With the rapid development of electronic communication technology, electromagnetic pollution has become increasingly severe, leading to a growing need for absorption materials with excellent absorption performance. Herein, nano-sized oxide-intercalated Ti3C2T x MXene composites were synthesized via γ-radiation in an aqueous system. The synthesis was conducted in a reducing environment at room temperature, which effectively prevented the oxidation of MXene. Nano-oxides (Fe2O3 and Cu2O) were formed in situ between the MXene layers, forming a homogeneous oxide-intercalated structure. Compared with the original MXene, the intercalated structure significantly enhanced the electromagnetic wave absorption (EMA) performance of the MXene/Fe2O3 composite in the frequency range of 2–18 GHz, with smaller reflection loss (RL) (−58.7 dB), thinner thickness (2.35 mm). The RLmin value of the MXene/Cu2O composite was −50.9 dB (2.55 mm) and the effective frequency width was 4.88 GHz at a thickness of 1.3 mm. Compared with ordinary chemical methods, the γ-radiation is a facile and ‘green’ method that is suitable for large-scale preparation. The absorption mechanism was attributed to conductive loss, polarization loss, and magnetic loss, which contributed to efficient EMA. This work demonstrates that γ-radiation is a promising method for preparing nano metal oxide-intercalated MXene with enhanced EMA performance.

Fabrication of Ti3C2 MXene and tetradecylphosphonic acid@MXene and their excellent friction-reduction and anti-wear performance as lubricant additives

MXene is a kind of two-dimensional material with a graphene-like structure. However, the low productivity and oil solubility of MXene limit its use as a lubricant additive. Herein, a simplified strategy for exfoliating multilayer-MXene via water-molecules-assisted intercalation approach is proposed. MXene and tetradecylphosphonic acid (TDPA)@MXene sheets were prepared as lubricant oil additives by chemical etching and surface modification with TDPA. The as-prepared additives added to PAO8 ensured friction-reduction and wear resistance at contact pressures less than 1.4 GPa, which was attributed to the iron-oxide and FePO4 tribochemical reaction film and lower interlaminar shear between the MXene layers. This study presents methods for improving the productivity and functional applications of MXene, enriching the existing research on MXene as a lubricant additive.

Investigating the effect of surface termination and thickness of MXene on the detection response of the SPR sensor using FDTD simulation

Surface plasmon resonance (SPR) is an optical-based detection technique that is of great interest in research because of its rapid detection and label-free features. Current SPR sensor development focuses on modifying the sensing surface for maximum bioreceptor and target immobilization. In this research, we proposed SPR sensor with the Kretschmann configuration modified by adding immobilization layers using a few layers of MXene (Ti3C2T2). MXene is an alternative two-dimensional material suitable for sensors because it has surface termination (T2) which active to immobilize the target. The different surface termination (T=O,OH,F) and number of MXene layers was added on the SPR sensor to obtained the optimum parameters of MXene application. Using Finite-Difference Time-Domain (FDTD) method, the SPR sensor is simulated on a different refractive index background which is assumed as the analyte. The different surface termination produces different SPR curves at the same refractive index conditions, the changes are found in the position of the SPR angle and the width of the curve. Thus, the results of surface termination variations are evaluated based on the full-width half-maximum (FWHM) of the curve which indicates the detection accuracy. Meanwhile, the optimum number of MXene layers was evaluated from the sensitivity value of the MXene-modified SPR sensor to changes in refractive index from 1.33 to 1.34. The result shows that the optimum detection performance was obtained from the application of six layers MXene with surface termination F2(Ti3C2F2). This configuration resulted a sensitivity of 150.131°/RIU and the LOD is 0.01633 RIU.

Interfacial properties and strengthening mechanisms of few-layered MXene reinforced Mg-based composites

In the present study, MXene-reinforced Mg matrix composites were manufactured via the electrostatic self-assembly protocol and spark plasma sintering (SPS) process to develop lightweight materials with high mechanical performance. Uniform dispersion of MXene sheets was achieved in MXene/AZ91 composites. A unique interfacial structure was confirmed in these composites, which exhibited an ultrafine MgO interlayer (grain size of ∼10 nm) coherently incorporated or intercalated into MXene layers. The unique interfacial structure contributed to robust interfacial bonding between MXene sheets and Mg matrix, resulting in a substantial mechanical performance enhancement. The yield strength of 325.3 ± 7.9 MPa and elongation of 8.8 ± 0.2% were achieved in 0.3vol% MXene/AZ91 composites, showing a significantly high strengthening efficiency of 159.1 without sacrificing ductility. Quantitatively investigation of strengthening behavior manifested that the load-transfer effect was the primary strengthening mechanism in MXene/AZ91 composites, and the simulated strength was well-matched with experimental results due to the special interfacial structure and excellent dispersion properties. This study could offer significant guidance for developing novel lightweight materials with high mechanical performance for structural applications.

Highly conductive, hydrophobic, and acid/alkali-resistant MXene@PVDF hollow core-shell fibers for efficient electromagnetic interference shielding and Joule heating

To endow transition metal carbide (MXene) fibers with satisfactory chemical resistances, high electrical conductivity and enhanced ductility, multifunctional hollow core-shell fibers with ductile polyvinylidene fluoride (PVDF) shell and compactly ordered MXene hollow core are fabricated with a coaxial wet-spinning assembly strategy. The partial hydroxylation of the PVDF occurred during the coagulation in the presence of ammonium hydroxide enhances the interfacial interaction of the PVDF layer with the MXene layer. The hollow core consisting of compact and ordered MXene layer provides the fibers with a high electrical conductivity of 3.08 × 105 S m−1, while the PVDF shell endows the fibers with enhanced ductility and excellent resistances to acid, alkali, and seawater. The hollow core-shell structure makes the fiber lightweight, and facilitates multiple scattering of electromagnetic waves, resulting in increased electromagnetic wave absorption and attenuation. The ductile and conductive textile made of the hollow core-shell fibers with a 6 μm-thick MXene layer exhibits a high electromagnetic interference shielding effectiveness of ∼60 dB. Moreover, the resultant fibers exhibit exceptional Joule heating performances for human thermal management. The high conductivity, enhanced ductility, strong chemical resistances, and satisfactory Joule heating properties make the hollow core-shell fibers promising for electromagnetic interference shielding and wearable heating applications.

Resistive-type sensors based on few-layer MXene and SnO2 hollow spheres heterojunctions: Facile synthesis, ethanol sensing performances

High-performance and low-cost gas sensors are highly desirable and involved in industrial production and environmental detection. The combination of highly conductive MXene and metal oxide materials is a promising strategy to further improve the sensing performances. In this study, the hollow SnO2 nanospheres and few-layer MXene are assembled rationally via facile electrostatic synthesis processes, then the SnO2/Ti3C2Tx nanocomposites were obtained. Compared with that based on either pure SnO2 nanoparticles or hollow nanospheres of SnO2, the SnO2/Ti3C2Tx composite-based sensor exhibits much better sensing performances such as higher response (36.979), faster response time (5 s), and much improved selectivity as well as stability (15 days) to 100 ppm C2H5OH at low working temperature (200 °C). The improved sensing performances are mainly attributed to the large specific surface area and significantly increased oxygen vacancy concentration, which provides a large number of active sites for gas adsorption and surface catalytic reaction. In addition, the heterostructure interfaces between SnO2 hollow spheres and MXene layers are beneficial to gas sensing behaviors due to the synergistic effect.

Improvement in hydrogen storage performance of Mg by mechanical grinding with molten salt etching Ti3C2Clx

Mg-based materials are currently a hot research topic as hydrogen storage materials due to their considerable theoretical hydrogen storage capacity. However, the kinetic performance of hydrogen absorption and desorption of Mg is too slow and requires high temperature, which seriously hinders the application of this material. MXene is a new type of two-dimensional material with significant role in improving thermodynamics and kinetics. In this experiment, a two-dimensional layered MXene containing Cl functional group was prepared by molten salt etching using the Ti-containing MAX phase as the raw material. Then different ratios of Ti3C2Clx were uniformly dispersed onto the surface of Mg by high energy ball milling. The samples were characterized by hydrogen absorption and desorption kinetics, SEM, XRD, XPS, and DSC to investigate the effect of Ti3C2Clx on the hydrogen absorption and desorption performance of Mg. The onset hydrogen absorption temperature can be reduced to room temperature and the hydrogen release temperature is reduced by 200 ​°C by doping Ti3C2Clx. And there is also 5.4 ​wt% hydrogen storage in the isothermal hydrogen absorption test at 400 ​°C. The results of DSC demonstrate that the Ea of Mg+15 ​wt% Ti3C2Clx was reduced by 12.6% compared to pristine Mg. The ΔH is almost invariable. The results of XPS show that the presence of multivalent Ti promotes electron transfer and thus improves the conversion between Mg2+/Mg and H−/H. This study provides a guideline for further improving the hydrogen absorption and desorption performance of Mg-based hydrogen storage materials.

Synthesis of stable titanium carbide MXene nanocomposites using crosslinker nanoparticles for flexible supercapacitors: A novel and cost-effective approach

This study presents a novel and cost-effective silver nanoparticles (AgNPs)-based cross-linking approach to synthesize AgNPs-decorated reduced graphene oxide (Ag@RGO) and its stable nanocomposites (NCs) with titanium carbide MXene for flexible supercapacitors (SCs). MXene/Ag@RGO NCs showed enhanced electrochemical performance compared to individual MXene. The electrostatic interactions between positively charged AgNPs@RGO and negatively charged MXene stabilized the assembly of 2D layers. Moreover, the presence of AgNPs played a crucial role in maintaining an optimal distance between the layers of two-dimensional (2D) MXene. This distance helped to prevent restacking of the MXene layers and ensured the interlayer ionic flow unimpeded, promoting efficient charge transport. In conclusion, the stable self-assembly of these 2D-2D structures holds significant potential for high-performance supercapacitor (SC) electrodes. The prepared NCs demonstrated specific capacitance (Csp) of ∼630 F/g which is 9.6 and 3.5 times better than pure MXene and MXene/RGO, respectively, along with only a 0.12% decrease in Csp after 1000 C V cycles (1.97% decrease after 5000 GCD cycles). Overall, this study proposes an interesting idea to explore stabilized nanocomposite structures for next-generation flexible SCs.

Ion-sieving Janus separator modified by Ti3C2Tx toward dendrite-free zinc-ion battery

Aqueous zinc-ion batteries, as one of the promising substitutes for lithium-ion batteries, have received increasing attention due to their high safety, low cost, and non-toxicity. Nevertheless, the inevitable growth of zinc dendrites, hydrogen evolution, and side reactions on the Zn anode greatly hinder the further application of zinc-ion batteries. The current solutions mainly focused on electrolyte regulation, artificial interface layer introduction, and zinc alloy anode construction. MXene, as a novel generation of two-dimensional layered transition metals carbides/ nitrides, has been widely investigated in a variety of metal ion batteries in the last decade owing to excellent physical and chemical properties. Herein, we constructed an ion-sieving Janus separator for the aqueous zinc-ion battery by spraying Ti3C2Tx MXene ink on one side of the commercial glass fiber separator. Because of the advantages of MXene such as high conductivity, abundant surface functional groups, and highly matched lattice constants with the Zn anode, the composite separator can homogenize the surface electric field of the Zn anode, optimize the flux of Zn2+, and induce the uniform deposition of Zn2+. Most importantly, a unique ion sieving function was realized in the electrolyte because of the intrinsic electro-negativity of the MXene layer. The concentration of H+ and SO42- on the Zn anode side is largely reduced, and the hydrogen evolution and side reactions are greatly inhibited. Thus, for symmetrical cells, an ultralong cycling lifespan up to 2500 h and superior rate capability with dendrite-free deposition behavior were achieved. When further applying the Janus separator to aqueous zinc-ion batteries combined with the fabricated α-MnO2 cathode, Zn anode, and 2 M ZnSO4 + 0.2 M MnSO4 electrolyte, a superb capacity retention rate (85.7%) upon cycling for 500 cycles at 1.0 A g−1 was obtained. This ion-sieving separator possesses the giant potential for zinc-ion batteries.

Design of 2D/2D heterostructure by coupling cobalt hydroxides with Mxene on nickel foam for high energy density supercapacitors

Two-dimensional (2D) layered transition metal compounds are promising pseudocapacitive materials for high-performance supercapacitors. Herein, the cobalt hydroxide coupled Ti3C2Tx MXene layers on nickel foam (Co(OH)2-Ti3C2Tx@NF) is prepared by the facile hydrothermal method. The 2D/2D heterostructures by coupling layered double hydroxide (LDH) with MXene can expose the more specific surface area and boost the redox-active sites. Co(OH)2-Ti3C2Tx@NF exhibits a higher specific capacitance (1400 F g−1) than Co(OH)2@NF (1106 F g−1) and Ti3C2Tx@NF (844 F g−1), and the capacitance retention is 98.2 % after 10,000 cycles implying outstanding cyclic stability. Excellent pseudocapacitive behavior is assigned to the redox reaction by the interaction of MXene with alkali metal ions and the valence variations of Co3+/Co2+. Furthermore, the assembled asymmetric Co(OH)2-Ti3C2Tx@NF//AC supercapacitor shows an energy density of 13.7 μWh cm−2 at 1.4 mW cm−2. These results imply that the LDH/MXene hybrid with 2D/2D heterostructures can be considered promising pseudocapacitive electrode materials for high-energy supercapacitors.

Exploring the potential of MXene nanoslit for water desalination through molecular dynamics simulations

The charge features of nanoslit were deemed to exert significant influences on optimization of its desalination performance. The MXene nanoslit carries richness of charge features, thus it should possess exceptional desalination performance. However, the optimal application conditions of MXene nanoslit as a water desalination membrane has not been systematically explored. In this work, we adopted molecular dynamics (MD) methods to assess the desalination performance of Ti3C2TX nanoslits. The influence factors, including the termination group, the slit width, temperature, pressure, and thickness were discussed with the expectation of probing the optimal application conditions for MXene nanoslit membranes. Simulation results showed that MXene nanoslit possesses excellent desalination performance thanks to the charge features of the nanoslit channel. The increase of slit width, temperature, and pressure all promote the water permeance but deteriorate the ion rejection performance. Fortunately, the tradeoff between water permanence and ion rejection rate can be mediated by the termination groups. The increase of MXene layer number could effectively improve the desalination performance, taking both water flux and ion rejection performance into account. The present work might provide some valuable suggestions for the design of water desalination membranes with exceptional desalination performance by manipulating the electrostatic properties of membranes.

Multi-ion competition mechanism within MXene interlayer and Li ion intercalated electrode function

2D layered MXene material offers atomic level intervals that can expand the function of ion intercalated electrode. Challenges remain in modulating the interlayer environment and overcome the problem of lamellar stacking. Herein, to accurate control the interlayer structure of MXene and understand these ions confined by MXene, Li+, Na+ and K+ are pre-inserted into the inner space, which is the spaced voids of two adjacent Ti3C2Tx MXene layers with Al3+ ions, and the relationship between the interlayer spacing and the multi-ion interaction mechanism is explored. Furthermore, the electrochemical behavior and performance induced by multi-ion intercalated MXene electrodes are evaluated. The results show that the capacity of MXene electrodes with Na+ pre-intercalation obtained a capacity of 250.80 mAh g−1, and the capacity is maintained after 200 cycles is 179.67 mAh g−1, which attenuation is 28.36%. In addition, the pre-intercalated Na+ ions can maintain a more stable structure and benefit to electrochemical cycling performance than these pre-intercalated Li+ ions occupying the transport channels of the electrolyte ion. It provides data support for in-depth understanding of the mechanism and derivation of ion pre-intercalated MXene.

Multi-weather full-body triboelectric garments for personalized moisture management and water energy acquisition

The occurrence of extreme events (such as heatwaves, heavy precipitation) is unprecedented in the observed record and will increase with increasing global warming, leading to severe human health issues. Wearing suitable garments in different weather is one of the solutions for people to ease their physical discomfort in an energy-saving way. However, only one piece of traditional clothes hardly satisfies the demand of the changing weather. Herein, a multi-weather full-body triboelectric garment with a one-way moisture transport structure is presented to keep people feeling cool in the scorching weather while capturing droplet energy in rainy situations. A trilayer progressive wetting structure was designed to effectively transport sweat from the inner layer near the skin to the outer layer to keep the skin dry and comfortable in the muggy air, with a unidirectional transmission index of 1025%. When it starts to rain, the rain droplets quickly roll down the textile surface and generate triboelectric energy with the hydrophobic surface and conductive MXene layer inside. More than that, the scalable fabrication process makes it possible to obtain the textile with enough areas for making a whole garment, which is much more practical in real application scenarios.

Thickness-dependent catalytic activity of hydrogen evolution based on single atomic catalyst of Pt above MXene

Hydrogen as the cleanest energy carrier is a promising alternative renewable resource to fossil fuels. There is an ever-increasing interest in exploring efficient and cost-effective approaches of hydrogen production. Recent experiments have shown that single platinum atom immobilized on the metal vacancies of MXenes allows a high-efficient hydrogen evolution reaction (HER). Here using ab initio calculations, we design a series of substitutional Pt-doped Ti n + 1C n T x (Ti n + 1C n T x -PtSA) with different thicknesses and terminations (n = 1, 2 and 3, T x = O, F and OH), and investigate the quantum-confinement effect on the HER catalytic performance. Surprisingly, we reveal a strong thickness effect of the MXene layer on the HER performance. Among the various surface-terminated derivatives, Ti2CF2-PtSA and Ti2CH2O2-PtSA are found to be the best HER catalysts with the change of Gibbs free energy ΔG H* ∼ 0 eV, complying with the thermoneutral condition. The ab initio molecular dynamics simulations reveal that Ti2CF2-PtSA and Ti2CH2O2-PtSA possess a good thermodynamic stability. The present work shows that the HER catalytic activity of the MXene is not solely governed by the local environment of the surface such as Pt single atom. We point out the critical role of thickness control and surface decoration of substrate in achieving a high-performance HER catalytical activity.

Bioinspired multi-stimulus responsive MXene-based soft actuator with self-sensing function and various biomimetic locomotion

Although a series of outstanding achievements have been realized so far, developing soft actuators that can respond to various stimuli and simulate biological versatility (e.g., self-sensing function, diverse locomotion, etc.) is still a great challenge. Here, by utilizing internal stress generated spontaneously during the preparation process, an originally rolled MXene/polydimethylsiloxane (PDMS) bimorph soft actuator has been designed and fabricated. Based on the outstanding photothermal/electrothermal conversion efficiency and adjustable interlayer d-spacing change of Ti3C2Tx MXene, and the large thermal/chemical vapor expansion of crosslinked PDMS, this actuator can produce reversible large deformation under various forms of stimulus, including heat, light, electric, and n-hexane vapor. More importantly, microcracks can be formed spontaneously on the surface of MXene layer during the fabrication process of the actuator, which causes the resistance of MXene layer to be very sensitive to mechanical deformation. Based on this, a light-driven artificial tongue is fabricated, which not only mimic the ejection motion and catching prey behavior of the frog’s tongue, but also perceive the touching object. Moreover, a series of sophisticated biomimetic locomotion such as jumping, crawling, and self-oscillation all can be realized by using this soft actuator. Besides, the actuator with rolled initial structure can also be an intelligent gripper with low energy consumption. By doping Fe3O4 nanoparticles in PDMS matrix, the composite actuator can carry object to through complex maze in adjustable magnetic field without additional stimulation. This MXene-based actuator provides new insights in design of next generation of smart actuators with multi-functions and multiform motions.

Simultaneously improving the EMI shielding performances and mechanical properties of CF/PEKK composites via MXene interfacial modification

In this study, two-dimensional MXene (Ti3C2Tx) was employed to modify the interface of carbon fiber-reinforced polyetherketoneketone (CF/PEKK) composites, in order to simultaneously improve the electromagnetic interference (EMI) shielding performances and mechanical properties. The obtained CF/PEKK composites possessed outstanding EMI and mechanical performances, as anticipated. Specifically, the CF/PEKK composites modified with MXene at 1 mg mL–1 exhibited an excellent EMI shielding effectiveness of 65.2 dB in the X-band, a 103.1% enhancement compared with the unmodified CF/PEKK composites. The attractive EMI shielding performances of CF/PEKK composites originated from enhanced ohmic losses and multiple reflections of electromagnetic waves with the help of the MXene and CF layers. In addition, CF/PEKK composites achieved the best mechanical properties by optimizing the dispersion concentration of MXene to 0.1 mg mL–1. The flexural strength, flexural modulus, and interlaminar shear strength of CF/PEKK composites reached 1127 MPa, 81 GPa, and 89 MPa, which were 28.5%, 9.5%, and 29.7% higher than that of the unmodified CF/PEKK composites, respectively. Such improvement in mechanical properties could be ascribed to the comprehensive effect of mechanical interlocking, hydrogen bonds, and Van der Waals forces between the introduced MXene and CF, PEKK, respectively.