Multilayered MXene Research Articles

MXene–MWCNT Conductive Network for Long-Lasting Wearable Strain Sensors with Gesture Recognition Capabilities

In this work, a conductive composite film composed of multi-walled carbon nanotubes (MWCNTs) and multi-layer Ti3C2Tx MXene nanosheets is used to construct a strain sensor on sandpaper Ecoflex substrate. The composite material forms a sophisticated conductive network with exceptional electrical conductivity, resulting in sensors with broad detection ranges and high sensitivities. The findings indicate that the strain sensing range of the Ecoflex/Ti3C2Tx/MWCNT strain sensor, when the mass ratio is set to 5:2, extends to 240%, with a gauge factor (GF) of 933 within the strain interval from 180% to 240%. The strain sensor has demonstrated its robustness by enduring more than 33,000 prolonged stretch-and-release cycles at 20% cyclic tensile strain. Moreover, a fast response time of 200 ms and detection limit of 0.05% are achieved. During application, the sensor effectively enables the detection of diverse physiological signals in the human body. More importantly, its application in a data glove that is coupled with machine learning and uses the Support Vector Machine (SVM) model trained on the collected gesture data results in an impressive recognition accuracy of 93.6%.

Functionalized 2D multilayered MXene for selective and continuous recovery of rare earth elements from real wastewater matrix.

Rare earth elements (REEs) are the "fuel" for high-tech industry, yet their selective recovery from complex waste matrices is challenging. Herein, we designed a 2D multilayered MXene Ti3C2Tx adsorbent for selective extraction of REEs in a broad pH range. By establishing strong Lewis acid-base interactions, extraction capacities of Ti3C2Tx to Eu(III) and Ho(III) reached 892.8 and 649.2 mg/g, respectively, even at pH 2.0. Following the Valence Matching Principle, the Ti3C2Tx adsorbent also demonstrated high selectivity for recovery of various REEs from real REEs processing wastewater and actual sludge from magnet manufacturing industry. To demonstrate the practical feasibility, a layer-stacked membrane of Ti3C2Tx supported on polyethersulfone substrate was fabricated for continuous recovery of REEs and exhibited excellent removal of Eu(III) (99.1 % at pH 5.0), showcasing its potential for large-scale applications. DFT calculations and material characterization demonstrated that chemisorption between Lewis acid (REEs cations) and Lewis base (F and O) sites is the main adsorption process involved in the uptake of Eu(III) and Ho(III). Finally, both the Ti3C2Tx adsorbent and membrane were successfully regenerated and reused via simple acid wash. Overall, the results demonstrate the Ti3C2Tx-based recovery as a promising path for sustainable harvesting of REEs.

Microwave Sensor with Light-Assisted Enhancement Based on Ti3C2Tx MXene: Toward ppb-Level NO2 Detection Limits.

Chemiresistive sensors are currently the most popular gas sensors, and metal semiconductor oxides are often used as sensitive materials (SMs). However, their high operating temperature means that more energy is required to maintain normal operation of the SM, resulting in an increase in power consumption of the entire sensing system. In order to solve this problem, a microwave gas sensor embedded with multilayer Ti3C2Tx MXene and split ring resonator (SRR) for nitrogen dioxide (NO2) detection was reported in this work. The sensor takes advantage of the weak coupling between the two SRRs to achieve a highly concentrated electric field and high Q-factor, in which the weak coupling region serves as the sensitive region to avoid damage to the resonator structure caused by the excessive conductivity of Ti3C2Tx. The sensor has good selectivity, a lower detection limit of 2 ppb, with an average detection sensitivity of 98.66 mdB ppm-1 in the range of 2-10,000 ppb at room temperature. Additionally, the effect of different lighting source to the sensor performance is investigated, and the sensor reached the best response (1.54 dB) under blue light. Finally, the mechanism of the enhanced sensitivity is discussed in detail based on the results of simulations and tests. The sensor circuit designed in this work provides a new approach for MGSs and for the first time introduces the photocatalytic pathway into microwave sensors, which will contribute to the optimization of microwave gas sensors in the future.

Regulative Fe‐3d Orbitals via Lying‐Down Conformation of Metalorganic Molecules‐Axially Coordinated MXene for Rechargeable Zn–Air Batteries

AbstractA bifunctional electrocatalyst is developed, exhibiting high catalytic activity and reversibility for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through a regulative Fe d‐orbital engineering strategy. In this strategy, iron phthalocyanine organic molecule (FeOM) crystals are axially coordinated onto multilayer Mo2CTx MXene (FeOM‐Mo2CTx), adopting a lying‐down conformation. This hybridization fosters unique electronic guest–host interactions, with FeOM donating charge to Mo2CTx via Fe−O bonding, leading to symmetry breaking in electronic distribution and modified delocalization of Fe‐3d charge, accompanied by a Fe(II) spin‐state transition. These transformations enhance the adsorption and desorption toward oxygenated intermediates, optimizing the *OOH−*O transition to boost the reversibility of ORR and OER kinetics. The FeOM‐Mo2CTx exhibits a favorable ORR half‐wave potential of 0.961 V and a minimal OER overpotential of 349 mV at 10 mA cm−2 in 1.0 m KOH. The assembled aqueous zinc‐air battery (ZAB) achieves a peak power density of 155.3 mW cm−2 and exceptional charge–discharge durability over 1500 h, outperforming a conventional (Pt/C + RuO2) system. Overall, the findings underscore the significance of electronic structural engineering of FeOM with Mo2CTx, paving the way for innovative air cathodes in the development of rechargeable ZABs with enhanced performance and cost‐effectiveness.

(Invited) Slit Pores Engineering in 2D Layered MXenes for Electrochemical Energy Storage and Conversion

MXenes constitute a diverse family of 2D transition metal carbides/nitrides, characterized by the formula Mn+1XnT x (where M represents an early transition metal, X denotes carbon or nitrogen, n ranges from 1 to 4, and T x indicates surface terminations). Their exceptional electrical conductivity and ion-hosting capacity make them outstanding candidates for electrode materials in electrochemical energy storage systems. The interlayer spacing in MXenes can be considered as tunable slit pores. While intercalation plays a pivotal role in the applications of MXenes as a mechanism for ion storage, the impact of pre-intercalation on their electrochemical performance is not well understood. In this context, we will discuss several examples where pre-intercalation and slit pores engineering have significantly altered the electrochemical behavior of MXenes. Manipulating Ti3C2T x MXene multilayers through pre-intercalation has yielded an ultra-high areal capacitance of up to 5.7 F/cm2—a record for MXenes. Notably, engineering the slit pores through pre-intercalation, with an interlayer spacing of approximately 2.2 nm, has achieved a capacitance of 257 F/g—an order of magnitude higher than that of pristine MXene—across a voltage window exceeding 3V in pure EMIMTFSI electrolyte. This outcome results in a high-energy density comparable to batteries without compromising their impressive power density. The slit pores in MXenes can also support the growth of other nanomaterials such as nitrogen-doped carbon sheets. The hybrid of Ti3C2T x with confined nitrogen doped carbon in the slit pores have demonstrated a reversible sodium-ion specific capacity of 305 mAh/g at a specific current of 20 mA/g, 2.3 times that of pristine multilayer MXene. For Li-ion batteries, a reversible capacity of 400 mAh/g at a specific current of 20 mA/g has been achieved, which is 1.5 times that of Ti3C2T x MXene.

Construction of SrTiO3/Ti3C2/TiO2 Z-scheme derived from multilayer Ti3C2 MXene for efficient photocatalytic overall water splitting

Constructing a Z-scheme system is one of the promising approaches for facilitating the separation and transfer of photogenerated carriers and obtaining the admirable photocatalytic activity. However, due to the similar material system and band alignment in type-II and Z-scheme, obtaining a favorable Z-scheme is a significant challenge. In this work, an in-situ construction of SrTiO3/Ti3C2/TiO2 Z-scheme is presented using a two-step hydrothermal method with multilayer Ti3C2 as the Ti source. This in-situ growth strategy, which utilizes the intrinsic Ti source of Ti3C2, enables the construction of the SrTiO3/Ti3C2/TiO2 Z-scheme through the enhanced interfacial ohmic contacts between SrTiO3, highly conductive Ti3C2 and TiO2 at the atomic level. The obtained SrTiO3/Ti3C2/TiO2 (SMT-3) sample shows a remarkable enhancement in photocatalytic overall water splitting performance compared with SMT-1 and SMT-10 samples. This work provides an alternative strategy for constructing a highly efficient Z-scheme for photocatalytic overall water splitting.

Scalable, High‐Yield Monolayer MXene Preparation from Multilayer MXene for Many Applications

AbstractMXene (Ti3C2Tx) is renowned for its exceptional conductivity and hydrophilicity; however, the low yield of monolayers hinders its industrial scalability. Herein, we present a strategy to substantially enhance the monolayer yield by disrupting the hydrogen‐bonding cage confinement of multilayer MXene using high‐temperature ultrasound, challenging the conventional belief that monolayer MXene can only be prepared at lower temperatures. At approximately 70 °C, the weakened hydrogen bonding between the oxygen‐containing terminal groups of multilayer MXene and surrounding water molecules weakens the hydrogen‐bond cage confinement. This enables ultrasonic cavitation to generate more microbubbles that penetrate the interlayers of multilayer MXene, resulting in gentle and thorough delamination into larger monolayer nanosheets. Achieving up to a 95 % yield in just tens of minutes, these nanosheets exhibit properties comparable to those produced by traditional ice‐bath methods. Furthermore, the high‐concentration MXene ink produced on a large scale using this high‐yield approach exhibits excellent printing and processing capabilities, and the corresponding products showcase superior infrared stealth and Joule heating characteristics. This work addresses a key technical bottleneck in MXene production, paving the way for its extensive technological and industrial applications.

Scalable, High-Yield Monolayer MXene Preparation from Multilayer MXene for Many Applications.

MXene (Ti3C2Tx) is renowned for its exceptional conductivity and hydrophilicity;however,the low yield of monolayers hinders its industrial scalability. Herein, wepresent a strategy to substantially enhance the monolayer yield by disrupting thehydrogen-bonding cage confinement of multilayer MXene using high-temperature ultrasound,challengingthe conventional belief that monolayer MXene can only be prepared at lower temperatures. At approximately70 °C, the weakened hydrogen bondingbetween the oxygen-containing terminal groups of multilayer MXene and surrounding water molecules weakensthe hydrogen-bond cage confinement. Thisenables ultrasonic cavitation to generate more microbubbles thatpenetrate the interlayers of multilayer MXene,resultingin gentle and thorough delamination into larger monolayer nanosheets.Achieving up to a 95%yield in just tens ofminutes,these nanosheets exhibit properties comparableto those producedbytraditional ice-bath methods. Furthermore, the high-concentration MXene ink produced on a large scale using this high-yield approachexhibits excellent printing and processingcapabilities, and the correspondingproducts showcase superior infrared stealth and Joule heating characteristics. This work addresses a keytechnical bottleneck inMXene production, paving the way for its extensive technological and industrial 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.

Preparation of interconnected tin oxide nanoparticles on multi-layered MXene for lithium storage anodes

MXenes, a novel class of two-dimensional (2D) materials known for their excellent electronic conductivity and hydrophilicity, have emerged as promising candidates for lithium-ion battery anodes. This study presents a simple wet-chemical method for depositing interconnected SnO2 nanoparticles (NPs) onto MXene sheets. The SnO2 NPs act as both a high-capacity energy source and a spacer to prevent MXene sheets from restacking. The highly conductive MXene facilitates rapid electron and lithium-ion transport and mitigates the volume changes of SnO₂ during the lithiation/delithiation process by confining the SnO₂ NPs between the MXene layers. This composite anode, SnO2@MXene, leverages the high capacity of SnO2 and the structural and mechanical stability MXene provides. The SnO2@MXene anode exhibits superior electrochemical performance, with a high specific capacity of 678 mAh g− 1 at a current rate of 2.0 A g− 1 over 500 cycles, outperforming pristine MXenes and SnO2 nanoparticles.

Microwave-Assisted Hydrothermal Synthesis of Photocatalytic Truncated-Bipyramidal TiO2/Ti3CN Heterostructures Derived from Ti3CN MXene.

TiO2/MXene heterostructure has garnered significant interest as a photocatalyst due to its large surface area and efficient charge carrier separation at the interface. However, current synthesis methods produce TiO2 without clear crystal faceting and often require complicated postprocessing step, limiting its practical applications. We demonstrate a facile and controlled microwave-assisted hydrothermal synthesis for transforming multilayered Ti3CN MXene to a truncated-bipyramidal TiO2/Ti3CN heterostructure. The resulting TiO2 nanocrystals at the Ti3CN surface exhibited crystalline anatase truncated bipyramids, exposing {001} and {101} facets. We further tailored an indirect optical band gap of the TiO2/Ti3CN heterostructure in the range of 3.17-3.23 eV by varying the hydrothermal synthesis time from 15 min to 5 h at a fixed temperature of 160 °C. Efficient charge separation allowed us to decompose 97% of methylene blue (MB) within 30 min of ultraviolet (UV) light irradiation, ∼3.9-fold faster than the benchmark P25, higher than any other TiO2/MXene heterostructures. With simulated white light, we achieved over 60% efficiency of the dye decomposition within 2 h of irradiation, which resulted in 1.5-fold faster kinetics than P25. We also observed a similar excellent performance of Ti3CN-derived TiO2 in decomposing various persistent synthetic dyes, including commercial textile dye, methyl orange, and rhodamine B. In conclusion, our study provides a strategy for utilizing MXene chemical reactivity to produce highly crystalline optically active TiO2/Ti3CN heterostructure. The developed heterostructure can serve as an efficient photocatalyst for the degradation of organic pollutants.

Ti3C2Tx/Ni0.2Mn0.4Zn0.4Fe2O4 ferrite nanocomposites: Dual-loss mechanism with engineered composition for microwave absorption

Ni0.2Mn0.4Zn0.4Fe2O4 (NMZF) nanoparticles were anchored on the surface of MXene(Ti3C2Tx) to form Ti3C2Tx/NMZF nanocomposites for optimization of microwave absorption performance. The Ti3C2Tx/NMZF nanocomposites were synthesized by using a four-step strategy, including sonication, stirring, hydrothermal reduction and vacuum drying. More than 40 percent of the NMZF nanoparticles in this nanocomposite were assembled to form a conductive network. Meanwhile, the multilayer MXene acted as a framework to host the NMZF nanoparticles, providing dipolar polarization, interfacial polarization and eddy current loss. Benefiting from the structure design of MXene, combined with magnetic materials and optimized impedance matching, the Ti3C2Tx/NMZF exhibited a minimum reflection loss (RLmin) of −57.39 dB, with a thickness of 2.97 mm and an effective absorption bandwidth (EAB) of 3.2 GHz. Therefore, such a facile method could be used to construct nanocomposites with microwave absorption performance (-57.39 dB, 3.2 GHz), so as to address microwave pollution issues.

Ammonia-assisted heterocyclic amine exerts soft delamination and interlayer engineering of Ti3C2Tx MXene for fabricating stable supercapacitors

The application of two-dimensional titanium carbide MXenes (Ti3C2Tx) for electrochemical energy storage and conversion has garnered considerable attention in recent years. For practical applications, gradual delamination, phase shift, and/or structural disintegration of MXene flakes in aqueous conditions are the challenges needed to be addressed. Herein, a unique and effective approach for in situ manipulation of MXene edge and surface by gentle delamination using 5-azaindole (5-Az; a heterocyclic amine) and ammonium hydroxide (NH4OH) has been developed. In the presence of NH4OH, 5-Az enables soft delamination of multilayer MXene without sonication, and more importantly, allows in situ functionalization of its surface and edges via a nucleophilic substitution reaction at the Ti-atom sites at room temperature. In addition, the easy intercalation of 5-Az in the multilayer MXene allows for an increase in its interlayer spacing when it is made into a film or electrode, which is beneficial for various electrochemical applications. The 5-Az functionalization provides exceptional stability of MXenes for up to 500 days in water at room temperature. The NH4OH-treated- and 5-Az-functionalized MXene (NH4OH-5-Az/Ti3C2Tx) shows increased interlayer spacing (1.67 nm) when compared to the MXene treated with NH4OH (NH4OH-Ti3C2Tx) (1.25 nm), enhanced ion- and charge-transport properties resulting in a remarkable specific capacitance of 631 F g–1 at 2 A g–1 with capacitance retention of 82 % after 150 days. Having high specific capacitance and excellent stability, the NH4OH-5-Az/Ti3C2Tx prepared through the proposed simple and effective approach holds great potential as high-performance electrodes for supercapacitors.

Confined interfacial self-assembly of graphene-like carbon/MXene composite electrodes for capacitive deionization

Electrodes that have high desalting capacity, fast desalting rates and stable desalination performance are needed in capacitive deionization (CDI) technologies for water security. Herein, confined interfacial self-assembly of lignin-based graphene-like carbon (GC) precursors in Ti3C2-MXene interlayers was developed for forming GC/MXene composites. The formation of GC was generated in-situ by KHCO3-assisted pyrolytic carbonization which leads to exfoliation of multilayered MXene thereby forming GC/MXene heterostructures having strong interfacial interactions. GC/MXene exhibited tremella-like nanosheets morphology, accompanied by the formation of a TiO2 phase at the interface of GC and MXene hybridization, which confirmed formation of a heterostructure. Crystallographic phase identification of GC/MXene showed the exfoliation of MXene. GC/MXene had an ultra-negative surface charge of −39.3 mV, making it favorable for application as a cathode for Na+ removal. The GC/MXene heterostructure had high desalting capacity (54.2 mg g−1), high desalting rate (2.7 mg g−1 min−1), and stable cycling performance (90 % SAC retention after 30 cycles). The interfacial self-assembly strategy developed in this work is expected to enable green synthesis routes for graphene/MXene-based composite materials that allow construction of 2D/2D heterostructures for multilayer MXene and their analogues.

Mechanisms of mercury removal from water with highly efficient MXene and silver-modified polyethyleneimine cryogel composite filters

Safeguarding aquatic ecosystems and human health requires effective methods for removing pollutants. Mercury (Hg) is a very toxic pollutant with a global presence and is highly mobile and persistent. Here, innovative materials were prepared for separating Hg(II) from water, and the mechanisms underlying the efficient uptake of Hg species have been investigated. The sorbents include silver (Ag) nanoparticles and multilayered Ti3C2Tx MXene, both incorporated into the structure of a three-dimensional polyethyleneimine porous cryogel (PEI) that acts as a scaffold holding and exposing nano active sites involved in the removal of Hg. Specifically, Ag particles were deposited onto MXene phases, and the resulting composite was embedded in the macroporous PEI polymer (PEI/MXene@Ag cryogel). The composite has beneficial properties regarding Hg removal: 99% of Hg was separated from waste within 24 h in batch studies. The maximum removal capacity of Hg reached 875 mg/g from HgCl2, and 761 mg/g and 1280 mg/g from Hg(OAc)2 and Hg(NO3)2 salts by PEI/MXene@Ag. The Hg uptake stems from the composite’s relatively large specific surface area, layered porous channels, and highly dispersed Ag nanoparticles in the multilayered Ti3C2Tx MXene. The matrix in the water samples that were treated with the composite did not hinder the uptake of Hg by PEI/MXene@Ag. The high effectiveness achieved for the removal of Hg, combined with rapid adsorption kinetics, high efficiency, and selectivity, positions it as an efficient solution. Future work should address upscaling its preparation for increasing readiness towards mitigating Hg in surface water.

Novel 2D heterostructure composites of V2C MXene/TiO2 and graphene/TiO2 for platinum replacement in dye-sensitized solar cells

This study evaluates the potential of V2C MXene/TiO2 and Graphene/TiO2 composites as alternatives to platinum for counter-electrodes in dye-sensitized solar cells (DSSCs). V2C MXene was synthesized by selectively etching the aluminum layer from V2AlC MAX phase powder, resulting in multilayered V2C MXene. The layered morphologies of MXene and graphene were confirmed via Scanning Electron Microscopy (SEM), while their crystalline structures were validated using X-ray diffraction (XRD) analysis. SEM analysis confirmed the delaminated layered structure of graphene and the distinct layers of V2C MXene. XRD findings showed that MXene has significantly greater interlayer spacing than graphene, offering more catalytic sites for charge injection. Electrocatalysts were prepared by incorporating TiO2 paste with MXene and graphene, with TiO2 serving as a binder. These composites were then employed as counter-electrode materials in dye-sensitized solar cells. The MXene-based counter electrode achieved a photoconversion efficiency of 1.625 %, surpassing graphene-based (1.149 %) and Pt-based (1.567 %) counterparts under standard illumination. The efficiency of cells was meticulously characterized over an extended period. The results indicated that the efficiency of these cells remained stable over time. This stability suggests that MXene/TiO2 and Graphene/TiO2 based catalysts are robust and do not degrade with time.

3D Printable Mxene for Chemoresistive Sensing

The demand for smaller microenvironments in modern electronics has prompted a search for new solutions, with the MXene (Mn+1XnTx) family emerging as a strong candidate due to its unique properties. This research focuses on incorporating microelectronics into micropatterned structures using cost-effective methods, opening up possibilities for smart devices and microsystems. The study details the synthesis and processing of titanium carbide (Ti3AlC2)-based MXene nanoparticles, with a novel in situ etching method to create multi-layered MXene (Ti3C2Tx) nanosheets. Water-based Ti3C2Tx inks in various concentrations were examined, and 3D printing was used to create micropatterned MXene layers with anisotropic electrical properties and energy storage potential, making them promising for 3D printable devices.

Dielectric and thermal conductive properties of differently structured Ti3C2Tx MXene-integrated nanofibrillated cellulose films

The fabrication of nanocellulose-based substrates with high dielectric permittivity and anisotropic thermal conductivity to replace synthetic thermoplastics in flexible organic electronics remains a big challenge. Herein, films were prepared from native (CNF) and carboxylated (TCNF) cellulose nanofibrils, with and without the addition of thermally conductive multi-layered Ti3C2Tx MXene, to examine the impact of polar (− OH, − COOH) surface groups on the film morphological, moisturizing, dielectric, and thermal dissipation properties. The electrostatic repulsion and hydrogen bonding interaction between the hydrophilic surface/terminal groups on CNF/TCNF and MXene was shown to render their self-assembly distribution and organization into morphologically differently structured films, and, consequently, different properties. The pristine CNF film achieved high intrinsic dielectric permittivity (ε' ~ 9), which was further increased to almost ε' ~ 14 by increasing (50 wt%) the MXene content. The well-packed and aligned structure of thinner TCNF films enables the tuning of both the composite’s dielectric permittivity (ε' ~ 6) and through-plane thermal conductivity (K ~ 2.9 W/mK), which increased strongly (ε' ~ 17) at higher MXene loading giving in-plane thermal conductivity of ~ 6.3 W/mK. The air-absorbed moisture ability of the films contributes to heat dissipation by releasing it. The dielectric losses remained below 0.1 in all the composite films, showing their potential for application in electronics.Graphic abstract

Synthesis of Ti1‐xWx Solid Solution MAX Phases and Derived MXenes for Sodium‐Ion Battery Anodes

AbstractA distinguishing feature of MAX phases and their MXene derivatives is their remarkable chemical diversity. This diversity, coupled with the 2D nature of MXenes, positions them as outstanding candidates for a wide range of electrochemical applications. Chemical disorder introduced by a solid solution can improve electrochemical behavior. Up to now, adding considerable amount of tungsten (W) in MAX phase and MXenes solid solutions, which can enhance electrochemical performance, proved challenging. In this study, the synthesis of M site Ti1‐xWx solid solution MAX phases are reported. The 211‐type (Ti1‐xWx)2AlC exhibits a disordered solid solution, whereas the 312‐type (Ti1‐xWx)3AlC2 displays a near‐ordered structure, resembling o‐MAX, with W atoms preferentially occupying the outer planes. Solid‐solution MXenes, Ti2.4W0.6C2Tz, and Ti1.6W0.4CTz, are synthesized via selective etching of high‐purity MAX powder precursors containing 20% W. These MXenes are evaluated as sodium‐ion battery anodes, with Ti1.6W0.4CTz showing exceptional capacity, outperforming existing multilayer MXene chemistries. This work not only demonstrates the successful integration of W in meaningful quantities into a double transition metal solid solution MAX phase, but also paves the way for the development of cost‐effective MXenes containing W. Such advancements significantly widen their application spectrum by fine‐tuning their physical, electronic, mechanical, electrochemical, and catalytic properties.

PMMA microspheres-embedded Ti3C2Tx MXene heterophotocatalysts synergistically working for multiple dye degradation

We developed a novel MXene/polymer hybrid material for enhanced photodegradation of multiple organic dyes. Specifically, uniform-sized PMMA microspheres and multilayer Ti3C2Tx MXene were integrated through a facile solution process to form PMMA/Ti3C2Tx composites. The hybridization of the two components significantly increased the specific surface area and pore volume. An optimized composite showed high photocatalytic activity, demonstrating 93 and 98 % degradation efficiencies for orange G (OG) and rhodamine B (RhB) in 60 min of light illumination. Furthermore, the composite revealed good recyclability without a significant performance drop even after four cycles. Moreover, the composite retained its high photocatalytic activity at various conditions, including elevated temperatures, a wide range of pH levels, and in tap water. These results manifest that the PMMA/Ti3C2Tx hetero-photocatalyst is well suited for use in wastewater treatment and environmental cleanup.