Two-dimensional MXene Research Articles

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.

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.

Research on the modification of magnesium hydride by two-dimensional layered Mo2Ti2C3 MXene

One of the most important technologies for the sustainable development of energy in the future is solid-state hydrogen storage. This study employed etching methods to fabricate two-dimensional layered catalyst Mo2Ti2C3 MXene, which was compared with unetched MAX phases Mo2Ti2AlC3 and Ti3C2, as well as Mo2C. Through mechanical ball milling, these materials were mixed with MgH2 to prepare composite materials, including MgH2 + Ti2C3, MgH2 + Mo2C, MgH2 + Mo2Ti2AlC3, and MgH2 + Mo2Ti2C3. According to the study, Mo2Ti2C3 demonstrates the synergistic catalytic actions of Ti and Mo in contrast to Ti2C3 and Mo2C. The composite material MgH2 + Mo2Ti2C3 lowers the initial dehydrogenation temperature of MgH2 to 180 °C, which is 165 °C lower than pure MgH2. After 30 min at 250 °C, the dehydrogenation amount is approximately 5.85 wt%. Hydrogen absorption begins at 40 °C and reaches approximately 5.75 wt% at 150 °C. Additionally, it maintains a reversible hydrogen storage capacity of up to 96 % even after 20th cycles at 300 °C. This is because Mo2Ti2C3 has one less layer of Al than Mo2Ti2AlC3, which results in a wider interlayer spacing, more active sites for MgH2, and facilitates hydrogen molecule dissociation and recombination.

Photoinduced Charge Transfer Empowers Ta4C3 and Nb4C3 MXenes with High SERS Performance.

This study introduces two-dimensional (2D) Ta4C3 and Nb4C3 MXenes as outstanding materials for surface-enhanced Raman scattering (SERS) sensing, marking a significant departure from traditional noble-metal substrates. These MXenes exhibit exceptional SERS capabilities, achieving enhancement factors around 105 and detection limits as low as 10-7 M for various analytes, including environmental pollutants and drugs. The core of their SERS functionality is attributed to the robust interfacial photoinduced charge-transfer interactions between the MXenes and the adsorbed molecules. This deep insight not only advances our understanding of MXene materials in SERS applications but also opens new avenues for developing highly sensitive and selective SERS sensors. The potential of Ta4C3 and Nb4C3 MXenes to revolutionize SERS technology underscores their importance in environmental monitoring, food safety, and beyond.

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.

Synergic effect between La-MOF and MXene: Revolutionizing TPU with improved mechanical strength and fire safety

Two-dimensional MXene nanosheets with lamellar structure and high specific surface area are considered promising flame retardants for polymers. However, MXene easily accumulates in polymer materials, resulting in the impairment of their mechanical properties. Metal-organic frameworks (MOFs) not only address this issue effectively but also improve compatibility with polymer materials due to their organic components. In this work, lanthanide rare-earth MOF (La-MOF) were successfully grown in-situ on the MXene surface to prepare hybrid flame retardants (La-MOF@MXene), then added to thermoplastic polyurethane (TPU). The La-MOF suppressed the accumulation of MXene in TPU, and the synergistic effect between them improved the fire safety and mechanical strength of TPU composites. The peak heat release rate of the TPU composites with the addition of 3 wt% La-MOF@MXene was 473.3 kW/m2, which represented a 49.4 % decrease compared to that of pure TPU. Besides, due to the synergic properties of MXene and La-MOF, La-MOF@MXene further reduced total smoke, CO2, and CO of TPU composites in fires. Moreover, with the addition of 3.0 wt% La-MOF@MXene, the tensile strength and elongation at break of TPU composites dramatically improved to 42.4 MPa and 686 %, respectively. Therefore, this study provides a novel paradigm for preparing hybrid flame retardants that can improve the fire safety and mechanical properties of TPU composites, exhibiting broad application prospects.

Plasmonic molybdenum carbide MXene nanosheets for highly efficient and stable perovskite solar cells

Besides the excellent metallic electrical conductivity, high carrier mobility, and high optical transmittance, the two-dimensional MXenes exhibiting impressive optical and plasmonic properties have been explored to photodiodes. However, their potential use of surface plasmons oscillating in perovskite solar cells has not been studied. Herein, we incorporate, for the first time, Mo2CTx MXene nanosheets with characteristic plasmonic absorption in the whole visible region into the perovskite active layer. First, the presence of Mo2CTx nanosheets in the perovskite film increases the perovskite grain size due to the decreased growth rate and passivation of the defects around the grain boundaries through strong interaction with undercoordinated Pb2+. Furthermore, with the help of the localized surface plasmon resonance effect of Mo2CTx nanosheets, the exciton binding energy in the perovskite absorber is reduced, which suggests the efficient exciton dissociation and enhanced charge separation. Consequently, Mo2CTx nanosheets based perovskite solar cell device exhibits a champion power conversion efficiency (PCE) of 24.05 %. It is worth noting that the unencapsulated devices demonstrate considerably improved stability, maintaining about 89.25 % of the initial PCE after aging in air for 3000 h. This fascinating strategy provides more opportunities of the functional MXene materials for the perovskite optoelectronics.

Enhancement of Electron Transport Characteristics Using MXene-MnFeO3 Nanocomposite Integration with Fullerene Derivatives for the Perovskite-Based Solar Cells and Detectors.

In this study, we prepared a hybrid film incorporating the MnFeO3-decorated conducting two-dimensional (2D) MXene sheet-suspended [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) electron transfer layer (ETL) for the perovskite solar cells (PSCs) and detectors. The incorporation of MXene-MnFeO3 with the PCBM ETL could drive exceptional conducting features for the PSCs. Moreover, the presence of MXene-MnFeO3 facilitated superior charge transfer pathways, thereby enhancing the electron extraction and collection processes. This enhancement was directed to improve the electron mobility within the device, resulting in high photocurrents. The designed interface engineering with the MXene-MnFeO3 nanocomposite-tuned PCBM ETL has produced a remarkable power conversion efficiency of 17.79% ± 0.27. Moreover, X-ray detectors employing PCBM modulated with the MXene-MnFeO3 ETL achieved notable performance metrics including 18.47 μA/cm2 CCD-DCD, 5.53 mA/Gy·cm2 sensitivity, 7.64 × 10-4 cm2/V·s electron mobility, and 1.51 × 1015 cm2/V·s trap density.

Surface Termination (-O, -F or -OH) and Metal Doping on the HER Activity of Mo2CTx MXene.

Two-dimensional MXenes have recently garnered significant attention as electrocatalytic materials for hydrogen evolution reaction (HER). However, previous theoretical studies mainly focused on the effect of pure functional groups while neglecting hybrid functional groups that are commonly observed in experiments. Herein, we investigated the hybrid functionalized Mo2CTx MXene (T=-O, -F or -OH) to probe the HER properties. In binary O/F co-functionalization, the presence of F groups would attenuate the H adsorption and lead to the enhanced HER activity than the fully O-terminated Mo2CO2. However, the surface HER activity of ternary O/F/OH functionalized Mo2CTx is not satisfactory owing to the relatively weak H adsorption capacity. To further enhance the catalytic activity, modification was performed by introducing another metal element into its lattice structure. The doped metal (Fe, Co, Ni, Cu) exhibits reduced charge transfer to O compared to Mo atoms, leading to enhanced H adsorption and improved overall activity. The synergistic effect of hybrid functionalization and TM modification provides useful guidance for achieving feasible Mo2CTx candidates with high HER performance, which can be applied to the electrocatalytic applications of other MXenes.

Novel sensitive electrochemical detection of paracetamol using magnetite/MXene electrode by differential pulse voltammetry

In this research work, a novel electrochemical sensor-based Fe3O4/Ti3C2 MXene @ glassy carbon electrode (GCE) for the detection of paracetamol was prepared by simple ultrasonic method by combining Ti3C2 MXene and Fe3O4 nanoparticles. The Fe3O4/Ti3C2 MXene nanomaterial was characterized by the means of different techniques: X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM), nitrogen adsorption/desorption isotherms, as well as Fourier transform infrared spectroscopy (FTIR). The characterization results revealed the homogenous distribution of the prepared cubic Fe3O4 NPs within the prepared two-dimensional layered Ti3C2 MXene. The Fe3O4/Ti3C2 MXene @ GCE was used for the sensitive determination of the well-known analgesic drug paracetamol by differential pulse voltammetry (DPV). The prepared Fe3O4/Ti3C2 MXene @ GCE was characterized electrochemically, and the results showed that Fe3O4/Ti3C2 MXene @ GCE is a potential working electrode for the sensitive detection of paracetamol with very low detection limit (0.63 nM), within a linear dynamic range of 0.0–110.0 µM, high reproducibility and repeatability; with a very low relative standard deviation (SD%) for 7 days measurement (3.07–3.42 %), accuracy with a SD% of 0.89, high precision of 99.48 % in distilled water and 98.51 % in sea water. The proposed electroanalytical method was applied for the detection and quantification of paracetamol in real water samples, as well as different analgesic medical formulations, and the results showed outstanding accuracy and precision indicating the suitability of the Fe3O4/Ti3C2 MXene @ GCE electrode for the sensitive, accurate determination of paracetamol in diferrent matrices.

Realization of hydrogenation-induced superconductivity in two-dimensional Ti2N MXene.

Two-dimensional (2D) MXene superconductors have been currently attracting considerable interest due to their unique electronic properties and diverse applicability. Utilizing first-principles computational methods, we have designed two distinct configurations of hydrogenated 2D Ti2N MXene materials, namely Ti2NH2 and Ti2NH4, and have conducted an exhaustive analysis of their structural stability, electronic characteristics, and superconductivity. Hydrogenation endows monolayer Ti2N with inherent metallic characteristics, as evidenced by an elevated density of states (DOS) at the Fermi level (Ef). Notably, Ti2NH4 exhibits a superconducting critical temperature (Tc) of 15.8 K, which is predominantly ascribed to the electronic contributions stemming from the Ti 3d orbitals. Analysis of phonon dispersion underscores the pivotal role that diverse lattice vibrational modes play in electron-phonon coupling (EPC), particularly the significance of low-frequency vibrations for facilitating electron pairing and the emergence of superconductivity. Furthermore, strain engineering can effectively modulate the superconducting properties of Ti2NH4, with a 2% tensile strain enhancing the EPC strength (λ) to 0.857 and increasing Tc to 18.7 K. This research elucidates the superconducting mechanisms of hydrogenated Ti2N structures, offering valuable insights for the development of novel 2D superconducting materials.

Fabrication of MXene-encapsulated Co@C nanoparticles for efficient microwave absorption in the X-band

Two-dimensional MXene has structural advantages in electromagnetic wave scattering due to its layered structure, but MXene materials can lead to impedance mismatch problems due to their high dielectric constants, so it is still a challenge to design highly efficient wave-absorbing materials based on MXene with low reflection loss, thin thickness, and wide absorption frequency. In this study, composite wave-absorbing materials were fabricated from Co–Co PBA precursors and MXene using liquid nitrogen flash freezing and freeze-drying techniques. By treating MXene and the PBA precursor at a high temperature of 750 °C, a rich heterogeneous interface was formed between Co@C and MXene (CCM7), and the impedance matching was optimized to improve the reflection loss capability. The optimized sample has an effective absorption bandwidth of 4.1 GHz at 2.5 mm covering the entire X-band with a minimum reflection loss of −61.42 dB. It is also demonstrated that CCM7 is satisfactory for Radar Cross-Section of flat panels and unmanned aerial vehicles by CST calculations, and this work provides a fresh perspective on the use of effective MXene composites for microwave absorption.

Insights into performance and mechanism of CuCo2O4/MXene composite as an efficient peroxymonosulfate activator for p-nitrophenol degradation

The slow redox cycle during oxidation and the toxicity risk due to leaching of metal ions greatly hinder the practical application of transition metal-based catalysts in advanced oxidation processes. In this study, a novel layered-structured CuCo2O4/MXene composite was prepared by self-assembling CuCo2O4 spinel with two-dimensional MXene and used as a heterogeneous catalyst based on peroxymonosulfate (PMS) activation for the oxidative degradation of p-nitrophenol (4-NP). Benefiting from its unique structure, the degradation efficiency of 4-NP by CuCo2O4/MXene-activated PMS was close to 100 % within 10 min at the initial pH 7.0. Quenching experiments and electron paramagnetic resonance demonstrated that both radical (SO4•- and •OH) and non-radical (1O2) pathways were involved in the degradation of 4-NP. X-ray photoelectron spectroscopy analysis showed that the introduction of MXene could significantly promote the efficient redox cycling of Cu2+/Cu+ and Co3+/Co2+ on the catalyst surface, thus providing a continuous driving force for the PMS activation. More importantly, CuCo2O4/MXene exhibited good ionic interference resistance, high stability and low metal ion leaching rate, suggesting its potential practical application. This work not only demonstrates that CuCo2O4/MXene is a promising catalyst for the degradation of organic pollutants by PMS activation, but also provides a new idea for the development of efficient PMS-activated catalysts for pollutant degradation.

Cu[formula omitted]Se/MXene (Ti[formula omitted]C[formula omitted]T[formula omitted]) composite achieved ultra-low thermal conductivity and enhanced thermoelectric performance

Due to the significant mismatch in phonon density of states between carbon (C) and Cu2Se, the thermal conductivity of Cu2Se can be notably enhanced by incorporating low-dimensional carbon-based materials. This study propose an innovative approach where two-dimensional MXene material Ti3C2Tx is introduced into Cu2Se, creating numerous Cu2Se/MXene heterogeneous interfaces within the matrix. These interfaces induce high-density dislocations, which enhance multi-scale phonon scattering efficiency. Consequently, they significantly reduce lattice thermal conductivity across the entire temperature range tested. Additionally, the heterogeneous interfaces facilitate energy filtration, selectively filtering out low-energy carriers and thereby optimizing the high intrinsic carrier concentration of Cu2Se to a certain extent. Finally, the total thermal conductivity of the Cu2Se/0.4 wt% Ti3C2Tx sample at 795 K is markedly lower at 0.27 Wm−1K−1 compared to the average level of Cu2Se materials. As a result, the ZTmax reaches 2.11, reflecting a 109% enhancement compared to pristine Cu2Se.