MXene Layers Research Articles

Synthesis, Properties, and Applications of Nanocomposite Materials Based on Bacterial Cellulose and MXene.

MXene exhibits impressive characteristics, including flexibility, mechanical robustness, the capacity to cleanse liquids like water through MXene membranes, water-attracting nature, and effectiveness against bacteria. Additionally, bacterial cellulose (BC) exhibits remarkable qualities, including mechanical strength, water absorption, porosity, and biodegradability. The central hypothesis posits that the incorporation of both MXene and bacterial cellulose into the material will result in a remarkable synthesis of the attributes inherent to MXene and BC. In layered MXene/BC coatings, the presence of BC serves to separate the MXene layers and enhance the material's integrity through hydrogen bond interactions. This interaction contributes to achieving a high mechanical strength of this film. Introducing cellulose into one layer of multilayer MXene can increase the interlayer space and more efficient use of MXene. Composite materials utilizing MXene and BC have gained significant traction in sensor electronics due to the heightened sensitivity exhibited by these sensors compared to usual ones. Hydrogel wound healing bandages are also fabricated using composite materials based on MXene/BC. It is worth mentioning that MXene/BC composites are used to store energy in supercapacitors. And finally, MXene/BC-based composites have demonstrated high electromagnetic interference (EMI) shielding efficiency.

Pillaring Behavior of Organic Molecules on MXene: Insights from Molecular Dynamics Simulations.

Pillaring MXene with organic molecules is an effective approach to expand the interlayer spacing and increase the accessible surface area for enhanced performance in energy storage applications. Herein, molecular dynamics simulations are employed to explore the pillaring effect of six organic molecules on Ti3C2O2. The interlayer spacing and structural characteristics of MXene after the insertion of different organic molecules are examined, and the influence of the type and quantity of organic molecules on the pillared MXene structure is systematically investigated. The results demonstrate that the inserted molecules are influenced by interactions between MXene layers, resulting in a thinner morphology. Effective pillar support on MXene is achieved only when a specific quantity of organic molecules is inserted between the layers. Furthermore, different organic molecules occupy distinct surface areas on MXene when acting as pillars. Pillaring molecules with a Pi-conjugated ring structure require a larger surface area on MXene, whereas those with a branched structure occupy a smaller surface area. Additionally, organic molecules containing oxygen functional groups tend to aggregate due to hydrogen bonding, impeding their diffusion within MXene sheets. Considering the interlayer expansion of MXene, surface area occupation, and diffusion characteristics, the isopropylamine demonstrates the most favorable pillaring effect on MXene. These findings provide valuable insights into the design and application of pillared MXenes in energy storage and other applications. Further studies on the properties and applications of the optimized pillared MXene structures will be conducted in the future.

Long‐Term Infrared Stealth by Sandwich‐Like Phase‐Change Composites at Elevated Temperatures via Synergistic Emissivity and Thermal Regulation

AbstractThe rapid development of infrared surveillance technologies has attracted great attention for scientists to design advanced functional materials with prominent infrared stealth and thermal camouflage effectiveness. In the current study, a sandwich‐like functional composite based on a crosslinked polyimide aerogel, a meso‐erythritol (mE)‐based phase‐change composite, and an MXene film has been developed to achieve long‐term thermal camouflage at elevated temperatures. In this composite system, the lower aerogel layer can act as a barrier to insulate heat transfer through its layer‐stacking structure under ultralow directional thermal conduction. The introduction of the middle phase‐change composite layer ensures that the composite system obtains a dynamical temperature‐regulation capability through sensible and latent heat absorption of mE as a phase change material, while the upper MXene layer provides a very low emissivity surface for the system. As a result, the developed composite achieves a significant reduction in the thermal radiation temperature of a high‐temperature target. Moreover, the MXene film exhibits good electromagnetic interference shielding effectiveness, making the sandwich‐like composite obtain a thermal camouflage capability in various complicated scenarios. This work provides a promising approach for the design of advanced functional materials to realize long‐term infrared stealth and thermal camouflage of high‐temperature targets in security protection and counter‐surveillance.

Recent advances in synthesis of MXene-based electrodes for flexible all-solid-state supercapacitors

Various energy storage sources have been developed so far, among which supercapacitors are more important for the forthcoming generations due to their small size and portability. Supercapacitors as good alternatives to batteries have recently attracted more attention because they have higher power and excellent charging-discharging rate which is considered as a challenging issue that limits the use of batteries. Supercapacitors also have other advantages over batteries, including higher reversibility and cycle life, lower maintenance costs, and safer electrode materials. MXenes have emerged as a new class of 2D composites in electrode materials for supercapacitors as low-cost and environment-friendly carbides and nitrides. MXenes are suitable inorganic compounds with excellent electrochemical properties and mechanical integrity to improve supercapacitor energy density at a new interval. This review presents new synthesis strategies to prevent the self-accumulation of MXene layers. First, the fundamental working theories of different supercapacitors are outlined. Next, an overview of the electrode material based on MXenes is outlined, and the latest solutions for increasing the active sites and improving the ion transfer rate have been collected. Hybridization and doping of MXenes change the properties of the composite, leading to a transformation in the structure and an increase in the capacitance. Furthermore, the utilization of double-transition metal MXenes solves challenges such as structural destruction and short life spans in multiple charge-discharge cycles. Then evaluation of the new MXene-based electrode materials in all-solid-state supercapacitors has been summarized. Finally, an overview of the latest developments in the creation of all-solid-state flexible supercapacitors as well as our predictions for future lines of inquiry is provided.

Detection of chlorpyrifos via carbon nanotubes and AuPd nanoparticles-enhanced MXene electrode-based acetylcholinesterase biosensor

An ultra-sensitive and high-efficient acetylcholinesterase (AChE) electrochemical sensing platform on the basis of MXene/carbon nanotubes (CNTs) and Au-Pd composites was constructed for the rapid detection of chlorpyrifos. Negative CNTs modified with cationic surfactant cetyltrimethylammonium bromide were self-assembled on MXene through the electrostatic interaction. The introduction of CNTs and AuPd nanoparticles reduced the stacking of MXene layers and increased the utilization of specific surface area to load AChE. The MXene/CNTs/AuPd-based glassy carbon electrode (GCE) exhibited relatively lower electrochemical impedance compared with other materials. The prepared MXene/CNTs/AuPd-AChE/GCE-based electrochemical method possessed high repeatability, reproducibility, and anti-interference ability. The linear range for detecting chlorpyrifos was 2.85 × 10−12–2.85 × 10−6 M and the limit of detection was 1.98 pM. Finally, the established method was successfully used to detect chlorpyrifos in spinach and orange and recoveries were ranging from 93.68 % to 104.21 %, which presented the great potential for quantitatively analyzing of organophosphorus pesticides in food samples.

Stable N-doped Ti3C2Tx gas sensors for recoverable detection of ammonia at room temperature

Herein, highly recoverable, and stable, nitrogen-doped Ti3C2Tx-based sensors are developed for ammonia detection at room-temperature. Ti3C2Tx MXene as a room-temperature gas sensor has two main drawbacks: weak recovery and resistance drift. In this work; Ti3C2Tx nano-sheets were derived from the pre-synthesized Ti3AlC2 by selective aluminum etching using HF acid. The sensors fabricated using pristine Ti3C2Tx had high response toward polar gases, particularly ammonia. The sensors’ response to 100 ppm ammonia was 10%. However, they experienced incomplete recovery and baseline resistance drift. To overcome these problems, we introduced a novel method, in which, before fabricating the gas sensors, the surface of synthesized Ti3C2Tx MXene was modified by a nitrogen treatment strategy. In this method, the MXene layers were doped with nitrogen using NH3 gas at 500 °C for 2 h. In nitrogen-doped Ti3C2Tx-based sensors, both recovery and drift problems disappeared. The response of the nitrogen-doped Ti3C2Tx is 3.7% toward 100 ppm ammonia, which is a notable response for a stable, recoverable, room-temperature gas sensor.

Expanded interlayer spacing of SnO2 QDs-Decorated MXene for highly selective luteolin detection with Ultra-Low limit of detection

Although there have been advancements in electrochemical catalysts for luteolin detection, their practical use is constrained by low sensitivity, inadequate selectivity, and unsatisfactory limit of detection. MXene, a class of 2D materials, possesses exceptional physical–chemical properties that make it highly suitable for electrochemical detection. Nevertheless, the self-stacking and limited interlayer spacing of MXene impede its extensive application in electrochemical detection. Herein, a SnO2 QDs-MXene composite is synthesized for selective electrochemical detection of luteolin. Inserting SnO2 QDs between tightly stacked MXene layers expands the d-spacing of MXene, enhancing the specific surface area and enabling abundant active sites for redox reactions. The inclusion of MXene in the modified SnO2 QDs-MXene/GCE electrode significantly enhances electron transfer. As a result, the electrode demonstrates exceptional luteolin detection capabilities, including a wide linear range (0.1–1200 nM), high sensitivity (12.4 μA μM−1), and an ultra-low limit of detection (0.14 nM). Additionally, the SnO2 QDs-MXene/GCE electrode exhibits good repeatability, excellent reproducibility, remarkable stability, and high selectivity, making it suitable for practical sample analysis. This research contributes to advancing ultra-low limit of detection sensors for accurate luteolin detection.

Charge storage improvement in uniformly grown TiO2 on Ti3C2Tx MXene surface

The energy storage capacity of MXenes can be significantly augmented by increasing their specific surface area, which can additionally amplify the number of active sites available for electrochemical reactions. Herein, we have presented a method to enhance the energy storage capacity of Ti3C2Tx MXenes by growing the TiO2 nanogrooves on the surface of Ti3C2Tx (termed as Ti3C2Tx-NG) without drying the exfoliated MXene layers using hydrothermal treatment. The Ti3C2Tx MXene flakes dimensions ranged from 500 to 1000 nm, whereas the decorated TiO2 nanogrooves have a size of ∼10 nm. The Ti3C2Tx MXene demonstrates a specific surface area (SSA) of ∼ 11 m2/g, while the Ti3C2Tx-NG exhibits an enhanced SSA of ∼40 m2/g. The Ti3C2Tx-NG utilized in the fabrication of symmetric supercapacitors exhibited a significantly higher specific capacitance (∼81 F/g) compared to Ti3C2Tx MXene (∼62 F/s) at a scan rate of 100 mV/s. Reversible oxidation and reduction reactions between TiO2 and Ti3C2Tx, accompanied by the adsorption or release of hydroxide ions (OH-) contribute to charge transport in the supercapacitors. Additionally, due to the layered structure of Ti3C2Tx MXene, a smaller number of ions can exist between two adjacent MXene layers due to the small spacing, whereas more ions can exist between two adjacent Ti3C2Tx-NG layers as interlayer spacing between adjacent layers is relatively broader due to the nanosized TiO2 nanogrooves, facilitating in the higher charge storage.

A strategy to boost the electrochemical properties of Ag–Fe2O3 with intercalation of MXene hydrogel

Due to the presence of several oxidation states, MXenes and their composites with different metal oxides are of significant interest for use in electrochemical energy storage devices. However, the restacking of MXene layers and weak electrical conductivity of metal oxides pose significant obstacles to their efficient electrochemical transport. To address these crucial problems, we synthesized MXene hydrogel-based composite nanomaterials. MXene stability can be significantly improved by incorporating MXene into hydrogels. MXene hydrogels have high mechanical strength, large surface areas, high electrical conductivity, high flexibility, and superb water absorbency. To effectively stop restacking and expand the surface area of the supercapacitor electrode material, a nanocomposite containing Fe2O3 nanospheres doped with silver and then entangled with cellulose-based MXene hydrogel was fabricated by a facile coprecipitation and ultrasonication procedure. The prepared nanomaterials were characterized for structural analysis via X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Electrochemical measurements were investigated in a 1 M aqueous solution of KOH, used as an electrolyte, via cyclic voltammetry, electrochemical impedance spectroscopy, and cyclic charge-discharge. It was observed that the MXene hydrogel boosted the electrochemical characteristics of the Fe2O3 nanospheres. The fabricated nanocomposite electrode exhibited an increase in specific capacitance. The obtained specific capacitance of the nanocomposite electrode was 709.4 Fg-1 (at 1 Ag-1) and exhibited capacitance retention of 84.4%. The research results revealed that the Ag–Fe2O3/MXene hydrogel nanocomposite has potential uses in energy storage devices.

Multifunctional Flexible MXene/AgNW Composite Thin Film with Ultrahigh Conductivity Enabled by a Sandwich-Structured Assembly Strategy.

Flexible composite films have attracted considerable attention due to great potential for healthcare, telecommunication, and aerospace. However, it is still challenging to achieve high conductivity and multifunctional integration, mainly due to poorly designed composite structures of these films. Herein, a novel sandwich-structured assembly strategy is proposed to fabricate flexible composite thin films made of Ag nanowire (AgNW) core and MXene layers by combination of spray coating and vacuum filtration process. In this case, ultrathin MXene layers play crucial roles in constructing compact composite structures strongly anchored to substrate with extensive hydrogen-bonding interactions. The resultant sandwich-structured MXene/AgNW composite thin films (SMAFs) exhibit ultrahigh electrical conductivity (up to 27193 S cm-1 ), resulting in exceptional electromagnetic interference shielding effectiveness of 16223.3 dB cm2 g-1 and impressive Joule heating performance with rapid heating rate of 10.4°C s-1 . Moreover, the uniform SMAFs can also be facilely cut into kirigami-patterned interconnects, which indicate superior strain-insensitive conductance even after long-term exposure to extreme temperatures. The demonstrated strategy offers a significant paradigm to construct multifunctional composite thin films for next-generation integrated flexible electronics with practical applications.

High-strength nacre-like composite films based on pre-polymerised polydopamine and polyethyleneimine cross-linked MXene layers via multi-bonding interactions

Demands for high-strength flexible electrodes have significantly increased across various fields, especially in wearable electronics. Inspired by the strong integrated layered structure of the natural nacre via multi-bonding interactions, we report the fabrication of the strong integrated nacre-like composite films based on pre-polymerised polydopamine and polyethyleneimine cross-linked MXene layers (p-DEM), achieving the synergic effect of hydrogen bonding, covalent bonding and electrostatic interactions. As a result, a high-level tensile strength of ∼302 MPa, 10.8 times higher than that of the plain MXene film, is obtained for the prepared p-DE0.5M composite film. Meanwhile, the composite film also delivers superior energy storage (∼1218F cm−3 at 5 mV s−1) and rate performances (capacitance retention of 81.3% at 1000 mV s−1). To demonstrate the practical application of the composite films, a symmetrical supercapacitor based on p-DE0.5M electrodes is assembled, which shows stable energy storage performances under different deformation states such as bending angles at 0, 60, 90 and 180°, or withstand repeated bending times (1000 cycles). This type of multi-bonding interactions induced strong integrated MXene assembly may promote the wide applications of MXene-based films in flexible electronics, artificial intelligence, and tissue engineering, to name a few.

Click-chemistry synergic MXene-functionalized flexible skeleton membranes for accurate recognition and separation

Membrane-based technology with accurate-recognition and specific-transmission has been regarded as one of the most promising strategies in environmental protection and energy conservation. However, membrane technique still faces challenges of “trade-off effect” between high selectivity and permeation flux within organic-aqueous mixed matrix. Here, well-intergrown click-chemistry synergic MXene-functionalized flexible skeleton membranes has been prepared in this strategy, enabling size-exclusion&structure selectivity by uniform location array imprinting unit and transport performance towards specific medicinal molecules of artemisinin (Ars). The well-assembled ultrathin cascade-type MXene layer guarantees the narrow interlayer nanochannels and the flexible skeleton modified mesoporous SiO2 nanoparticles provide active reaction platform for the construction of selective recognition space. The resulting membranes demonstrated outstanding selective separation performance with permeability factor that artesunate (Aru) /Ars and dihydro-artemisinin (d-Ars) / Ars of 3.17 and 2.89 and permeation flux of 1173.25 L·m−2·h−1·bar−1. Besides, combined with antibacterial durability, recycling performance, high separation performance in mobile phase stability of CMFMs, it is anticipated that this work hopefully opens a new avenue for efficient chiral separation to medicinal molecules, exhibiting broad potential for practical application.

Preparation of larger MXene layers and research progress in the field of gas adsorption and separation

Recently, MXene, a novel two-dimensional (2D) material, shows promising potential in many fields. Among these fields, gas separation and adsorption have emerged as new application areas for MXene. The number of studies relevant to the application of MXene in gas separation and adsorption is gradually increasing, making it a hot spot in scientific research. Therefore, timely and systematic reviews of the strengths and weaknesses of MXene are crucial to its further development. This article focused on the application of MXene in gas separation and adsorption. In this review paper, we presented some preparation methods of large MXene layers and practicable strategies for utilizing them to enhance the operational stability of MXene membranes, and the latest research advancements in the application of MXene in gas separation and adsorption. In terms of gas separation, we provided a systematic summary of the research progress based on the techniques used to prepare MXene membranes. As for gas adsorption, we discussed the research progress from both experimental and theoretical perspectives. This discussion was divided into three parts: (1) exploration of the impact of the surface groups on gas adsorption process; (2) analysis on the effect of gas adsorption in gas sensing; and (3) study on theoretical calculation pertaining to gas adsorption and separation. Finally, we evaluated the advantages and disadvantages of using MXene in gas separation and adsorption and then outlined the potential avenues for the future development of MXene. It is expected that this review may provide valuable insights and guidance for the researchers engaged in promoting the intensive study and the broad application of MXene.

3D Architectural MXene‐based Composite Films for Stealth Terahertz Electromagnetic Interference Shielding Performance

AbstractThe terahertz frequency range is gaining popularity in security, stealth technology, and the future 6G network communication. For the control of severe terahertz electromagnetic interference (EMI) pollution, frequency‐selective stealth‐capable shielding materials are being explored to mask terahertz signals. For the realization of masking terahertz signals, the robustness, lightweight, and shape‐conformable materials with excellent terahertz EMI shielding/absorption are crucial. Here, the study reports the fabrication of 3D symmetric pyramidal architectural MXene composite films with frequency‐selective stealth performance characteristics via the facile drop casting method. With the high absorption capability of 2D MXene layers, the MXene composite films exhibit substantial terahertz stealth performance. 3D pyramidal microstructure design leads to frequency selective surface‐assisted reflection resonance in the frequency range of 0.6–1.1 THz. The MXene composite film demonstrates an outstanding maximum terahertz shielding effectiveness (SE) of up to 70.4 dB and a specific SE of 0.55 dB µm−1. These terahertz SE values exceed all of those for MX‐based shielding material designs reported in the literature. The investigation will open a new direction toward developing terahertz EMI shielding thin films with easy integration into any surface for stealth capabilities.

(Invited) A Doped Mxene Dual Layer for Reliable Lithium Metal Anode

To meet the rapidly growing market in electrical vehicles (EVs) and portable electronic devices, a battery with high energy density is required. In order to reach this goal, Li metal, is considered as the most promising candidate as anode. However, the dendrite forming, low Coulombic efficiency (CE), and unstable solid electrolyte interphase (SEI) pose big challenges in applying Li metal in batteries. Here we introduce a dual-layer coated Li metal surface, which consists a lithium carboxylate organic layer and a doped MXene layer. The porous organic layer increases the wetting of electrolyte and forms a thin solid electrolyte interface (SEI). While the doped MXene leads to about 50% reduced thickness of inorganic-rich components among the SEI layer. A low overpotential of less than 30 mV over 1000 h cycling in symmetric cells was received. The functional groups along with the good electronic conductivity and smooth surface of the MXene greatly reduce the lithium plating/stripping energy barrier, enabling a dendrite-free lithium metal anode. The battery paired with NMC811 exhibited a high initial CE of 82.1%. A high capacity-retention of 175.4 mAh/g at 1.0 C was achieved after 350 cycles. After long 500 cycles, a reliable capacity was still remained while the cell with un-modified Li metal quickly dropped to below 74.2 mAh/g. In a 475 mAh pouch cell, the battery still exhibited a high discharge capacity of 165.6 mAh/g with a capacity retention of 90.2% after 200 cycles, while the cell with pure Li metal decreased to 80.5%. Keywords: Lithium metal; Battery; Anode; MXene; Doping

Aramid nanofiber-reinforced MXene/PEDOT:PSS hybrid fibers for high-performance fiber-shaped supercapacitors

In recent years, a great deal attention has been paid to one-dimensional fiber-shaped wearable energy storage devices, but further exploration is still needed to obtain fiber-shaped devices with high mechanical and electrochemical performance to meet the requirements of stretching, twisting and squeezing deformation in daily use. Herein, high-performance aramid nanofiber-reinforced (ANF) MXene/PEDOT:PSS hybrid fibers were fabricated by a simple and tractable wet spinning strategy. In this strategy, ANF played the role of fiber reinforcement and barrier for the MXene layer, not only greatly enhancing the mechanical properties of fibers, but also effectively preventing the re-stacking of MXene layers. As a kind of spinnable conductive polymer, PEDOT:PSS can effectively improve the spinnability of fibers. The obtained hybrid fiber exhibited high tensile strength and high conductivity. Meanwhile, the assembled all solid-state fiber-shaped supercapacitor (FSC) showed a high energy density of 9.8 mWh cm−3 at the power density of 250.7 mW cm−3. Besides, the assembled FSC displayed outstanding cycle performance (86.9% capacitance retention after 10 000 cycles) and excellent flexibility. It is worth noting that the FSC could be extended in series to meet the needs of different equipment. This work provides a good reference for the manufacture of wearable high-performance fiber-shaped devices by facile wet spinning.

A La2O3/MXene composite electrode for supercapacitors with improved capacitance and cycling performance

ABSTRACT Developing efficient electrode materials is a key towards high power electrochemical energy storage devices. Two-dimensional (2D) MXene shows excellent conductivity and electrochemical performance among other materials. However, the restacking of MXene layers may degrade their specific capacity and cycling performance. Considering this challenge, here we have designed a composite made of 2D MXene nanosheets and lanthanum oxide (La2O3) nanoparticles to overcome the limitations. The bifunctionality of La2O3 nanoparticles prevents the restacking of MXene layers and enhances the electrochemical properties of the electrode due to its good Faradic characteristics. The specific capacitance of the La2O3/MXene composite electrode is 366 F/g at 1 A/g, which is 4.5 and 3 times higher than those of the individual La2O3 and MXene. The composite electrode displays a capacitance retention of 96% after 1,000 cycles, which is due to synergistic effects between the two components and indicates the potential of La2O3/MXene composite for supercapacitors.

Crystal structure engineering of GdFeO3/Mxene composites with excellent electromagnetic wave absorption: Role of phase transition and high polarizability

The development of new materials capable of absorbing electromagnetic waves (EMA) is crucial to address issues like signal interference and crosstalk. In this study, we synthesized a novel composite material by combining MXene with GdFeO3 nanoparticles, employing crystal structure engineering to enhance electromagnetic wave attenuation between 2 and 18 GHz. The GdFeO3 (GFO) nanoparticles, sized at 30–40 nm, were evenly dispersed on the MXene layers' surface. Analysis of the composite material through XRD and Raman spectra revealed different phases of GdFeO3, exhibiting distinct crystal symmetries and coordination states. XPS and EPR measurements indicated the coexistence of various valence states of Fe, leading to oxygen vacancies within the lattice. By incorporating MXene, the composite material's specific surface area, and dielectric properties were significantly increased. The improved polarization and phase transition behavior resulted in a remarkable enhancement of the P-E loop, DM constant, and attenuation constant. The combination of the high-quality ferroelectric GdFeO3 and the disordered crystal phase within the multilayered MXene matrix led to enhanced conductive and magnetic losses. Experimental results demonstrated that the Pbnm GdFeO3/MXene composites displayed outstanding EMA performance. At a 4 mm thickness, the minimum reflection loss achieved was − 61.5 dB, and an impressive effective absorption bandwidth of 8.62 GHz was attained at 10.8 GHz. This achievement can be attributed to the exceptional dielectric, magnetic, and multiple reflections contributing to the superior EMA absorption performance, providing a broad band of frequencies.

Constructions and applications of MXene-based porous films

MXene-based films (MBFs) have a graphic structure composed of a horizontal arrangement of MXene thin tablets and/or layer interval parts. It usually has high electrode density, but high-rate charge transfer is limited, and ions are transmitted to oxidize the activity site. To overcome these problems, it is necessary to convert the plane configuration of the MXene membrane into an interactive structure with an open and porous architecture. In this paper, the first discovered and most widely studied Ti3C2Tx MXene materials are used as an example to introduce the unique construction methods of MXene-based porous film structures, structure-effect relationships, and the applications: supercapacitor, terahertz electromagnetic shielding, and flexible sensing, which show significantly improved performance.

Pillaring effect of nanodiamonds and expanded voltage window of Ti3C2Tx supercapacitors in AlCl3 electrolyte

MXenes have demonstrated excellent performance as constituent materials for supercapacitor electrodes. One of the most outstanding achievements is the capacitance obtained with 2D Ti3C2Tx in H2SO4 electrolyte, which is related to the O/OH titanium surface termination redox process. However, the narrow (under 1 V) potential window of highly acidic electrolytes is a limiting feature for many applications. In this scenario, materials and electrolytes that produce high capacitance and large potential windows are highly sought after. Herein, we used nanodiamonds (NDs) to pillar the Ti3C2Tx structure and obtain superior capacitive storage in AlCl3 electrolytes. The pillaring effect prevents the restacking of MXene layers, reducing diffusion limitations and resulting in a high-rate performance with a capacitance of 235 F/g (561 F/cm3). The use of 3 M AlCl3 provided protons that contributed to the capacitance obtained and allowed an expansion of the potential window to 1.2 V, due to the lowered activity of water in the electrolyte. The results reflect the need for a proper combination of electrode architecture and electrolyte formulation while providing a direction for the exploration of more efficient, safe, and inexpensive supercapacitor devices.