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A new single-step method is suggested to fabricate block structures consisting of NH4TiOF3 wrapped around Ti3C2 MXene (Ti3C2) by etching Ti3AlC2 MAX phase with (NH4)2TiF6. The optimal reaction conditions for Ti3AlC2 MAX phase and (NH4)2TiF6 are systematically investigated. (NH4)2TiF6 selectively etches the Al in the Ti3AlC2 MAX phase and promotes promoting the mild hydrolysis reaction of (NH4)2TiF6 to form NH4TiOF3 crystals. The exterior shapes of Ti3C2/NH4TiOF3 hybrids can be tuned by adjusting the reagent concentration, reaction temperature. The phase composition, morphology and photophysical properties of the Ti3C2/NH4TiOF3 hybrids are investigated using various characterization techniques. Ti3AlC2 MAX phase reacts with (NH4)2TiF6 at 60 °C for 24 h to form hybrids which are surrounded by NH4TiOF3 crystals simultaneously with the formation of Ti3C2 nanosheet. The resulting Ti3C2/NH4TiOF3 are porous and finely structured, showing potential for various applications in biotechnology, sensing, and environmental fields. This method provides important insights into future applications of Ti3C2/NH4TiOF3 hybrids.

About one decade after the first report on MXenes, these 2D early transition metal carbides or nitrides have become among the best‐performing materials in electrode applications related to electrical energy storage devices and power‐to‐fuels conversion. MXenes are obtained by a top‐down approach starting from the appropriate 3D MAX phase that undergoes etching of the A‐site metal. Initial etching procedures are based on the use of concentrated HF or the in situ generation of this highly corrosive and poisonous reagent. Etching of the MAX phase is one of the major hurdles limiting the progress of the field. The present review summarizes an alternative, universal, and easily scalable etching procedure based on treating the MAX precursor with a Lewis acid molten salt. The review starts with presenting the current state of the art of the molten salt etching procedure to obtain or modify MXene, followed by a summary of the applications of these MXene samples. The aim of the review is to show the versatility and advantages of molten salt etching in terms of general applicability, control of the surface terminal groups, and uniform deposition of metal nanoparticles, among other features of the procedure. Synthesis methods of MXenes are rapidly advancing with the use of halide molten salt etchants. One‐step synthesis of MXene‐metal nanoparticle hybrids are enabled, and new areas of MXene surface chemistry are unlocked to include heavier halogens, and chalcogens by post‐synthetic substitution. Herein, molten salt synthesis of MXene and MXene‐hybrids and their applications in catalysis and energy storage are reviewed.

To meet the energy needs batteries and supercapacitors are evolved as a promising candidate from the class of energy storage devices. The growth in the development of new 2D electrode materials brings a new revolution in energy storage devices with a comprehensive investigation. MXene, a new family of 2D metal carbides, nitrides and carbonitrides due to their attractive electrical and electrochemical properties e.g. hydrophilicity, conductivity, surface area, topological structure have gained huge attention. In this review, we discussed different MXene synthesis routes using different etchants e.g. hydrofluoric acid, ammonium hydrazine, lithium fluoride, and hydrochloric acid, etc showing that fluorine formation is compulsory to etch the aluminum layer from its precursor. Due to the advantage of large interlayer spacing between the MXene layers in MXene, the effect of intercalation on the performance of batteries and supercapacitors using MXene as electrodes by various sized cations are reviewed. Different MXene hybrids as supercapacitor electrodes will also be summarized. Lastly, the conclusion and future scope of MXene to be done in various supercapacitor applications are also presented.

Atmospheric pressure plasma (APP) etching has been developed recently into a manufacturing technique for silicon-based materials used for large optical lenses. However, there are few reports published regarding APP etching of non-silicon-based materials. We report here the development of an APP process using SF6 for the etching of Ti-6Al-4 V metal alloy. Ti-6Al-4V is extensively used in aerospace and biomedical fields for its excellent properties; however, these properties also make it difficult to machine. Current techniques such as precision grinding and laser polishing can be slow, energy intensive, and cause damages and defects which reduce the lifetime of vital components. The results in this paper demonstrate effective material removal and little surface damage by APP etching of Ti-6Al-4V. Material removal rates between 0.5 and 2 mm3 min−1 were obtained, and the proposed material removal mechanism is through the formation of volatile VFx and TiF4. These results show that APP etching is a promising technique for surface finishing of Ti-6Al-4V, particularly for large- and complex-shaped components.

It is highly desirable to develop sensors with high response and selectivity at room temperature of operating temperature. Besides, efficient and low-cost sensors are also required for future social development. In this paper, it is developed a detector with two-dimensional (2D) material of Ti 3 C 2 T x MXene sensing material by a chemical etchant for ammonia sensing, which shows high response and excellent selectivity to ammonia (NH 3 ) at room temperature of operating temperature. A key point of this work is the thermal treatment temperature of the sensing ceramic tube at 280 °C, which removes the adsorbed water and partially oxidized the material. In ambient condition, Ti 3 C 2 T x MXene-280 shows the response to 500 ppm NH 3 with 147 %, and the counterpart response and recovery time are 67 and 157 s at room temperature of operating temperature, respectively. In the environment of different relative humidity, its sensing performance is maintained at around 50 % of the initial performance, which shows great moisture resistance. The higher response and good selectivity of Ti 3 C 2 T x MXene-280 sensor to NH 3 at room temperature are ascribed to the powerful hydrogen bond formed between the OH − , O 2 −  functional groups on Ti 3 C 2 T x MXene-280 and NH 3 , as well as the synergistic effect of TiO 2 and Ti 3 C 2 T x MXene, generated after heating treatment, which increases the electron transport efficiency. The results demonstrated that the facilely designed Ti 3 C 2 T x MXene-280 sensor is believed to contribute to developing future portable and selective sensing electronics at room temperature.

Graphene is a 2D material with fruitful electrical properties, which can be efficiently prepared, tailored, and modified for a variety of applications, particularly in the field of optoelectronic devices thanks to its planar hexagonal lattice structure. To date, graphene has been prepared using a variety of bottom–up growth and top–down exfoliation techniques. To prepare high‐quality graphene with high yield, a variety of physical exfoliation methods, such as mechanical exfoliation, anode bonding exfoliation, and metal‐assisted exfoliation, have been developed. To adjust the properties of graphene, different tailoring processes have been emerged to precisely pattern graphene, such as gas etching and electron beam lithography. Due to the differences in reactivity and thermal stability of different regions, anisotropic tailoring of graphene can be achieved by using gases as the etchant. To meet practical requirements, further chemical functionalization at the edge and basal plane of graphene has been extensively utilized to modify its properties. The integration and application of graphene devices is facilitated by the combination of graphene preparation, tailoring, and modification. This review focuses on several important strategies for graphene preparation, tailoring, and modification that have recently been developed, providing a foundation for its potential applications. Graphene is a key material for a new generation of electronic devices with unique electrical properties. In this review, current advances in the preparation, tailoring, and modification of graphene to obtain high‐quality graphene with precisely controlled patterning and specific functional groups are summarized.

Single-crystalline membranes of functional materials enable the tuning of properties via extreme strain states; however, conventional routes for producing membranes require the use of sacrificial layers and chemical etchants, which can both damage the membrane and limit the ability to make them ultrathin. Here we demonstrate the epitaxial growth of the cubic Heusler compound GdPtSb on graphene-terminated Al 2 O 3 substrates. Despite the presence of the graphene interlayer, the Heusler films have epitaxial registry to the underlying sapphire, as revealed by x-ray diffraction, reflection high energy electron diffraction, and transmission electron microscopy. The weak Van der Waals interactions of graphene enable mechanical exfoliation to yield free-standing GdPtSb membranes, which form ripples when transferred to a flexible polymer handle. Whereas unstrained GdPtSb is antiferromagnetic, measurements on rippled membranes show a spontaneous magnetic moment at room temperature, with a saturation magnetization of 5.2 bohr magneton per Gd. First-principles calculations show that the coupling to homogeneous strain is too small to induce ferromagnetism, suggesting a dominant role for strain gradients. Our membranes provide a novel platform for tuning the magnetic properties of intermetallic compounds via strain (piezomagnetism and magnetostriction) and strain gradients (flexomagnetism). Single crystalline membranes enable the tuning of materials properties via strain states that are not accessible to bulk crystals or epitaxially clamped films. Here, the authors demonstrate the synthesis and strain gradient-induced magnetism in membranes of the Heusler compound GdPtSb.

High-entropy oxides (HEOs) consist of multiple principal metal cations and oxygen anions, which enhances compositional versatility and promotes the emergence of atypical properties within oxide materials. Nonetheless, precisely shaping HEOs in hollow nanostructures remains a significant challenge due to the disparate nucleation and growth kinetics of the various metal oxide compositions in HEOs. Herein, we present a strategy for the synthesis of multicomponent hollow nanocubes HEOs libraries from ternary to octonary. We utilized a template-assisted route inspired by coordinating etching and integrating thermal treatment to synthesize HEOs hollow nanocubes through the selection of coordinating etchant and optimization of the reaction conditions. This approach demonstrates the potential for precisely designing high-quality HEOs hollow nanocubes with diverse compositions at low temperature, with promising prospects for various applications. A template-assisted route inspired by coordinating etching was utilized for the synthesis of noble metal-free, ternary through octonary, hollow HEO nanocubes through optimization of the coordinating etchant and reaction conditions.

Conventional etchants for multi-metal/alloy stacked structures often suffer from nonuniform etching, residual layers, or undercutting, failing to meet high-generation production standards. This study presents a stable copper-molybdenum (Cu-Mo) etchant with extended bath life for thin film transistor liquid crystal display (TFT-LCD) applications, achieved through compositional optimization. Systematic investigations have been conducted on the effects of etching time, copper ion (Cu2+) loading (bath life) and storage time on the etch performance, alongside evaluations of sudden-eruption point and material compatibility. Results demonstrate that over-etching beyond the “detected endpoint” by 10% to 90% maintains critical dimension (CD) bias and taper angle of MoNiTi(MTD)/Cu/MTD three-layer and Cu/MTD two-layer within process specifications, as well as the difference between the CD bias of the three-layer and two-layer structures at the same over-etch time. The optimized formulation exhibits a 20% broader process window and 20% longer bath life compared to the process-of-record (POR) etchant. Shelf stability exceeds 15 days with minimal performance degradation, while maintaining compatibility with industrial equipment materials. These advancements address key challenges in high-precision etching for advanced TFT-LCD manufacturing, providing a scalable solution for next-generation display production.

The effect of etching environment (opened or closed) on the synthesis and electrochemical properties of V 2 C MXene was studied. V 2 C MXene samples were synthesized by selectively etching of V 2 AlC at 90 °C in two different environments: opened environment (OE) in oil bath pans under atmosphere pressure and closed environment (CE) in hydrothermal reaction kettles under higher pressures. In OE, only NaF (sodium fluoride) + HCl (hydrochloric acid) etching solution can be used to synthesize highly pure V 2 C MXene. However, in CE, both LiF (lithium fluoride) + HCl and NaF+HCl etchant can be used to prepare V 2 C MXene. Moreover, the V 2 C MXene samples made in CE had higher purity and better-layered structure than those made in OE. Although the purity of V 2 C obtained by LiF+HCl is lower than that of V 2 C obtained using NaF+HCl, it shows better electrochemical performance as anodes of lithium-ion batteries (LIBs). Therefore, etching in CE is a better method for preparing highly pure V 2 C MXene, which provides a reference for expanding the synthesis methods of V 2 C with better electrochemical properties.