Facile synthesis of hierarchical MXene/ZIF-67/CNTs composite for electrochemical sensing of luteolin

Ultrasensitive electrochemical detection of gallic acid in beverages based on nitrogen-doped multi-walled carbon nanotube networks embellished with cobalt 2-methylimidazole nanoparticles

This work presents a convenient and easy-to-operate method for synthesizing the functionally integrated nanocomposite of nitrogen-doped multi walled carbon nanotube networks (N-CNTs) and cobalt 2-methylimidazole (ZIF-67) nanoparticles. The N-CNTs@ZIF-67 nanocomposite was utilized to design a novel electrochemical sensing platform for detecting gallic acid (GA). The N-CNTs@ZIF-67 modified glass carbon electrode (GCE) demonstrated high sensitivity for GA electrochemical detection (LOD: 10.17 nM, detection concentration: 0.5-20 μM). N-CNTs provided efficient electron transport channels for the GA electrochemical detection reaction, which improved the transfer rate of electrons/ions at the interface of sensing electrode/electrolyte. ZIF-67 nanoparticles with highly porous structure could adsorb GA molecules and promote the oxidation reaction. Besides that, N-CNTs provided more active sites on carbon nanotube networks by nitrogen-doping, which significantly enhanced the catalytic activity. The prepared N-CNTs@ZIF-67/GCE sensor exhibited favorable GA sensing detection performance, realizing an accurate analysis of GA in beverage samples (Recovery: 96.77-107.93 %, RSD: 1.07-4.38 %).

Post-modification of covalent organic framework functionalized aminated carbon nanotubes with active site (Fe) for the sensitive detection of luteolin

In this research, the TT-COF(Fe)@NH2-CNTs was innovatively prepared through a post-modification synthetic process functionalized TT-COF@NH2-CNTs with active site (Fe), where TT-COF@NH2-CNTs was prepared via a one-pot strategy using 5,10,15,20-tetrakis (para-aminophenyl) porphyrin (TTAP), 2,3,6,7-tetra (4-formylphenyl) tetrathiafulvalene (TTF) and aminated carbon nanotubes (NH2-CNTs) as raw materials. The complex TT-COF(Fe)@NH2-CNTs material possessed porous structures, outstanding conductivity and rich catalytic sites. Thus, it can be adopted to construct electrochemical sensor with glassy carbon electrode (GCE). The TT-COF(Fe)@NH2-CNTs/GCE can selectively detect luteolin (Lu) with a wide linear plot ranging from 0.005 to 3 μM and a low limit of detection (LOD) of 1.45 nM (S/N = 3). The Lu residues in carrot samples were determined using TT-COF(Fe)@NH2-CNTs sensor and UV-visible (UV-Vis) approach. This TT-COF(Fe)@NH2-CNTs/GCE sensor paves the way for the quantification of Lu through a cost-efficient and sensitive electrochemical approach, which can make a significant step in the sensing field based on crystalline COFs.

Monitoring of Specific Phytoestrogens by Dedicated Electrochemical Sensors: A Review

Phytoestrogens are non-steroidal estrogens produced from plants that can bind with the human body's estrogenic receptor site and be used as a substitute for maintaining hormonal balance. They are mainly classified as flavonoids, phenolic acids, lignans, stilbenes, and coumestans; some are resocyclic acids of lactones, which are mycotoxins and not natural phytoestrogen. Phytoestrogens have many beneficial medicinal properties, making them an important part of the daily diet. Electrochemical sensors are widely used analytical tools for analysing various pharmaceuticals, chemicals, pollutants and food items. Electrochemical sensors provide an extensive platform for highly sensitive and rapid analysis. Several reviews have been published on the importance of the biological and medicinal properties of phytoestrogens. However, this review provides an overview of recent work performed through electrochemical measurements with electrochemical sensors and biosensors for all the classes of phytoestrogens done so far since 2019.

Recent advances on metal-organic framework-based electrochemical sensors for determination of organic small molecules

Metal-organic frameworks (MOFs) are an extraordinarily versatile class of porous materials renowned for their intricate three-dimensional skeletal architectures and exceptional chemical properties. These extraordinary attributes have pushed MOFs into the vanguard of diverse disciplines such as microporous conduction, catalysis, separation, biomedical engineering, and electrochemical sensing. The focus of this review is to offer a comprehensive summary of recent advancements in designing MOF-based electrochemical sensors for detecting organic small molecules. offer a comprehensive survey of the recent progress in the methodologies adopted for the construction of MOF composites, covering template-assisted synthesis, Modification in synthesis, and post-synthesis modification. In addition, we discuss the practical application of MOF-based electrochemical sensors in the detection of organic small molecules. Our findings highlight the superior electrochemical sensing capabilities of these novel composites compared to those of their pristine counterparts. In conclusion, we provide a condensed perspective on the potential future trajectories in this domain, underscoring the impetus for continued enquiry and enhancement of MOF composite assemblies. With sustained investigation, the horizon appears bright for electrochemical sensing of small organic molecules and their myriad applications.

Holistic insights into carbon nanotubes and MXenes as a promising route to bio-sensing applications

Essential biosensor use has become increasingly important in drug discovery and recognition, biomedicine, food safety, security, and environmental research. It directly contributed to the development of specialized, reliable diagnostic instruments known as biosensors, which use biological sensing components. Traditional biosensors have poor performance, so scientists need to develop advanced biosensors with promising selectivity, sensitivity, stability, and reusability. These are all parameter modifications associated with the characteristics of the sensing material. Carbon nanotubes (CNTs) and MXenes are promising as targeted sensing agents in advanced functional materials because of their promising chemical and physical properties and limited toxic effects. Based on available data and sensing performance, MXene is better for biosensing applications than CNTs. Because of their large specific surface area (SSA), superior electrical conductivity, and adaptable surface chemistry that facilitates simple functionalization and robust interactions with biomolecules, MXenes are typically regarded as the superior option for biosensors. Additionally, because of their hydrophilic nature, they are more suited to biological settings, which increases their sensitivity and efficacy in identifying biological targets. MXenes are more suitable for biosensing applications due to their versatility and compatibility with aquatic environments, even if CNTs have demonstrated stability and muscular mechanical strength. However, MXenes offer better thermal stability, which is crucial for applications in diverse temperature environments. This study reviews and compares the biosensing capabilities, synthesis methods, unique properties, and toxicity of CNTs and MXenes. Both nanomaterials effectively detect various pollutants in food, biological substances, and human bodies, making them invaluable in environmental monitoring and medical diagnostics. In conclusion, CNTs work better for biosensors that must be strong, flexible, and long-lasting under different conditions. MXenes, on the other hand, work better when chemical flexibility and compatibility with wet environments are essential.

Bionanocomposite materials for electroanalytical applications: current status and future challenges

Bionanocomposites are materials composed of particles with at least one dimension in the range of 1-100 nm and a constituent of biological origin or biopolymers. They are the subject of current research interest as they provide exciting platforms and act as an interface between materials science, biology, and nanotechnology and find applications in disciplines such as electrochemistry, biomedicine, biosorption, aerospace, tissue engineering and packaging. They have different properties such as high conductivity, thermal stability, electrocatalytic ability, biocompatibility, adsorption ability and biodegradability, which can be tuned by their preparation methods, functionalities and applications. However, depending on the objective or the goal of a research project, specific preparation and characterization of bionanocomposites can be undertaken to understand the behavior and confirm the applicability of a bionanocomposite in a given field. Like in electroanalysis applications, electrode materials should be porous (meso- and macro-porosities), having large specific area (at least having a Brunauer-Emmett-Teller surface of 200 m2 g-1), higher stability over time with acceptable power recovery between 95% and 105%, good electrocatalytic ability, and be a good absorbent and a good conductor of electricity (that is to say, it facilitates the transfer of electrons from the solution to the surface of the electrode and vice versa). The present review focuses on the most used method of preparation of bionanocomposites with the critical aspect and their physicochemical and electrochemical characterization techniques, and finally, the practical situations of application of bionanocomposite materials as modified electrodes for electroanalysis of several groups of analytes and a comparison with non-bionanocomposite electrodes are discussed. The future scope of bionanocomposites in the field of electroanalysis is also addressed in this review. But before that, a general overview of bionanocomposite materials in relation to other types of materials is presented to avoid any misunderstanding.

A novel electrochemical sensor for detection of luteolin in food based on 3D networked electrically interconnected SiO2@GO/MXene composite

Luteolin (Lu), a compound with various biochemical and pharmacological activities beneficial to human health, has attracted researchers' attention. This study proposes an efficient and scalable method using ultrasound to intercalate graphene oxide (GO)-coated silica spheres (SiO2) into MXenes, resulting in a 3D conductive interconnected structural composite material. Characterization of the composite material was conducted using SEM, TEM, XRD, XPS, and Raman spectroscopy. MXenes exhibit excellent electrical conductivity, and the SiO2@GO surface with abundant hydroxyl and silanol groups provides high-binding active sites that facilitate Lu molecule enrichment. The formation of the 3D conductive interconnected structural composites enhances charge transport, significantly improving sensor sensitivity. Consequently, the sensor demonstrates excellent detection capabilities (detection range 0.03-7000 nM, detection limit 12 pM). Furthermore, the sensor can be applied to quantitative determination of Lu in real samples, including chrysanthemums, Jiaduobao, honeysuckle, purple perilla, and peanut shells, achieving recoveries between 98.2 and 104.7%.

MXene Hollow Spheres Supported by a C-Co Exoskeleton Grow MWCNTs for Efficient Microwave Absorption

High-performance microwave absorption (MA) materials must be studied immediately since electromagnetic pollution has become a problem that cannot be disregarded. A straightforward composite material, comprising hollow MXene spheres loaded with C-Co frameworks, was prepared to develop multiwalled carbon nanotubes (MWCNTs). A high impedance and suitable morphology were guaranteed by the C-Co exoskeleton, the attenuation ability was provided by the MWCNTs endoskeleton, and the material performance was greatly enhanced by the layered core-shell structure. When the thickness was only 2.04 mm, the effective absorption bandwidth was 5.67 GHz, and the minimum reflection loss (RLmin) was - 70.70 dB. At a thickness of 1.861 mm, the sample calcined at 700 °C had a RLmin of - 63.25 dB. All samples performed well with a reduced filler ratio of 15 wt%. This paper provides a method for making lightweight core-shell composite MA materials with magnetoelectric synergy.

Constructed MXene matrix composites as sensing material and applications thereof: A review

Most studies on MXene matrix composites for sensor development have primarily focused on synthesis and application. Nevertheless, there is currently a lack of research on how the introduction of different materials affects the sensing properties of these composites. The rapid development of MXene has raised intriguing questions about improving sensor performance by combining MXene with other materials such as polymers, metals and inorganic non-metals. This review will concentrate on the construction of MXene-based composites and explore ways to enhance their sensor applications. Specifically, this review describes why the introduction of materials to the system brings the advantage of low concentration and high sensitivity assays, as well as the MXene-based frameworks that have been recently investigated. Lastly, in order to capture the current trend of MXene-based composites in sensor applications and identify promising research directions, this review will critically evaluate the potential applications of newly developed MXene systems.

Ultrasensitive Ratiometric Electrochemiluminescence Sensor with an Efficient Antifouling and Antibacterial Interface of PSBMA@SiO2-MXene for Oxytetracycline Trace Detection in the Marine Environment

The sensitivity and accuracy of electrochemiluminescence (ECL) sensors for detecting small-molecule pollutants in environmental water are affected not only by nonspecific adsorption of proteins and other molecules but also by bacterial interference. Therefore, there is an urgent need to develop an ECL sensor with antifouling and antibacterial functions for water environment monitoring. Herein, a highly efficient antifouling sensing interface (PSBMA@SiO2-MXene) based on zwitterionic sulfobetaine methacrylate (SBMA) antifouling nanospheres (NPs) and two-dimensional MXene nanosheets was designed for the sensitive detection of oxytetracycline (OTC), an antibiotic small-molecule pollutant. Specifically, SBMA with good hydrophilicity and electrical neutrality was connected to SiO2 NPs, thus effectively reducing protein and bacterial adsorption and improving stability. Second, MXene with a high specific surface area was selected as the carrier to load more antifouling NPs, which greatly improves the antifouling performance. Meanwhile, the introduction of MXene also enhances the conductivity of the antifouling interface. In addition, a ratio-based sensing strategy was designed to further improve the detection accuracy and sensitivity of the sensor by utilizing Au@luminol as an internal standard factor. Based on antifouling and antibacterial interfaces, as well as internal standard and ratiometric sensing strategies, the detection range of the proposed sensor was 0.1 ng/mL to 100 μg/mL, with a detection limit of 0.023 ng/mL, achieving trace dynamic monitoring of antibiotics in complex aqueous media.

Electrochemistry of Flavonoids: A Comprehensive Review

Flavonoids represent a large group of aromatic amino acids that are extensively disseminated in plants. More than six thousand different flavonoids have been isolated and identified. They are important components of the human diet, presenting a broad spectrum of health benefits, including antibacterial, antiviral, antimicrobial, antineoplastic, anti-mutagenic, anti-inflammatory, anti-allergic, immunomodulatory, vasodilatory and cardioprotective properties. They are now considered indispensable compounds in the healthcare, food, pharmaceutical, cosmetic and biotechnology industries. All flavonoids are electroactive, and a relationship between their electron-transfer properties and radical-scavenging activity has been highlighted. This review seeks to provide a comprehensive overview concerning the electron-transfer reactions in flavonoids, from the point of view of their in-vitro antioxidant mode of action. Flavonoid redox behavior is related to the oxidation of the phenolic hydroxy groups present in their structures. The fundamental principles concerning the redox behavior of flavonoids will be described, and the phenol moiety oxidation pathways and the effect of substituents and experimental conditions on flavonoid electrochemical behavior will be discussed. The final sections will focus on the electroanalysis of flavonoids in natural products and their identification in highly complex matrixes, such as fruits, vegetables, beverages, food supplements, pharmaceutical compounds and human body fluids, relevant for food quality control, nutrition, and healthcare research.

Adsorption of hexavalent chromium, Rhodamine B and Congo red simultaneously in aquatic by zeolitic imidazolate framework coupling carbon nanotubes

Zeolitic imidazolate framework/carbon nanotube (ZIF-67/CNTs) was prepared by precipitation method. ZIF-67/CNTs maintained the characteristics of large specific surface area and high porosity of ZIFs, showing stable cubic structure. The adsorption capacities of ZIF-67/CNTs for Cong red (CR), Rhodamine B (RhB) and Cr(VI) were 36.82 mg/g, 1421.29 mg/g and 716.67 mg/g under the conditions of 2:1, 3:1 and 1:3 masses of ZIF-67 and CNTs, respectively. The optimum adsorption temperature of CR, RhB and Cr(VI) were 30 °C, and the removal rates at the adsorption equilibrium were 81.22%, 72.87% and 48.35%. The adsorption kinetic model of the three adsorbents on ZIF-67/CNTs was consistent with the quasi-second order reaction model, and the adsorption isotherms were more consistent with adsorption law of Langmuir. The adsorption mechanism for Cr(VI) was mainly electrostatic interaction, and the adsorption mechanism for azo dyes was the combination of physical and chemical adsorption. This study would provide theoretical basis for further developing metal organic framework (MOF) materials for environmental applications.

Rapid quantitative detection of luteolin using an electrochemical sensor based on electrospinning of carbon nanofibers doped with single-walled carbon nanoangles

In this study, single-walled carbon nanoangles/carbon nanofibers (SWCNHs/CNFs) were synthesized by electrospinning, followed by annealing in a N₂ atmosphere. The synthesized composite was structurally characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical sensor was fabricated by modifying a glassy carbon electrode (GCE) for luteolin detection, and its electrochemical characteristics were investigated using differential pulse voltammetry, cyclic voltammetry, and chronocoulometry. Under optimized conditions, the response range of the electrochemical sensor to luteolin was 0.01-50 μM, and the detection limit was 3.714 nM (S/N = 3). The SWCNHs/CNFs/GCE sensor showed excellent selectivity, repeatability, and reproducibility, thus enabling the development of an economical and practical electrochemical method for the detection of luteolin.

Emerging Trends and Recent Progress of MXene as a Promising 2D Material for Point of Care (POC) Diagnostics

Two-dimensional (2D) nanomaterials with chemical and structural diversity have piqued the interest of the scientific community due to their superior photonic, mechanical, electrical, magnetic, and catalytic capabilities that distinguish them from their bulk counterparts. Among these 2D materials, two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides with a general chemical formula of Mn+1XnTx (where n = 1-3), together known as MXenes, have gained tremendous popularity and demonstrated competitive performance in biosensing applications. In this review, we focus on the cutting-edge advances in MXene-related biomaterials, with a systematic summary on their design, synthesis, surface engineering approaches, unique properties, and biological properties. We particularly emphasize the property-activity-effect relationship of MXenes at the nano-bio interface. We also discuss the recent trends in the application of MXenes in accelerating the performance of conventional point of care (POC) devices towards more practical approaches as the next generation of POC tools. Finally, we explore in depth the existing problems, challenges, and potential for future improvement of MXene-based materials for POC testing, with the goal of facilitating their early realization of biological applications.

Rapid growth of MXene-based membranes for sustainable environmental pollution remediation

Water consumption has grown in recent years due to rising urbanization and industry. As a result, global water stocks are steadily depleting. As a result, it is critical to seek strategies for removing harmful elements from wastewater once it has been cleaned. In recent years, many studies have been conducted to develop new materials and innovative pathways for water purification and environmental remediation. Due to low energy consumption, low operating cost, and integrated facilities, membrane separation has gained significant attention as a potential technique for water treatment. In these directions, MXene which is the advanced 2D material has been explored and many applications were reported. However, research on MXene-based membranes is still in its early stages and reported applications are scatter. This review provides a broad overview of MXenes and their perspectives, including their synthesis, surface chemistry, interlayer tuning, membrane construction, and uses for water purification. Application of MXene based membrane for extracting pollutants such as heavy metals, organic contaminants, and radionuclides from the aqueous water bodies were briefly discussed. Furthermore, the performance of MXene-based separation membranes is compared to that of other nano-based membranes, and outcomes are very promising. In order to shed more light on the advancement of MXene-based membranes and their operational separation applications, significant advances in the fabrication of MXene-based membranes is also encapsulated. Finally, future prospects of MXene-based materials for diverse applications were discussed.

2D MXene-Based Biosensing: A Review

MXene emerged as decent 2D material and has been exploited for numerous applications in the last decade. The remunerations of the ideal metallic conductivity, optical absorbance, mechanical stability, higher heterogeneous electron transfer rate, and good redox capability have made MXene a potential candidate for biosensing applications. The hydrophilic nature, biocompatibility, antifouling, and anti-toxicity properties have opened avenues for MXene to perform in vitro and in vivo analysis. In this review, the concept, operating principle, detailed mechanism, and characteristic properties are comprehensively assessed and compiled along with breakthroughs in MXene fabrication and conjugation strategies for the development of unique electrochemical and optical biosensors. Further, the current challenges are summarized and suggested future aspects. This review article is believed to shed some light on the development of MXene for biosensing and will open new opportunities for the future advanced translational application of MXene bioassays.

Nitrogen-doped graphene-poly(hydroxymethylated-3,4-ethylenedioxythiophene) nanocomposite electrochemical sensor for ultrasensitive determination of luteolin

An ultrasensitive luteolin electrochemical sensor was constructed by co-electropolymerization of nitrogen-doped graphene (N-GR) and hydroxymethylated-3,4-ethylenedioxythiophene (EDOT-MeOH) using cyclic voltammetry (CV). Because of the synergistic effects of the large surface area, superior electrical conductivity, and large amount of chemically active sites of N-GR together with the satisfactory water solubility and high conductivity of poly(hydroxymethylated-3,4-ethylenedioxythiophene) (PEDOT-MeOH), the N-GR-PEDOT-MeOH nanocomposite sensor exhibited high electrochemical sensitivity towards luteolin with a wide linear range of 0.005-10.06 μM and low detection limit of 0.05 nM. Satisfactory reproducibility, selectivity, and stability were exhibited by this electrochemical sensor. Additionally, the proposed sensor was employed for trace-level analysis of luteolin in actual samples of herbal medicines (thyme (Thymus vulgaris L.), honeysuckle (Lonicera japonica Thunb.), and Tibetan Duyiwei (Lamiophlomis rotata (Benth.) Kudo)) with satisfactory results.

Fabrication of ionic liquid stabilized MXene interface for electrochemical dopamine detection

Development of MXene (Ti3C2Cl2)-based sensing platforms by exploiting their inherent active electrochemistry is highly challenging due to their characteristic poor stability in air and water. Herein, we report a cost-effective methodology to deposit MXene on a conductive graphitic pencil electrode (GPE). MXenes can provide active surface area due to their clever morphology of accordion-like sheets; however, the disposition to stack together limits their potential applications. A task-specific ionic liquid (1-methyl imidazolium acetate) is utilized as a multiplex host material to engineer MXene interface via π-π interactions as well as to act as a selective binding site for biomolecules. The resulting IL-MXene/GPE interface proved to be a highly stable interface owing to good interactions between MXene and IL that inhibited electrode leaching and boosted electron transfer at the electrode-electrolyte interface. It resulted in robust dopamine (DA) oxidation with amplified faradaic response and enhanced sensitivity (9.61 µA µM-1 cm-2) for DA detection. This fabricated sensor demonstrated large linear range (10 µM - 2000 µM), low detection limit (702 nM), high reproducibility, and good selectivity. We anticipate that such platform will pave the way for the development of stable and economically viable MXene-based sensors without sacrificing their inherent properties. Scheme 1 Schematic illustration of the IL-MXene/GPE fabrication and oxidative process towards non-enzymatic dopamine sensor.

A Comprehensive Review on the Electrochemical Sensing of Flavonoids

Flavonoids are bioactive polyphenolic compounds, widespread in the plant kingdom. Flavonoids possess broad-spectrum pharmacological effects due to their antioxidant, anti-tumor, anti-neoplastic, anti-mutagenic, anti-microbial, anti-inflammatory, anti-allergic, immunomodulatory, and vasodilatory properties. Care must be taken, since excessive consumption of flavonoids may have adverse effects. Therefore, proper identification, quantification and quality evaluations of flavonoids in edible samples are necessary. Electroanalytical approaches have gained much interest for the analysis of redox behavior and quantification of different flavonoids. Compared to various conventional methods, electrochemical techniques for the analysis of flavonoids offer advantages of high sensitivity, selectivity, low cost, simplicity, biocompatibility, easy on-site evaluation, high accuracy, reproducibility, wide linearity of detection, and low detection limits. This review article focuses on the developments in electrochemical sensing of different flavonoids with emphasis on electrode modification strategies to boost the electrocatalytic activity and analytical efficiency.

Methods of synthesis, characteristics, and environmental applications of MXene: A comprehensive review

MXene, comprised of two-dimensional transition metal carbides/nitride, has emerged as a novel material suitable for environmental remediation of toxic compounds. Due to their inherent and superior physical and chemical properties, MXene is employed in separation techniques like photocatalysis, adsorption, and membrane separation. MXene is equipped with a highly hydrophilic surface, ion exchange property, and robust surface functional groups. In this review paper, a comprehensive discussion on the structural patterns, preparation, properties of MXene and its application for the removal of toxic pollutants like Radionuclide, Uranium, Thorium, and dyes is presented. The mechanism of removal of the pollutants by MXene is extensively reviewed. Synthesis of MXene based membranes, their properties, and application for water purification and properties were also discussed. This review will be highly helpful to understand critically the methods of synthesis and use of MXene material for priority environmental pollutants removal. In addition, the challenges behind the synthesis and use of MXene for decontamination of pollutants were reviewed and reported.

Emerging MXene@Metal-Organic Framework Hybrids: Design Strategies toward Versatile Applications

Rapid progress on developing smart materials and design of hybrids is motivated by pressing challenges associated with energy crisis and environmental remediation. While emergence of versatile classes of nanomaterials has been fascinating, the real excitement lies in the design of hybrid materials with tunable properties. Metal-organic frameworks (MOFs) are the key materials for gas sorption and electrochemical applications, but their sustainability is challenged by limited chemical stability, poor electrical conductivity, and intricate, inaccessible pores. Despite tremendous efforts towards improving the stability of MOF materials, little progress has made researchers inclined toward developing hybrid materials. MXenes, a family of two-dimensional transition-metal carbides, nitrides and carbonitrides, are known for their compositional versatility and formation of a range of structures with rich surface chemistry. Hybridization of MOFs with functional layered MXene materials may be beneficial if the host structure provides appropriate interactions for stabilizing and improving the desired properties. Recent efforts have focused on integrating Ti₃C₂T_x and V₂CT_x MXenes with MOFs to result in hybrid materials with augmented electrochemical and physicochemical properties, widening the scope for emerging applications. This review discusses the potential design strategies of MXene@MOF hybrids, attributes of tunable properties in the resulting hybrids, and their applications in water treatment, sensing, electrochemical energy storage, smart textiles, and electrocatalysis. Comprehensive discussions on the recent efforts on rapidly evolving MXene@MOF materials for various applications and potential future directions are highlighted.

MXene/Carbon Nanotube Hybrids: Synthesis, Structures, Properties, and Applications

Since the successful preparation of few-layer transition metal carbides from three-dimensional MAX phases in 2011, MXenes (known as a family of layered transition metal carbides, nitrides, and carbonitrides) have been intensively studied. Though MXenes have been adopted as active materials in many applications, issues including aggregation and restacking are likely to hamper their potential applications. In order to address these prevailing challenges, the concept of MXene/carbon nanotube (CNT) hybrids was proposed initially in 2015, where CNTs were incorporated as the spacers and conductive additives. Ever since, MXene/CNT hybrids with different architectures have been synthesized by a number of methods and applied in numerous fields. Herein, after the discussion about general synthesis approaches, architectures, and properties of the hybrids, this Review summarized the recent advances in the application of MXene/CNT hybrids in energy storage devices, sensors, electrocatalysis, electromagnetic interference shielding, and water treatment, in which the function of individual components was clarified. In the end, the current research trend in this field were discussed and several technical issues were highlighted along with some suggestions on future research directions.

Metal-organic frameworks based hybrid nanocomposites as state-of-the-art analytical tools for electrochemical sensing applications

Metal-organic frameworks (MOFs) are remarkably porous materials that have sparked a lot of interest in recent years because of their fascinating architectures and variety of potential applications. This paper systematically summarizes recent breakthroughs in MOFs and their derivatives with different materials such as, carbon nanotubes, graphene oxides, carbon fibers, enzymes, antibodies and aptamers etc. for enhanced electrochemical sensing applications. Furthermore, an overview part is highlighted, which provides some insights into the future prospects and directions of MOFs and their derivatives in electrochemical sensing, with the goal of overcoming present limitations by pursuing more inventive ways. This overview can perhaps provide some creative ideas for future research on MOF-based materials in this rapidly expanding field.

Construction of a Tl(I) voltammetric sensor based on ZIF-67 nanocrystals: optimization of operational conditions via response surface design

An electroanalytical sensor was constructed constituted on a carbon paste electrode (CPE) with a ZIF-67 modifier and devoted to the quantification of Tl(I). Several characterization tests including XRD, BET, FT-IR, SEM/EDS/mapping, TEM, impedance spectroscopy (EIS), and cyclic voltammetry (CV) were performed on the synthesized ZIF-67 nanocrystals and CPE matrix. Central composite design (CCD) was used to assess the impact of variables affecting the sensor response, including the weight percent of ZIF-67 (14%), the pH of the thallium accumulation solution (6.4), and accumulation time (315 s) as well as the accumulation potential (-1.2 V). The direct linear relationship between the sensor response and the concentration of Tl(I) is in the interval of 1.0×10^-10 to 5.0×10^-7 M (coefficient of determination = 0.9994). The detection limit is approximately 1.0 × 10^-11 M. The right selection of the MOF makes this sensor highly resistant to the interference of other ions. High selectivity against common interferences in the measurement of thallium (such as Pb(II) and Cd(II)) is an important feature of this sensor. To confirm the performance of the prepared sensor, the amount of thallium in the real sample was determined.