Search Results (83)

Two-dimensional molybdenum carbide (Mo_1.33CT_x MXene) with ordered vacancies is one of the most promising materials for electrochemical energy storage. However, the high defectivity and tendency to aggregate of nanosheets hinders the large-scale fabrication of highly efficient Mo_1.33CT_x -based electrodes. In this study, Mo_1.33CT_x/carbon nanotubes (CNTs) electrodes of varying thicknesses were fabricated using a scalable doctor blade technique. Their electrochemical performance was studied in H₂SO₄, H₃PO₄, LiCl and KCl electrolytes using cyclic voltammetry and galvanostatic charge–discharge methods. Electrodes with an active material mass loading of 1.6 mg/cm² exhibited specific capacitances of 352, 287, 172, and 107 F/g in H₂SO₄, H₃PO₄, LiCl, and KCl electrolytes, respectively, at a scan rate of 2 mV/s. Increasing the mass loading of the electrode material to 3.5 mg/cm² resulted in a specific capacitance of 349, 260, 162 and 98 F/g in the same electrolytes. The incorporation of CNTs enabled rapid electrolyte ion transport throughout the electrode bulk, maintaining high capacitance values even at high scan rates. These results open new avenues for the development of high-performance electrode materials for supercapacitors. Full article

Nickel-based metal–organic frameworks (Ni-MOFs) have received enormous amounts of attention from the scientific community due to their excellent porosity, larger specific surface area, tunable structure, and intrinsic redox properties. In previous years, Ni-MOFs and their hybrid composite materials have been extensively explored for electrochemical sensing applications. As per the reported literature, Ni-MOF-based hybrid materials have been used in the fabrication of electrochemical sensors for the monitoring of ascorbic acid, glucose, L-tryptophan, bisphenol A, carbendazim, catechol, hydroquinone, 4-chlorophenol, uric acid, kaempferol, adenine, _L-cysteine, etc. The presence of synergistic effects in Ni-MOF-based hybrid materials plays a crucial role in the development of highly selective electrochemical sensors. Thus, Ni-MOF-based materials exhibited enhanced sensitivity and selectivity with reasonable real sample recovery, which suggested their potential for practical applications. In addition, Ni-MOF-based hybrid composites were also adopted as electrode modifiers for the development of supercapacitors. The Ni-MOF-based materials demonstrated excellent specific capacitance at low current densities with reasonable cyclic stability. This review article provides an overview of recent advancements in the utilization of Ni-MOF-based electrode modifiers with metal oxides, carbon-based materials, MXenes, polymers, and LDH, etc., for the electrochemical detection of environmental pollutants and biomolecules and for supercapacitor applications. In addition, Ni-based bimetallic and trimetallic catalysts and their composites have been reviewed for electrochemical sensing and supercapacitor applications. The key challenges, limitations, and future perspectives of Ni-MOF-based materials are discussed. We believe that the present review article may be beneficial for the scientific community working on the development of Ni-MOF-based materials for electrochemical sensing and supercapacitor applications. Full article

Sweat-based electrochemical sensors for wearable applications have attracted substantial interest due to their non-invasive nature, compact design, and ability to provide real-time data. Remarkable advancements have been made in integrating these devices into flexible platforms. While thin-film polymer substrates are frequently employed for their durability, the prolonged buildup of sweat on such materials can disrupt consistent sensing performance and adversely affect skin comfort over extended periods. Therefore, investigating lightweight, comfortable, and breathable base materials for constructing working electrodes is essential for producing flexible and breathable sweat electrochemical sensors. In this study, nylon fabric was chosen as the base material for constructing the working electrode. The electrode is prepared using a straightforward printing process, incorporating Ti₃C₂T_X MXene/polyaniline and methylene blue as modification materials in the electronic intermediary layer. The synergistic effect of the modified layer and the multi-level structure of the current collector enhances the electrochemical kinetics on the electrode surface, improves electron transmission efficiency, and enables the nylon fabric-based electrode to accurately and selectively measure glucose concentration in sweat. It exhibits a wide linear range (0.04~3.08 mM), high sensitivity (3.11 μA·mM⁻¹), strong anti-interference capabilities, and high stability. This system can monitor glucose levels and trends in sweat, facilitating the assessment of daily sugar intake for personal health management. Full article

MXenes, a class of two-dimensional transition metal carbides and nitrides, emerged as a promising material for next-generation energy storage and corresponding applications due to their unique combination of high electrical conductivity, tunable surface chemistry, and lamellar structure. This review highlights recent advances in MXene-based composites, focusing on their integration into electrode architectures for the development of supercapacitors, batteries, and multifunctional devices, including triboelectric nanogenerators. It serves as a comprehensive overview of the multifunctional capabilities of MXene-based composites and their role in advancing efficient, flexible, and sustainable energy and sensing technologies, outlining how MXene-based systems are poised to redefine multifunctional energy platforms. Electrochemical performance optimization strategies are discussed by considering surface functionalization, interlayer engineering, scalable synthesis techniques, and integration with advanced electrolytes, with particular attention paid to the development of hybrid supercapacitors, triboelectric nanogenerators (TENGs), and wearable sensors. These applications are favored due to improved charge storage capability, mechanical properties, and the multifunctionality of MXenes. Despite these aspects, challenges related to long-term stability, sustainable large-scale production, and environmental degradation must still be addressed. Emerging approaches such as three-dimensional self-assembly and artificial intelligence-assisted design are identified as key challenges for overcoming these issues. Full article

This review article compiled previous reports in the fabrication of hydroquinone (HQ) electrochemical sensors using differently modified electrodes. The electrode materials, which are also called electrocatalysts, play a crucial role in electrochemical detection of biomolecules and toxic substances. Metal oxides, MXenes, carbon-based materials such as reduced graphene oxide (rGO), carbon nanotubes (CNTs), layered double hydroxides (LDH), metal sulfides, and hybrid composites were extensively utilized in the fabrication of HQ sensors. The electrochemical performance, including limit of detection, linearity, sensitivity, selectivity, stability, reproducibility, repeatability, and recovery for real-time sensing of the HQ sensors have been discussed. The limitations, challenges, and future directions are also discussed in the conclusion section. It is believed that the present review article may benefit researchers who are involved in the development of HQ sensors and catalyst preparation for electrochemical sensing of other toxic substances. Full article

Recently, it has been found that electrochemical sensing technology is one of the significant approaches for the monitoring of toxic and hazardous substances in food and the environment. Nitrofurazone (NFZ) and nitrofurantoin (NFT) possess a hazardous influence on the environment, aquatic life, and human health. Thus, various advanced materials such as graphene, carbon nanotubes, metal oxides, MXenes, layered double hydroxides (LDHs), polymers, metal–organic frameworks (MOFs), metal-based composites, etc. are widely used for the development of nitrofurazone and nitrofurantoin sensors. This review article summarizes the progress in the fabrication of electrode materials for nitrofurazone and nitrofurantoin sensing applications. The performance of the various electrode materials for nitrofurazone and nitrofurantoin monitoring are discussed. Various electrochemical sensing techniques such as square wave voltammetry (SWV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), amperometry (AMP), cyclic voltammetry (CV), and chronoamperometry (CA) are discussed for the determination of NFZ and NFT. It is observed that DPV, SWV, and AMP/CA are more sensitive techniques compared to LSV and CV. The challenges, future perspectives, and limitations of NFZ and NFT sensors are also discussed. It is believed that present article may be useful for electrochemists as well materials scientists who are working to design electrode materials for electrochemical sensing applications. Full article

In recent decades, flexible electronics have witnessed remarkable advancements in multiple fields, encompassing wearable electronics, human–machine interfaces (HMI), clinical diagnosis, and treatment, etc. Nevertheless, conventional rigid electronic devices are fundamentally constrained by their inherent non-stretchability and poor conformability, limitations that substantially impede their practical applications. In contrast, conductive hydrogels (CHs) for electronic skin (E-skin) and healthcare monitoring have attracted substantial interest owing to outstanding features, including adjustable mechanical properties, intrinsic flexibility, stretchability, transparency, and diverse functional and structural designs. Considerable efforts focus on developing CHs incorporating various conductive materials to enable multifunctional wearable sensors and flexible electrodes, such as metals, carbon, ionic liquids (ILs), MXene, etc. This review presents a comprehensive summary of the recent advancements in CHs, focusing on their classifications and practical applications. Firstly, CHs are categorized into five groups based on the nature of the conductive materials employed. These categories include polymer-based, carbon-based, metal-based, MXene-based, and ionic CHs. Secondly, the promising applications of CHs for electrophysiological signals and healthcare monitoring are discussed in detail, including electroencephalogram (EEG), electrocardiogram (ECG), electromyogram (EMG), respiratory monitoring, and motion monitoring. Finally, this review concludes with a comprehensive summary of current research progress and prospects regarding CHs in the fields of electronic skin and health monitoring applications. Full article

In enzymatic reaction glucose detection chips, the enzyme can easily dislodge from the electrode, which harms both the chip and test stability. Additionally, enzyme activity significantly decreases at low temperatures. Consequently, immobilizing the enzyme at the appropriate substrate and ambient temperature is a critical step for improving the chip. To address this issue, an electrochemical detection chip was modified using the nanomaterial MXene, known for its large specific surface area, excellent adsorption, good dispersion, and high conductivity. Meanwhile, AgNO₃ solution was added to the Ti₃C₂T_x MXene nanosheet solution, and the AgNP@MXene material was prepared by heating in a water bath. This process further enhances photothermal conversion efficiency due to the localized surface plasmon resonance effect of silver nanoparticles and MXene. This MXene-based photothermally enhanced paper chip exhibits outstanding photothermal conversion performance and sensitive photoelectrochemical responsiveness, along with good cycling stability. Moreover, improved glucose detection sensitivity at low winter temperatures has been achieved, and the ambient temperature range of the paper chip has been expanded to 25–37 °C. Full article

The transition toward sustainable and decentralized energy solutions necessitates the development of innovative bioelectronic systems capable of harvesting and converting renewable energy. Here, we present a novel photo-bioelectrochemical fuel cell architecture based on a biohybrid anode integrating laser-induced graphene (LIG), poly(3,4-ethylenedioxythiophene) (PEDOT), and isolated thylakoid membranes. LIG provided a porous, conductive scaffold, while PEDOT enhanced electrode compatibility, electrical conductivity, and operational stability. Compared to MXene-based systems that involve complex, multi-step synthesis, PEDOT offers a cost-effective and scalable alternative for bioelectrode fabrication. Thylakoid membranes were immobilized onto the PEDOT-modified LIG surface to enable light-driven electron generation. Electrochemical characterization revealed enhanced redox activity following PEDOT modification and stable photocurrent generation under light illumination, achieving a photocurrent density of approximately 18 µA cm⁻². The assembled photo-bioelectrochemical fuel cell employing a gas diffusion platinum cathode demonstrated an open-circuit voltage of 0.57 V and a peak power density of 36 µW cm⁻² in 0.1 M citrate buffer (pH 5.5) under light conditions. Furthermore, the integration of a charge pump circuit successfully boosted the harvested voltage to drive a low-power light-emitting diode, showcasing the practical viability of the system. This work highlights the potential of combining biological photosystems with conductive nanomaterials for the development of self-powered, light-driven bioelectronic devices. Full article

Detection of multiple analytes in biofluids is of significance for early disease diagnosis, effective treatment monitoring, and accurate prognostic assessment. Electrochemical sensors have emerged as a promising tool for the multiplexed detection of biofluids due to their low cost, high sensitivity, and rapid response. Two-dimensional transition metal carbon/nitride MXene, which has the advantages of a large specific surface area, good electrical conductivity, and abundant surface functional groups, has received increasing attention in the electrochemical sensing field. This paper systematically reviews the advances of MXene-based electrochemical sensors for multiplexed detection in biofluids, emphasizing the design of MXene-based electrode materials as well as the strategies for distinguishing multiple signals during simultaneous electrochemical analysis. In addition, this paper critically analyzes the existing challenges of MXene-based electrochemical sensors for multiplexed detection of biofluids and proposes future development directions for this field. The ultimate goal is to improve biofluid multiplexed detection technology for clinical medical applications. Full article

Developing flexible sensors that combine high sensitivity, a wide detection range, and comfortable wearability remains a key challenge in the development of electronic skin. This study presents a breathable, highly sensitive, and wearable piezoresistive sensor based on the preparation of hierarchical microporous PU@MXene + CNT films and single-sided electrodes using a simple and effective method. Distilled water was used as a non-solvent to induce the separation of polyurethane films (PU) with different mass fractions, forming a gradient porous structure with inconsistent pore morphologies in the upper and lower layers. Three-dimensional structure analysis of the hierarchical porous films with varying gradients, conducted using computed tomography, revealed that the porous structures formed after phase separation of PU solutions with different mass fractions exhibited different morphologies. As the mass fraction increased, the pore size, pore volume, and porosity gradually decreased while the surface area gradually increased. The greater the gradient of the constructed porous film, the more significant the difference between the upper- and lower-layer structures. A flexible sensor prepared using the PU@MXene + CNT porous film with the largest gradient exhibited excellent sensitivity in a wide detection range from 0.7 to 20 kPa, which was higher than that of porous films with other gradients, demonstrating high stability (>8000 cycles). The air permeability and moisture permeability of PU@MXene + CNT with the largest gradient were 0.9922 L/m²/s and 1123.6 g/m²/day, respectively, and these values were 1.35 and 4.40 times those of the non-porous film. Therefore, the constructed flexible piezoresistive sensor with a gradient porous structure had both high sensitivity and wide detection range, as well as good air and moisture permeability. Finally, the sensor successfully monitored human movements, including throat activity, finger motions, and arm bending, demonstrating its potential for wearable electronic applications. Full article

With the rapid development of electrical energy storage technologies, traditional battery systems are limited in practical applications by insufficient energy density and short cycle life. This review provides a comprehensive and critical summary of MXene or MXene-based composites as electrode materials for high-performance energy storage devices. By integrating the synthesis techniques of MXenes that have been studied, this paper systematically illustrates the physicochemical properties, synthesis strategies, and mechanisms of MXenes, and analyzes the bottlenecks in their large-scale preparation. Meanwhile, it collates the latest research achievements of MXenes in the field of metal–ion batteries in recent years, focusing on integrating their latest progress in lithium–ion, sodium–ion, lithium–sulfur, and multivalent ion (Zn²⁺, Mg²⁺, Al³⁺) batteries, and reveals their action mechanisms in different electrode material cases. Combining DFT analysis of the effects of surface functional groups on adsorption energy with experimental studies clarifies the structure–activity relationships of MXene-based composites. However, the development of energy storage electrode materials using MXenes and their hybrid compounds remains in its infancy. Future development directions for MXene-based batteries should focus on understanding and regulating surface chemistry, investigating specific energy storage mechanisms in electrodes, and exploring and developing electrode materials related to bimetallic MXenes. Full article

The advent of the Internet of Things has boosted portable and wearable miniature electronics, especially micro-supercapacitors (MSCs) with excellent integrated performance as well as high-power density and a long lifetime. However, the rational design of electrode material formulations and the construction of three-dimensional (3D) structured electrodes with scalable and cost-effective fabrication remains an arduous task for improving the energy density of MSCs to meet all industrial sector requirements, such as the mass-production of microscale structures, a lasting power supply, and safety. To address these challenges, combining the respective capacitance merits of MXenes and polyaniline (PANI), we propose a constructing strategy for the preparation of a 3D MXene@PANI hierarchical architecture consisting of one-dimensional (1D) PANI nanofibers grown on two-dimensional (2D) Ti₃C₂ MXene nanosheets via extrusion-based 3D printing. Such a 3D architecture not only achieves a high loading mass of MSC electrodes prior to conventional planar MSCs for abundant active site exposure, but it also overcomes the restacking of MXene nanosheets accounting for sluggish ionic kinetics. These features enable the resulting MSCs to deliver excellent electrochemical properties, including a high volumetric capacitance of 1638.3 mF/cm³ and volumetric energy density of 328.2 mWh/cm³. This power supply ability is further demonstrated by lighting up a blue bulb or powering an electronic thermometer. This study provides a promising design strategy of the architecture of MXene@PANI composites for high-performance MSCs with 3D printing technology. Full article

As new materials are required to overcome the challenges presented by non-volatile resistive switching (RS) devices, organic based composites are gaining attention due to their easy preparation, tunability, scalability and good mechanical properties. Here, we study how the interaction between MXene and Polyvinylidene fluoride (PVDF) contribute to the RS phenomenon, and how different electrode materials [Ag (top) and W, ITO (bottom)] affect the conduction in these devices. Our detailed structural and electrical analyses of the composite layer reveals that the RS mechanism is related with the formation and rupture of conductive filaments pinned by the MXene sites. The W-based structure exhibits lower switching voltage (<1 V) and a higher ON/OFF resistance ratio of 15. In contrast, the ITO-based structure requires a higher bias voltage and displays a more gradual switching (ON/OFF ratio of 3), likely due to the competition between the migration of Ag⁺ ions and oxygen vacancies from ITO. This work paves the way in understanding how to exploit the integration of novel two-dimensional (2D) materials with polymers for neuromorphic computing. Full article

An electrochemically active and promising binary composite that is made up of titanium-based MXene (Ti₃C₂T_x) and rGO is developed to simultaneously detect the Cd²⁺ and Cu²⁺, in water. XRD, FTIR, Raman, XPS, FESEM, elemental mapping, and EDX analysis affirmed the successful formation of the Ti₃C₂T_x-rGO composite. The produced Ti₃C₂T_x-rGO electrode exhibited a homogeneous rGO sheet covering the Ti₃C₂T_x MXene plates with all the detailed Ti2p, C1s, and O1s XPS peaks. The high-performance Ti₃C₂T_x-rGO composite was successfully tested for the Cd²⁺ and Cu²⁺ ions via differential pulse voltammetry (DPV), altering the pH, concentration, and the real water sample’s quality. The electrochemical performances revealed that the proposed Ti₃C₂T_x-rGO composite depicted excellent detection and quantification limits (LOD and LOQ) for both Cd²⁺ (LOD = 0.31 nM, LOQ = 1.02 nM) and Cu²⁺ (LOD = 0.18 nM, LOQ = 0.62 nM) ions, where the result is highly comparable with the reported literature. The Ti₃C₂T_x-rGO was proven highly sensitive towards Cd²⁺ (0.345 μMμA⁻¹) and Cu²⁺ (0.575 μMμA⁻¹) with great repeatability and reproducibility properties. The Ti₃C₂T_x-rGO electrode also exhibited excellent stability over four weeks with a retention of 97.86% and 98.01% for Cd²⁺ and Cu²⁺, respectively. This simple modification of Ti₃C₂T_x with rGO can potentially be advantageous in the development of highly sensitive electrochemical sensors for the simultaneous detection of heavy metal ions. Full article