The increasing global prevalence of diabetes mellitus necessitates the development of reliable, cost-effective continuous glucose monitoring systems with high temporal resolution and analytical accuracy. Herein, we report a mechanically robust and structurally flexible non-enzymatic glucose sensor based on a hierarchically architected Cu+/Cu2+-laser-induced graphene (Cu+/Cu2+–LIG) composite, fabricated via a facile and spatially controlled laser re-scribing technique. This localized photothermal effect facilitates the precise in situ nucleation, growth, and anchoring of mixed-valence copper oxide nanoparticles onto a three-dimensional porous LIG. Comprehensive structural and chemical characterizations confirmed the stable coexistence of Cu+ (Cu2O) and Cu2+ (CuO) phases within the composite matrix. This dual-valence system generates a pronounced synergistic effect, whereby the Cu+ phase functions as an efficient electron-transport pathway that accelerates interfacial charge-transfer kinetics. In contrast, the Cu2+ phase provides highly active catalytic sites for glucose electrooxidation. The fabricated sensor exhibited superior electrochemical performance, including a rapid response time (approximately 3 s), an extended linear dynamic range (up to 6.0 mM), high analytical sensitivity, and a low relative standard deviation of 3.49%, confirming excellent reproducibility. Furthermore, the device demonstrated exceptional selectivity against common physiological interferents and maintained high electrochemical and operational stability under prolonged testing conditions. Mechanical flexibility tests revealed negligible performance deviation (within 90%–110% of initial response) under extreme bending stress ranging from -135° to 135°, thereby validating the suitability of the Cu+/Cu2+–LIG platform for next-generation wearable healthcare applications.

This study reports a bottom-up hybrid synthesis of MoS2/Graphene heterostructures and investigates the relationship between their structural properties and electrochemical performance for high-performance supercapacitor. The MoS2 layer was directly synthesized on chemical vapor deposition graphene through electrochemical deposition using (NH4)2MoS4 as a precursor, followed by thermal annealing. Electrochemical performance demonstrated that while pristine graphene and thin MoS2 layer exhibited distorted Cyclic voltammetry (CV) curves, but the electrode with a thick MoS2 layer exhibited a stable rectangular CV shape with significantly improved capacitance. The high-performance MoS2/Graphene electrode featured a uniform, high-density nanocluster structure. The nano-crystalline structure maximized the surface area, enabling the device to achieve a specific areal capacitance of 2.22 mF/cm2 and a specific volumetric capacitance of 584.21 F/cm3, attributed to its thin structure. The device employed a PVA/H2SO4 solid-state electrolyte and maintained high-speed charge-discharge characteristics. These results provide a significant strategy for the nanostructured energy storage devices using hybrid materials.

Non-enzymatic biosensors are promising alternatives to enzyme-based sensors for personalized health monitoring because they offer lower cost, improved stability, and simpler fabrication. Nevertheless, their practical use remains limited by insufficient sensitivity, selectivity, and long-term stability, highlighting the need for robust and highly functional nanomaterial-based sensing platforms. In this study, we developed a laser-induced graphene (LIG) electrode modified with copper oxide (CuxO, comprising coexisting Cu2O and CuO phases) for use in non-enzymatic biosensing applications. Systematic surface analysis confirmed the successful formation of CuxO on the LIG structure. The incorporation of CuxO nanoparticles significantly increased the surface area of the electrode, providing abundant active sites and enhancing its electrochemical properties. Owing to the unique redox mechanism of CuxO, the sensor was able to selectively and sensitively detect both glucose and creatinine. The CuxO-LIG sensor exhibited sensitive detection for glucose and creatinine within the ranges of 0-5.5 mM and 0-0.5 mM, with limits of detection of 84 mu M and 5.4 mu M, respectively. Moreover, well-separated oxidation potentials for glucose (0.65 V) and creatinine (0.04 V), enabled simultaneous detection. These results demonstrate the potential of the CuxO-LIG platform as a robust non-enzymatic biosensor for multi-biomarker monitoring in healthcare applications.

Liquid-based direct exfoliation (LDE) has become a highly attractive top-down route for producing hexagonal boron nitride (h-BN) nanomaterials in a scalable and cost-efficient manner. In contrast to bottom-up techniques such as chemical vapor deposition or solvothermal growth, which provide excellent crystallinity but remain limited by high cost and low throughput, liquid-based direct exfoliation allows the production of boron nitride nanosheets (BNNSs) while retaining their original chemical stability, electrical insulation, and layered crystalline structure. However, achieving high-yield, maintaining large lateral size, and selecting exfoliation solvent continue to pose significant challenges that hinder industrial transformation. This review offers a comprehensive examination of the production methods and applications that govern exfoliation efficiency across direct ultrasonic, polymer-assisted, functionalization-hybridization, and metal-assisted strategies. Quantitative performance comparisons highlight how cavitation dynamics, solvent solute compatibility, and interfacial stabilization dictate flake thickness, yield, and dispersion stability. The technological relevance of LDE h-BN is further demonstrated through its dramatically expanding applications in thermal interface materials, dielectric layers, energy systems, lubrication, and emerging optoelectronic platforms. By integrating insights from materials chemistry and process engineering, this review outlines clear objective assessment and future opportunities for enabling high-yield, sustainable, and industrially viable production of h-BN nanomaterials.

The growing demand for hydrogen-based energy necessitates the development of high-performance sensors to detect hydrogen leakage in real time for preventing explosion hazards. In this article, we present a high-performance hydrogen-sensing platform based on a porous polydimethylsiloxane (PDMS)-carbon nanotube (CNT) composite decorated with palladium (Pd) nanoparticles using a flashlamp-assisted reduction process. The porous PDMS structure, fabricated using a sacrificial sugar particle template, provides a large specific surface area that enhances the interaction with the hydrogen gas. The Pd@CNT composite significantly improves the sensing performance by enhancing the spillover effect. Unlike the conventional thermal annealing processes for metal particle production, the flashlamp-assisted reduction process allows the rapid and defect-free decoration of Pd nanoparticles onto the CNT-coated porous PDMS support while maintaining the structural integrity of the support. The optimized sensor exhibits rapid response and recovery times (6.7 and 23.3 s, respectively) at 3% hydrogen concentration and retains long-term stability over 100 hydrogen exposure cycles. This approach offers a room-temperature, low-power hydrogen-sensing solution with enhanced durability and efficiency. The developed sensor has significant prospects in wearable chemical sensors and hydrogen safety systems and can inspire the development of more reliable and practical hydrogen detection technologies.

We present a fully porous Ecoflex-based triboelectric nanogenerator (FPE-TENG) engineered for flexible, breathable, and cost-effective self-powered wearable applications. The FPE-TENG employs a unique design composed of entirely porous materials, with porous Ecoflex as the electrification material and porous Ecoflex/carbon nanotubes (CNTs) as the electrode. The fabrication of porous Ecoflex utilizes an innovative methodology that employs a sacrificial brown sugar template, resulting in a highly porous structure that enhances breathability and user comfort for prolonged wearable applications. The FPE-TENG operates in single-electrode mode, generating electrical outputs from human motion with consistent voltage and current over various low frequencies. The FPE-TENG exhibits exceptional mechanical robustness, enduring repeated mechanical deformation and surpassing 12,000 operational cycles without any decrease in electrical performance. The FPE-TENG offers superior moisture dissipation and thermal management capabilities that alleviate common wearability issues, such as sweat accumulation and skin discomfort. Additionally, the real-time demonstration of self-powered sign language interpretation, facilitated by detecting joint movements and generating corresponding electrical signals for text conversion, has been successfully implemented to improve communication for individuals with hearing impairments. With its straightforward fabrication process, cost-effectiveness, mechanical durability, and reliable electrical performance, the FPE-TENG represents a promising solution for future self-powered wearable electronics, energy harvesting, and human-machine interaction systems.

The growing global burden of diabetes necessitates the development of highly sensitive, stable, and cost-effective glucose-sensing technologies. Nonenzymatic electrochemical glucose sensors (NEGS) based on layered double hydroxides (LDHs) provide a durable and tunable alternative to enzymebased sensors. Herein, we report a vanadium-doped nickel-iron LDH (NiFe1-xVx-LDH) system, hydrothermally grown on nickel foam, for enhanced glucose detection. Structural and spectroscopic analyses confirm that optimal vanadium incorporation (x = 0.4) modulates the lattice structure and defect chemistry, forming hierarchical nanoflower-like architectures with enhanced electroactive surface area. These features facilitate enhanced Ni2+/ Ni3+ and V4+/V5+ redox transitions, improving charge transport and glucose oxidation kinetics. The optimized NiFe0.6V0.4-LDH electrode exhibits a high sensitivity of 1.891 mA mM-1 cm-2, a low detection limit of 2.228 & micro;M, and excellent stability. This work highlights the synergistic role of valence-state engineering and defect modulation in designing advanced NEGS platforms, offering promising potential for future electrochemical sensing applications.

Micro-supercapacitors (mSCs) have emerged as next-generation energy storage components suitable for portable, flexible, and eco-friendly electronic device system. In particular, electric double-layer (EDL) mSCs utilizing flexible graphene electrodes have gained significant attention due to their quick and efficient charge/discharge capabilities. Despite significant progress in fabricating mSCs, particularly through the development of laser-induced graphene (LIG) for creating 3D porous electrodes, challenges remain in increasing both energy and power densities. One promising strategy to address these challenges is the incorporation of pseudo-capacitive materials into the 3D graphene structure. However, conventional methods for embedding pseudo-capacitive materials often involve complex and additional labor-intensive steps to the manufacturing process. In this work, we introduce a high-speed mSC fabrication method (< 5 min) that employs a continuous laser-scribing process to directly integrate Mn2O3, a pseudo-capacitive material, onto LIG electrodes, forming hierarchical Mn2O3/LIG structure. By precisely controlling the fabrication parameter, this approach can significantly improve the electrochemical performance by optimizing the density and thickness of Mn2O3, leading to 550.5% increase in capacitance and energy density compared to the LIG electrode. Additionally, the mSCs exhibit outstanding cyclic (> 88% @ 20,000 cycles) and mechanical stability (@ bending radius of 5 mm), confirming their potential for seamless integration into electronic circuits. This innovation not only simplifies the production process of high-performance mSCs but also broadens their potential applications in sustainable and compact electronic device system.

The rising demand for portable, flexible, and eco-friendly electronic devices has spurred the development of micro-supercapacitors (mSCs) as compact and versatile energy storage components. Electric double-layer (EDL)-mSCs incorporating graphene electrodes offer swift and reversible charge/discharge processes, making them suitable for sustainable device systems. To greatly enhance the electrochemical performance of mSCs, we present a direct synthesis and fabrication of surface oxygen vacancy-controlled MnO2 with a Faradaic capacitive behavior on a porous graphene electrode with 3D networked framework. Surface oxygen vacancies in MnO2 were created through hydrogen peroxide (H2O2) treatment, which led to an increase in the electrode's conductivity and facilitating electrochemical reactions due to creation of the local electric field at the vacancy sites. We achieved 251 % and 163 % increase in capacitance of surface oxygen vacancy controlled MnO2/graphene nanocomposite electrode compared to the porous graphene electrode and pristine MnO2/graphene electrode, respectively, and exhibited a volumetric energy density of 3.61 Wh/L. Furthermore, the mSCs demonstrated excellent cyclic stability and mechanical flexibility under various strain conditions. This surface oxygen vacancy-controlled MnO2/graphene nanocomposite electrode represents a simple and efficient strategy for high-performance and versatile energy storage components, with potential applications in electronic devices and sustainable energy systems.

Abstract The increasing demand for miniature, flexible electronic devices have fueled the need for compact and high‐performing energy storage solutions. Microsupercapacitors (mSCs) with reduced dimension and novel electrode design have gained prominence. This concept paper summarizes and views the recent advancements in mSCs with a focus on 3D graphene electrodes and their novel electrode design to increase energy performance of the devices. Especially, we focus on these 3D graphene structures fabricated using a laser‐scribing method which offer an efficient, cost‐effective approach for enhanced mSC performance. Further, this work delves into the vital link between the electrical field effect and geometrically engineered interdigitated electrodes, which is pivotal for maximizing the ion transport and mSC energy storage performance. The insights presented here are promising for meeting the power requirements of future miniature electronics.

In surface-enhanced Raman spectroscopy (SERS), 2D materials are explored as substrates owing to their chemical stability and reproducibility. However, they exhibit lower enhancement factors (EFs) compared to noble metal-based SERS substrates. This study demonstrates the application of ultrathin covellite copper sulfide (CuS) as a cost-effective SERS substrate with a high EF value of 7.2 x 104. The CuS substrate is readily synthesized by sulfurizing a Cu thin film at room temperature, exhibiting a Raman signal enhancement comparable to that of an Au noble metal substrate of similar thickness. Furthermore, computational simulations using the density functional theory are employed and time-resolved photoluminescence measurements are performed to investigate the enhancement mechanisms. The results indicate that polar covalent bonds (CuS) and strong interlayer interactions in the ultrathin CuS substrate increase the probability of charge transfer between the analyte molecules and the CuS surface, thereby producing enhanced SERS signals. The CuS SERS substrate demonstrates the selective detection of various dye molecules, including rhodamine 6G, methylene blue, and safranine O. Furthermore, the simplicity of CuS synthesis facilitates large-scale production of SERS substrates with high spatial uniformity, exhibiting a signal variation of less than 5% on a 4-inch wafer. Large-area and uniform 2D covellite CuS synthesized using a deposited ultrathin Cu film via subsequent room-temperature sulfurization exhibit an anomalous Raman effect owing to charge transfer and dipole-dipole interactions between the analyte molecules and ultrathin 2D CuS.image

Two-dimensional (2D) vertical van der Waals heterostructures (vdWHs) show great potential across various applications. However, synthesizing large-scale structures poses challenges owing to the intricate growth parameters, forming unexpected hybrid film structures. Thus, precision in synthesis and thorough structural analysis are essential aspects. In this study, we successfully synthesized large-scale structured 2D transition metal dichalcogenides (TMDs) via chemical vapor deposition using metal oxide (WO3 and MoO3) thin films and a diluted H2S precursor, individual MoS2, WS2 films and various MoS2/WS2 hybrid films (Type I: MoxW1−xS2 alloy; Type II: MoS2/WS2 vdWH; Type III: MoS2 dots/WS2). Structural analyses, including optical microscopy, Raman spectroscopy, transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy, and cross-sectional imaging revealed that the A1g and E2g modes of WS2 and MoS2 were sensitive to structural variations, enabling hybrid structure differentiation. Type II showed minimal changes in the MoS2′s A1g mode, while Types I and III exhibited a ~2.8 cm−1 blue shift. Furthermore, the A1g mode of WS2 in Type I displayed a 1.4 cm−1 red shift. These variations agreed with the TEM-observed microstructural features, demonstrating strain effects on the MoS2–WS2 interfaces. Our study provides insights into the structural features of diverse hybrid TMD materials, facilitating their differentiation through Raman spectroscopy.

Emerging freestanding membrane technologies, especially using inorganic thermoelectric materials, demonstrate the potential for advanced thermoelectric platforms. However, using rare and toxic elements during material processing must be circumvented. Herein, we present a scalable method for synthesizing highly crystalline CuS membranes for thermoelectric applications. By sulfurizing crystalline Cu, we produce a highly percolated and easily transferable network of submicron CuS rods. The CuS membrane effectively separates thermal and electrical properties to achieve a power factor of 0.50 mW m(-1) K-2 and thermal conductivity of 0.37 W m(-1) K-1 at 650 K (estimated value). This yields a record-high dimensionless figure-of-merit of 0.91 at 650 K (estimated value) for covellite. Moreover, integrating 12 CuS devices into a module resulted in a power generation of similar to 4 mu W at Delta T of 40 K despite using a straightforward configuration with only p-type CuS. Furthermore, based on the temperature-dependent electrical characteristics of CuS, we develop a wearable temperature sensor with antibacterial properties. image

Electrochemical water splitting is promising system for the efficient hydrogen production. Much effort has been devoted to developing cost-effective, catalytically active, and stable electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In this work, we synthesized Co9S8-MoS2 nanohybrid structures derived from CoMo-based bimetallic metal-organic frameworks via a one-pot hydrothermal route followed by sulfurization. Co9S8-MoS2 nanohybrids, composed of small Co9S8-MoS2 core-shell nanospheres covered by large Co9S8/MoS2 nanostructures, are efficient electrocatalysts for both the HER and OER owing to their porous bimetallic structures with large number of surface area and numerous catalytically active sites. The Co9S8-MoS2 nanohybrids show small overpotentials of 110 and 270 mV at 10 mA cm-2 in 1.0 M KOH for the HER and OER, respectively. Furthermore, even after 1000 cycles, the Co9S8-MoS2 nanohybrids exhibited good stability and small Tafel slopes of 59 and 66 mV dec(-1) for both the HER and OER, respectively, demonstrating their potential in practical applications for water splitting. (c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

The mass production of high-quality graphene is required for industrial application as a future electronic material. However, the chemical vapor deposition (CVD) systems previously studied for graphene production face bottlenecks in terms of quality, speed, and reproducibility. Herein, we report a novel conveyor CVD system that enables rapid graphene synthesis using liquid precursors. Pristine and nitrogen-doped graphene samples of a size comparable to a smartphone (15 cm × 5 cm) are successfully synthesized at temperatures of 900, 950, and 1000 °C using butane and pyridine, respectively. Raman spectroscopy allows optimization of the rapid-synthesis conditions to achieve uniformity and high quality. By conducting compositional analysis via X-ray photoelectron spectroscopy as well as electrical characterization, it is confirmed that graphene synthesis and nitrogen doping degree can be adjusted by varying the synthesis conditions. Testing the corresponding graphene samples as gas-sensor channels for NH3 and NO2 and evaluating their response characteristics show that the gas sensors exhibit polar characteristics in terms of gas adsorption and desorption depending on the type of gas, with contrasting characteristics depending on the presence or absence of nitrogen doping; nitrogen-doped graphene exhibits superior gas-sensing sensitivity and response speed compared with pristine graphene.

The pursuit of sub-1-nm field-effect transistor (FET) channels within 3D semiconducting crystals faces challenges due to diminished gate electrostatics and increased charge carrier scattering. 2D semiconductors, exemplified by transition metal dichalcogenides, provide a promising alternative. However, the non-idealities, such as excess low-frequency noise (LFN) in 2D FETs, present substantial hurdles to their realization and commercialization. In this study, ideal LFN characteristics in monolayer MoS2 FETs are attained by engineering the metal-2D semiconductor contact and the subgap density of states (DOS). By probing non-ideal contact resistance effects using CuS and Au electrodes, it is uncovered that excess contact noise in the high drain current (ID) region can be substantially reduced by forming a van der Waals junction with CuS electrodes. Furthermore, thermal annealing effectively mitigates sulfur vacancy-induced subgap density of states (DOS), diminishing excess noise in the low ID region. Through meticulous optimization of metal-2D semiconductor contacts and subgap DOS, alignment of 1/f noise with the pure carrier number fluctuation model is achieved, ultimately achieving the sought-after ideal LFN behavior in monolayer MoS2 FETs. This study underscores the necessity of refining excess noise, heralding improved performance and reliability of 2D electronic devices.

Micro-supercapacitors (mSCs) are crucial components for the miniaturization of electronic devices and the growing demand for portable, wearable, and Internet-of-things (IoT) technology. Among these, electric doublelayer mSCs (EDL mSCs) stand out with their rapid charge/discharge capability and extended lifespan. Porous graphene structure has been utilized to EDL-mSCs due to their compatibility with various substrates and ease of integration. However, methods to increase the performance of the EDL-mSCs based on the porous graphene electrode needs to be considered to achieve high performance flexible mSCs. In this study, we introduce rationally designed, heteroatom doped porous graphene electrodes, incorporating highly electrochemical active nitrogen sites (such as pyrrolic-, pyridinic-, and graphitic-N sites), that greatly enhances the performance of the flexible mSCs. The method involves directly laser scribing polyimide film coated with a phthalocyanine-based dopant, resulting in a remarkable 254 % increase in capacitance and an impressive volumetric energy density of 2.5 mWh cm-3 compared pristine EDL-mSC. This heteroatom-doping strategy improves conductivity and surface wettability and creates more active sites for specific capacitance. Additionally, the heteroatom-doped mSCs exhibit excellent capacitance retention under strain and bending tests, demonstrating their suitability for practical circuit applications. This work offers a simple and effective approach to design flexible and highperformance mSCs, meeting the energy-storage demands of modern electronics and IoT devices.

Transition-metal sulfides are emerging as promising materials for chemiresistive gas sensors─a field still dominated by semiconducting metal oxides. Despite the availability of materials with tunable electronic, optical, physical, and chemical properties, few studies have moved beyond synthesis to provide strategies for enhancing gas sensing performance through material modification. Here, we present a simple, scalable synthetic strategy for developing an optically semitransparent, flexible NH3 gas sensor with a highly uniform, ultrathin CuS (covellite) active sensing layer. The optical and chemical properties of the CuS were precisely controlled near the percolation threshold of thin-film formation by varying key experimental parameters such as the Cu film thickness (<10 nm) and the sulfurization time (∼90 s) under ambient conditions. Experimental and computational studies of CuS and its NH3 sensing characteristics identify key physicochemical properties. The controlled surface chemistry and morphology of the ultrathin CuS layer demonstrate its effectiveness in functional NH3 sensing devices, which achieve a calculated detection limit of 1.38 ppm for NH3 gas at 150 °C, along with exceptional mechanical robustness and optical semitransparency in the visible-light spectrum.

In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable platform. To implement the micro-supercapacitors in various practical applications that can accompany solid state or gel electrolyte and flexible substrates, ions must be readily transported to electrodes for achieving high power densities. Herein, we show large enhancement in electrochemical properties of flexible, in-plane micro-supercapacitor using sharp-edged interdigitated electrode design, which was simply fabricated through direct laser scribing method. The sharp-edged electrodes allowed strong electric field to be induced at the corners of the electrode fingers which led to the greater accumulation of ions near the surface of electrode, significantly enhancing the energy storage performance of micro-supercapacitors. The electric field-enhanced in-plane micro-supercapacitor showed the volumetric energy density of 1.52 Wh L-1 and the excellent cyclability with capacitive retention of 95.4% after 20 000 cycles. We further showed various practicability of our sharp-edged design in micro-supercapacitors by showing circuit applicability, mechanical stability, and air stability. These results present an important pathway for designing electrodes in various energy storage devices.

Improving the capacitance and energy density is a significant challenge while developing practical and flexible energy storage system (ESS). Redox mediators (RMs), as redox-active electrolyte additives, can provide additional energy storing capability via electrochemical faradaic contribution on electrodes for high-performance flexible ESSs. Particularly, determining effective material combinations between electrodes and RMs is essential for maximizing surface faradaic redox reactions for energy-storage performance. In this study, an electrode-RM system comprising heterostructured hybrid (carbon fiber (CF)/ MnO2) faradaic electrodes and iodine RMs (I-RMs) in a redox-active electrolyte is investigated. The CF/ MnO2 with the I-RMs (CF/MnO2-I) induces dominant catalytic faradaic interaction with the I-RMs, significantly enhancing the surface faradaic kinetics and increasing the overall energy-storage performance. The CF/MnO2-I ESSs show a 12.6-fold (or higher) increased volumetric energy density of 793.81 mWh L-1 at a current of 10 lA relative to ESSs using CF/MnO2 without I-RMs (CF/MnO2). Moreover, the CF/ MnO2-I retains 93.1% of its initial capacitance after 10,000 cycles, validating the excellent cyclability. Finally, the flexibility of the ESSs is tested at different bending angles (180 & DEG; to 0 & DEG;), demonstrating its feasibility for flexible and high-wear environments. Therefore, CF/MnO2 electrodes present a practical material combination for high-performance flexible energy-storage devices owing to the catalytic faradaic interaction with I-RMs.& COPY; 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.