Fuel adulteration remains a significant concern because it can reduce engine performance, shorten the service life of engines and machinery, and increase harmful emissions when lower-cost hydrocarbons, such as kerosene, are added to commercial fuels. These issues result in financial losses and environmental hazards, underscoring the need for rapid and precise detection techniques. To solve these issues, we propose a novel sensor that allows fuel quality monitoring by utilizing the principles of surface plasmon resonance (SPR) to identify minute variations in the refractive index at a constant wavelength of 633 nm. The present work reports the use of a multilayer structure, including a BAK1 prism, silver (Ag), hafnium dioxide (HfO2), aluminium antimonide (AlSb), and iron sesquioxide (FeO3), to detect fuel adulteration based on the change in refractive index (RI). The performance of the sensor was calculated using key parameters, such as sensitivity, Quality factor (QF), signal-to-noise ratio (SNR), figure of merit (FOM), and combined sensitivity factor (CSF). The results obtained from the proposed sensor having sensitivity of 389.91 °/RIU, a QF of 201.193 RIU−1, a SNR of 0.231, a FOM of 114.481, and CSF of 109.4. This results in the possibility of the accurate detection of fuel adulteration. Graphene, Black phosphorous (BP), Molybdenum Disulfide (MoS2) and molybdenum Di selenide ( MoSe2) are the 2D materials improved the performance of the sensor. The proposed biosensor offers an affordable, quick, and field-deployable fuel quality solution to address the serious environmental and life span issues of machines related to fuel adulteration.
Biosensor performance depends strongly on the properties of the functionalized electrode interface, making robust and controllable surface modification strategies highly desirable. In this work, we investigate electrochemical click chemistry (E-click) as an electrochemically driven route for the functionalization of sensor-relevant electrode surfaces. Using an azide-tagged fluorophore as receptor model, we demonstrate controllable surface functionalization via in situ electrochemical generation of the catalytic species. Surface modification was characterized by X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and contact angle measurements, confirming successful interfacial functionalization. The influence of reaction time and applied potential on the efficiency of the E-click process was systematically examined, highlighting the importance of operating conditions that promote effective catalyst generation and surface coupling. In addition, we showed that E-click can be performed using an atomic force microscopy cantilever as the working electrode, offering a potential solution for localized micro- and nanoscale patterning with utility in preparation of multiplexed sensing interfaces. These results establish E-click as a versatile electrochemical approach for controlled electrode surface modification. Electrochemical click functionalization using Cu(I) catalyzed azide-alkyne cycloaddition of a model biosensor surface. Evolution of surface functionalization studied with X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and contact angle measurements. Optimal functionalization parameters and time dependence demonstrated. Localized patterning approach with conductive AFM tip for potential multiplexed sensors.
Abstract Overactive Bladder (OAB) is a condition known by the symptoms like urgency and increased frequency of urination. About 17% of adults are affected in US alone. Oxybutynin hydrochloride (OBH) is used as vital antimuscarinic agent against this condition. The drug fights the pathogens that may be causing the condition and provides relief to the affected. In this study, a highly sensitive electrochemical sensor was developed based on a glassy carbon electrode (GCE) for the detection of OBH. A well know conducting polymer, polyaniline (PANI) was used as a modifier to enhance the detection limit (D L ) of the GCE for OBH. The morphological and elemental composition studies were carried out by using Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDX) and X-ray Diffraction (XRD), which confirmed the successful synthesis of PANI. The modifier, other than being a great surface area enhancer, also acted as potent electrocatalytic framework that catalyzed the oxidation of OBH. The cyclic voltammetry (CV) studies under the potential range of 0.5–1.5 V at a pH of 7.4 and immersion time of 40 s, established that the electrochemical oxidation of OBH was irreversible and diffusion controlled. The studies also revealed that the mechanism involved a two electron and two proton involvement. Square-wave voltammetry (SWV) studies determined the sensitivity of the PANI/GCE in terms of detection limit which was 9.16 nM. The sensor also exhibited high recovery rate in pharmaceutical solutions and biological fluids, showing its potential in being a high precision tool for quality control and pharmacokinetic analysis.
Biochar (BC), a stable, carbon-rich material produced by heating biomass, is increasingly used in electrochemical sensing, particularly in hybrid nanocomposite forms, because hybridization can improve electrical conductivity, catalytic activity, surface area, and interfacial charge-transfer characteristics, making it well-suited as advanced functional sensing materials. In particular, their nanoarchitecture and functionality can be precisely controlled during synthesis to meet specific sensing requirements, including selective target interactions, elemental composition, and nanoscale dimensions, thereby demonstrating their versatility as next-generation sensing materials. Unlike previous reviews that focus on synthesis and general applications, this review summarizes recent advances in BC-based nanohybrids for electrochemical sensing, covering their synthesis methods, nanoarchitectures, and functions, with a particular focus on those incorporating graphene, carbon nanotubes, graphite, polymers, metal–organic frameworks, and noble metals. The roles of these materials in improving the detection efficiency of environmental contaminants, including toxic metals, pesticides, agrochemicals, pharmaceuticals, organics, and emerging pollutants, are discussed, along with their detection limits and dynamic ranges. The review also provides electrode surface modification strategies to produce effective electrode films and highlights the potential for developing a conductive, low-cost BC-based ink as an alternative to commercial graphene ink. Future perspectives address the need for sustainable synthesis strategies and the integration of computational chemistry to design practical BC nanohybrid systems for smart, eco-friendly electrochemical sensing applications. Also, we highlight the emergence of environmental contaminants and the challenges they pose, emphasizing the need for stronger action to address these serious concerns.
Activated carbon (AC) was synthesized from Bauhinia variegata flowers through chemical activation, followed by manganese incorporation using a sonochemical impregnation approach. The electrochemical and photovoltaic performances of pristine AC and Mn-doped activated carbon (Mn–AC) were systematically investigated for electrochemical double-layer capacitor (EDLC) and dye-sensitized solar cell (DSSC) applications. The effect of manganese doping on the capacitive behavior, charge-transfer characteristics, and interfacial kinetics of the activated carbon electrodes was examined. The results show that the specific capacitance of activated carbon is enhanced after Mn incorporation due to improved surface polarity, electrolyte wettability, and additional fast surface redox contributions. The optimized Mn–AC electrode exhibits a specific capacitance of 20 F g−1 at low frequency and demonstrates stable electrochemical behavior. Furthermore, Mn–AC counter electrodes deliver a nearly twofold improvement in DSSC power conversion efficiency compared to pristine AC, indicating improved electrocatalytic activity. These results demonstrate that sonochemically Mn-doped biomass-derived activated carbon is a promising multifunctional electrode material for energy storage and conversion devices.
Developing environmentally friendly and high-performing solid polymer electrolytes (SPEs) is crucial for advancing sustainable energy storage technologies. In this work, biodegradable corn starch (CS) is used as the polymer matrix to prepare SPEs via solution casting. Lithium perchlorate (LiClO4) serves as the lithium-ion source, Pluronic (a triblock copolymer of PEG and PPG) as a plasticizer, and graphene oxide (GO) as a nanofiller. The effects of salt, plasticizer, and filler content on structural, thermal, and electrochemical properties are systematically investigated. FTIR spectroscopy reveals progressive disruption of starch crystalline order upon addition of LiClO4, Pluronic, and GO, with the order parameter R993/1015 decreasing from 1.24 (neat CS) to 0.65 (optimized composite). Differential scanning calorimetry indicates that the onset decomposition temperature remains above 230 °C for all samples, sufficient for practical applications. Electrochemical impedance spectroscopy (EIS) demonstrates that the optimized composition (CS/20 wt
Recent advancements in two-dimensional (2D) materials have focused on MXenes as candidate materials for future energy storage and water splitting devices owing to their outstanding electrical conductivity, hydrophilicity, tunable surface chemistry, large specific surface area, and excellent electrochemical activity. This review is devoted to summarizing a comprehensive overview of the latest developments in MXene-based materials for high-performance supercapacitors and electrocatalytic water splitting. The synthesis strategy, structural characteristics, surface functionalization approaches, and the composite formation technique are critically discussed to establish the influence of the electrochemical performance. Particular emphasis is placed on the role of MXene in promoting charge transfer, accelerating the ion diffusion, and enhancing electrochemical kinetics, leading to superior capacitance, rate capability, cyclic stability, and highly efficient HER, OER, and overall water splitting performance. This review also critically examines the major challenges limiting practical implementation, including oxidation instability, nanosheet restacking, limited large-scale synthesis, and long-term durability. Finally, the future research perspectives are proposed, focusing on scalable synthesis and surface interface engineering, defect and heterostructure engineering, and device integration to accelerate the development of efficient, stable, commercially viable MXene-based materials for sustainable energy storage and hydrogen production. By systematically correlating material design with electrochemical performance, this review provides valuable insight and practical guidelines for the rational development of advanced MXene-based energy storage and water splitting systems.
Melatonin (N-acetyl-5-methoxytryptamine) is a neurohormone predominantly synthesized in the pineal gland and widely known for its role in circadian rhythm regulation. Beyond its chronobiological function, melatonin exhibits potent antioxidant and cytoprotective activities, and reduced endogenous levels have been associated with the progression of several neurodegenerative disorders. These factors highlight the need for rapid and accurate analytical strategies for the detection of melatonin in complex biological matrices. In this study, we developed an immunosensor for proof-of-concept sensing in complex biological matrices (kidney, heart, and liver) of Wistar rats. Tissues from treated and control groups were spiked with a commercial melatonin standard and analyzed using the proposed platform. The gold electrode was functionalized with an anti-melatonin antibody to form a sensing interface. The sensor was characterized by Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), and Square Wave Voltammetry (SWV). The platform exhibited a limit of detection (LOD) of 4 µM, a limit of quantification (LOQ) of 14 µM, and a sensitivity of 250 µA µM−1 cm−2. The detectable melatonin levels in the evaluated tissues are likely influenced by the matrix complexity. These findings demonstrate the potential of the Au/SAM-MUA/anti-ME immunosensor as a proof-of-concept tool for the monitoring of melatonin-associated responses in tissue homogenates.
Herein, three representative silicon-based anode materials, namely pure nano-silicon (Si), ball-milled silicon/carbon composite (BM Si/C), and chemical vapor deposition silicon/carbon composite (CVD Si@C), were systematically investigated for their application in all-solid-state lithium batteries. X-ray diffraction and Raman spectroscopy analyses confirmed that BM Si/C maintained the crystalline structure of silicon with a defect-rich carbon network, while CVD Si@C exhibited an amorphous silicon phase uniformly distributed within porous carbon frameworks with Si–C covalent bonding. The initial reversible capacities for Si, BM Si/C and CVD Si@C were 2810.4, 1230.1 and 1648.2 mAh g− 1, with Coulombic efficiencies of 65.97, 62.81 and 72.94
Platinum nanowires (PtNWs), with lengths on the micrometer scale and diameters of approximately 5–10 nm, were successfully synthesized on a TiO2-C composite support using a hydrothermal method. This method involved a reaction system comprising dimethylformamide (DMF), KOH, TiO2, acetylene black (BP2000), ethylene glycol, and HPtCl6·6H2O. X-ray diffraction (XRD) revealed that the surface of the nanowires is predominantly composed of (111) and (200) crystal planes, corresponding to their most intense diffraction peaks. Accelerated degradation tests (ADT) demonstrated that the Pt/TiO2−C catalyst exhibits significantly higher structural stability compared to commercial Pt/C, a phenomenon attributed to the robust interaction between the TiO2 anchoring sites dispersed within the continuous carbon phase and the Pt nanowires. Although the electrochemically active surface area of Pt/TiO2–C is only about one-third that of commercial Pt/C, its mass activity and specific activity are two times and six times greater than those of commercial Pt/C, respectively. In the cathode of an aluminum-air battery, which simulates a triple-phase (gas–liquid-solid) mass transfer environment, the cell loaded with Pt/TiO2-C exhibited slower voltage decay during galvanostatic discharge at 50 mA cm−2, indicating improved durability. However, polarization curve results also indicate that at current densities exceeding 111 mA cm−2, the discharge voltage of aluminum-air batteries utilizing a Pt/TiO2–C cathode is lower than that of commercial Pt/C. Therefore, while the PtNWs provide high stability due to their chain-like structure, their aspect ratio requires further optimization to mitigate the oxygen reduction reaction (ORR) mass transfer issues arising from the significant curling and entanglement of the nanowires.
Electrochemical generation of sodium hypochlorite (NaOCl) from sodium chloride (NaCl) solutions provides a practical route for on-site disinfectant production in water treatment systems. However, meaningful comparison among electrode materials remains challenging because many studies employ different reactor configurations and operating conditions. In this work, five accessible non-dimensionally stable anode (non-DSA) materials, aluminum (Al), copper (Cu), graphite, stainless steel (SS), and platinum (Pt), were evaluated under identical electrolysis conditions in an undivided, stirred batch cell containing 20 g L−1 NaCl at near-neutral pH. Electrode spacing (4–10 cm) and applied voltage (6–12 V) were systematically varied, and free chlorine accumulation was quantified by iodometric titration over 40 min. Reducing the electrode spacing from 10 to 8 cm increased free chlorine formation by reducing ohmic losses and improving current delivery. Graphite produced the highest free chlorine concentrations and Faradaic efficiencies, whereas aluminum and copper showed lower net accumulation due to electrode instability and catalytic hypochlorite decomposition. Platinum sustained the highest current densities but comparatively low Faradaic efficiencies, indicating that increasing current alone does not guarantee higher net free chlorine accumulation under near-neutral conditions. These results provide a controlled benchmarking dataset for evaluating low-cost electrode materials in decentralized electrochlorination systems.
Abstract Contamination of heavy metals in environmental matrices such as water and soil poses a severe threat to public health due to the persistence, bioaccumulation, and most major toxic metals that concerns the public safety are lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg). These toxic chemicals are non-biodegradable and can pollute the food chain, bioaccumulate in biological tissues and cause neurological diseases, renal damage, cardiovascular disease, developmental abnormalities and different malignancies, particularly in sensitive populations such as children and pregnant women. Heavy metals are non-biodegradable and may stay in ecosystems for decades. They constitute considerable concern to the environment and human health even at low concentrations because of long-term exposure. Consequently, monitoring heavy metal contamination has become a global priority in the environmental systems. Regulation agencies like the WHO and EPA require detection at sub-ppb levels, demanding very sensitive and selective analytical techniques. Although the conventional techniques like induced coupled plasma mass spectroscopy (ICP-MS) and atomic absorption spectroscopy (AAS) provide excellent sensitivity, their high cost, complex instruments, and limited portability restrict their usage in the onsite settings. Voltametric electrochemical methods, especially stripping techniques such as anodic stripping voltammetry (ASV), square wave anodic stripping voltammetry (SWASV), and differential pulse voltammetry (DPV), have emerged as powerful, cost-effective, and portable alternatives capable enough to achieve sub-ppb LOD through the preconcentration strategy. Recent progress in electrochemical sensing has been focused on nanomaterial-modified electrodes based on graphene, metal oxides, bismuth films, metal nanoparticles and hybrid nanocomposites which greatly boost the sensitivity, selectivity, conductivity and surface area. Moreover, the integration of electrochemical sensors with flexible electronics, microfluidic systems, wireless communication modules, and smartphone-based platforms has encouraged the development of wearable and portable sensing technologies for environmental monitoring. Emerging wearable sensors, paper-based analytical devices, and handheld electrochemical systems facilitate rapid onsite measurements, real-time data transmission, and decentralized monitoring of heavy metal contamination in drinking water, industrial wastewater, agricultural runoff, and other environmental matrices. This review mainly focuses on the examination of the fundamental principles of voltametric detection, major voltametric stripping techniques, and advanced pulse methods with special emphasis on nanomaterial-modified electrodes incorporating graphene, metal oxides, bismuth films, and hybrid nanocomposites that enhance sensitivity and selectivity significantly. Detection of the particular heavy metals is discussed alongside key analytical performance parameters, interference challenges, and real sample validation in drinking water, and industrial wastewater.
The significance of nanocomposites (NCs) in the academic and industrial fields has been of great focus due to the combination of various qualities of different nanomaterials, with the aim of achieving controlled properties. In this work, the aptasensor fabrication consists of a SARS-CoV-2 spike glycoprotein specific thiolated aptamer (HS-Apt) immobilised on a surface of polyaniline (PANI) and 3-mercaptopropionic acid capped gadolinium telluride selenide quantum dots (3-MPA-GdTeSe) functionalised on a glassy carbon electrode (GCE). The interaction between the amine function of PANI and the carboxylic acid ligand of 3-MPA-GdTeSe was confirmed using Fourier transform infrared (FTIR) and Raman. Parameters such as pH, scan rate, and aptamer incubation of the aptasensor were optimized using cyclic voltammetry (CV). The latter parameter achieved an optimum electrochemical performance after 7 min (min) of aptamer incubation. The response of the aptasensor to a wide range concentration of SARS-CoV-2 spike glycoprotein (0–0.95 fM) was analysed using square wave voltammetry (SWV) and a linear response was observed in 0.1 M PBS during triplicate analysis. Furthermore, obtaining respective limits of detection and quantification of 0.04 and 0.4 fM. The fabricated aptasensor possessed good stability at room temperature and at 4 °C, retaining respective 74 and 75
Abstract This study demonstrates the direct use of crude aqueous cagaita (Eugenia dysenterica) extract as a green corrosion inhibitor for AISI 1020 carbon steel in 10 wt% HCl. Unlike many plant-based inhibitors that require organic solvents, purification, or chemical modification, the proposed approach uses the raw extract directly, highlighting a simple, low-cost, and sustainable route for corrosion protection. Electrochemical measurements showed that the extract strongly reduced the corrosion rate, reaching an inhibition efficiency of approximately 92% at 0.3 g L⁻¹. The small shift in corrosion potential and the simultaneous decrease in anodic and cathodic currents indicate mixed-type inhibition, mainly controlled by adsorption on the steel surface. This behavior is attributed to phenolic compounds naturally present in the extract, especially epicatechin and quercetin, which can interact with the metal surface through hydroxyl groups and aromatic π-electron systems. Surface analyses confirmed reduced steel degradation and lower formation of corrosion products in the inhibited medium. These results show that crude cagaita extract can be applied directly as an effective, renewable, and environmentally friendly inhibitor for carbon steel protection in acidic industrial environments.
Proton exchange membrane water electrolysis is a promising technology for sustainable hydrogen production yet transferable diagnostics across systems, especially in early operation remain as a key challenge for a reproducible operation. Despite being an easily accessible metric, transient open circuit voltage behavior in proton exchange membrane water electrolysis remains less explored than in proton exchange membrane fuel cells. In this work, early post conditioning open circuit voltage behavior is evaluated as an empirical indicator of transient instability during operation. The results reveal clear differences between open circuit voltage behavior and subsequent operational performance for catalyst coated membranes incorporating nominally identical membranes from different manufacturers. These findings highlight the potential of simple diagnostic strategies for early-stage material assessment in proton exchange membrane water electrolysis, suggesting differences in manufacturing while exposing limitations in the reproducibility of the metric across nominally identical material and operational conditions. Additionally, material properties were investigated after conditioning step, using fluoride ion and total fluorine measurements as two closely related metrics and their potential link to open circuit voltage performance. No clear correlation between these metrics and open circuit voltage behavior was observed.
This study demonstrates the direct use of crude aqueous cagaita (Eugenia dysenterica) extract as a green corrosion inhibitor for AISI 1020 carbon steel in 10 wt
This study presents the synthesis and evaluation of CuCo2O4 and CuCo2O4/activated carbon (AC) composites as electrode materials for supercapacitors. X-ray diffraction confirmed the cubic spinel phase, with crystallite size reduced from 43.89 nm in pristine CuCo2O4 to 33.79 nm in the composite. Incorporation of AC significantly enhanced the surface area from 20 m2/g to 562 m2/g and reduced pore size to 1.9 nm, enabling efficient ion transport. Electrochemical studies revealed a specific capacitance of 643.75 F g−1 for CuCo2O4/AC, notably higher than 389.06 F g−1 for pristine CuCo2O4 at 1 A g−1. Dunn analysis showed capacitive charge storage contributions of 55–82
Liquid crystal (LC)-based biosensors have emerged as an attractive biosensor due to their high sensitivity to interfacial molecular interactions and their capability for label-free detection. This review summarizes recent advancements and emerging trends in LC-based biosensing platforms. The fundamental properties of LC materials, such as orientation-dependent optical behavior and interfacial responsiveness, are discussed in connection with recent advances in LC-based sensing strategies for biological and chemical detection. To facilitate real-world diagnostic applications using LC biosensors, existing challenges and future perspectives for the development of reliable and portable LC biosensing systems are also addressed. This review presents a systematic discussion of (a) the unique characteristics of LC enabled biosensors, (b) the classification of LC biosensors based on device geometry, (c) sensing mechanisms in planar, cholesteric liquid crystal (CLC), emulsion and electrochemical LC-based, (d) conventional and emerging LC biosensing configurations, including planar films, LC-aqueous interfaces, CLC systems, and emulsion-based platforms, (e) molecular recognition strategies for biomolecule detection, and (f) recent challenges and future directions. Overall, this review aims to provide a comprehensive resource for researchers and engineers working in the interdisciplinary field of LC-based biosensing and highlight the potential of LC platforms for next-generation diagnostic technologies.
The development of nanostructured materials and improved capability of controlling the size dependent properties in the previous two decades have offered extensive application for energy storage applications. This review highlights the benefits provided by nanomaterials for capacitors using (i) carbon based materials for high surface area, (ii) conducting polymers as low cost, high charge density, easily processable, electroactive pseudocapacitive material and (iii) metal oxides for pseudocapacitance effect. Further it covers the use silicon based nanomaterials, flexible electrodes and controlling the unstable solid-electrolyte interphase (SEI) for efficient energy storage in lithium batteries. Applications of some important modern nanomaterials like MXenes, borophene, phosphorene, janus nanosheets, Ti3C2 and metal organic framework (MOF) derived nanostructures for energy storage is also briefly discussed.
We report on the microwave aided activation of activated carbon (AC) prepared from aerobic combustion of cotton in sesamee oil. It has been revealed that microwave aided activation at 110 °C in convection mode for 5 min improve the porosity and surface area of prepared AC. The produced AC exhibited the surface area of 686 m2/g with total pore volume of 0.44 cm3/g which is higher than bare carbon without activation (surface area of 92.5 m2/g and total pore volume of 0.13 cm3/g). Therefore, the prepared AC-based device exhibited an impressive energy density of 33.68 Wh/kg with specific capacitance of 485 F/g at 1 A/g. In addition, the series combination of three devices demonstrated the stable operation up to 3 V and glow the red LED for 65 s. These results exhibiting that microwave assisted activation method could be beneficial in terms of ease of process and time/energy saving in compare to the conventional activation process at high temperature to produced high quality carbon materials for supercapacitor applications.
