Search Results (400)

In this study, we investigate the electrochemical performance of a carboxyl-functionalized pencil graphite (CFPG) electrode for chloride ion oxidation and its subsequent application in dye degradation. The graphite electrode was chemically modified using acetic acid to introduce –COOH functional groups, enhancing surface polarity and chloride adsorption capacity. Surface characterization by SEM, EDX, and XPS confirmed morphological changes and oxygen enrichment following functionalization. Electrochemical measurements demonstrated a positive shift in open circuit potential (OCP) and significantly enhanced chloride oxidation activity, as evidenced by cyclic voltammetry (CV) in 0.1 M KCl. The functionalized electrode facilitated the in situ generation of reactive chlorine species (RCS), with spectral features near ~240 nm consistent with HOCl/ClO⁻ and a broader band around ~450 nm attributable to chlorine-derived intermediates rather than exclusively to molecular chlorine. These species played a central role in degrading structurally diverse dyes—Kenacid Green and Brilliant Green—via oxidative pathways. The results highlight the potential of low-cost, –COOH-modified graphite electrodes as effective platforms for the RCS-mediated electrochemical treatment of organic contaminants. Full article

The development of bio-derived composites represents a sustainable and cost-effective strategy for advanced energy storage applications. In this work, a porous carbon/nickel oxide (NiO) composite was synthesized from orange peel via carbonization at 500 °C followed by KOH activation at 700 °C and subsequent hydrothermal NiO modification. The resulting material exhibited a hierarchical porous structure with a high specific surface area (2120 m² g⁻¹ for OP_500_700 and 1968 m² g⁻¹ for NiO-modified OP_500_700_0.1M), with both values being significantly higher than that of the non-activated OP_500 (3.40–18.12 m² g⁻¹). Electrochemical evaluation revealed that the NiO-functionalized composite achieved a specific capacitance of 306.0 F g⁻¹ at 5 mV s⁻¹ and 281.5 F g⁻¹ at 2 A g⁻¹, surpassing the pristine activated carbon (281.9 F g⁻¹ and 259.6 F g⁻¹, respectively). In addition, both electrodes demonstrated excellent cycling stability, retaining more than 80% capacitance after 5000 charge–discharge cycles at a high current density of 20 A g⁻¹, while the NiO-modified electrode further benefited from a self-activation effect leading to >100% retention. These findings emphasize the synergistic effects of hierarchical porosity and NiO pseudocapacitance, establishing orange peel-derived carbon/NiO composites as scalable and sustainable electrode materials for next-generation supercapacitors. Full article

Herein, we propose an ultrasensitive electrochemical immunosensor based on glucose oxidase labeling and enzyme-catalyzed Au staining. In brief, the primary antibody (Ab₁), bovine serum albumin, an antigen and then a bionanocomposite that contains a second antibody (Ab₂), poly(3-anilineboronic acid) (PABA), Au nanoparticles (AuNPs) and glucose oxidase (GOx) are modified on a glassy carbon electrode coated with multiwalled carbon nanotubes, yielding a corresponding sandwich-type immunoelectrode. In the presence of glucose, a chemical reduction of NaAuCl₄ by enzymatically generated H₂O₂ can precipitate a lot of gold on the Ab₂-PABA-AuNPs-GOx immobilized immunoelectrode. In situ anodic stripping voltammetry (ASV) detection of gold in 8 μL 1.0 M aqueous HBr-Br₂ is conducted for the antigen assay, and the ASV detection process takes approximately 6 min. This method is employed for the assay of human immunoglobulin G (IgG) and human carbohydrate antigen 125 (CA125), which demonstrates exceptional sensitivity, high selectivity and fewer required reagents/samples. The achieved limits of detection (S/N = 3) by the method are 0.25 fg mL⁻¹ for IgG (approximately equivalent to containing 1 IgG molecule in the 1 microlitre of the analytical solution) and 0.1 nU mL⁻¹ for CA125, which outperforms many previously reported results. Full article

SPCEs are crucial for electrochemical sensing because of their portability, low cost, disposability, and ease of mass production. This study details their manufacture, surface modifications, electrochemical characterization, and use in chemical and biosensing. SPCEs integrate working, reference, and counter electrodes on PVC or polyester substrates for compact sensor design. Surface modifications, such as plasma treatment (O₂, Ar), nanomaterial addition (AuNPs, GO, CNTs), polymer coatings, and MIPs, enhance performance. These changes improve sensitivity, selectivity, stability, and electron transport. Electrochemical methods such as CV, DPV, SWV, and EIS detect analytes, including biomolecules (glucose, dopamine, and pathogens) and heavy metals (Pb²⁺, As³⁺). Their applications include healthcare diagnostics, environmental monitoring, and food safety. Modified SPCEs enable rapid on-site analysis and offer strong potential to transform our understanding of the physical world. Full article

Bisphenol A (2,2-bis(4-hydroxyphenyl)propane, BPA), an endocrine-disrupting chemical with recognized adverse effects on human health and ecosystems, urgently requires convenient, sensitive, and accurate detection methods. In this study, a hierarchical heterostructure was fabricated by incorporating Ti₃C₂T_x MXene and mesoporous hollow carbon spheres (MHCs) to develop a high-performance electrochemical sensor for BPA. The nanocomposite was thoroughly characterized using SEM, TEM, and XRD, and then applied to modify a glassy carbon electrode (GCE). Under optimized conditions including pH and accumulation time, BPA detection was carried out via differential pulse voltammetry (DPV). The sensor exhibited a wide linear detection range from 10 to 200 μM and a low detection limit of 2.6 μM. Moreover, it was successfully applied to environmental water samples, demonstrating high accuracy and practicality for real-world BPA monitoring. Full article

A compact electrochemical sensor module for pH detection was developed for potential integration into specialized devices used for live cell or tissue incubation, for applications in highly parallelized cell culture analysis, by incorporating Organ-on-Chip devices. This research focuses on the deposition, structural and chemical analysis, and functional characterization of different titanium-oxide layers with various compositions as potentially sensitive materials for pH sensing applications. The titanium-oxide layers were deposited using vacuum sputtering and atomic layer deposition at 100 °C and 300 °C, respectively. Transmission electron microscopy and X-ray photoelectron spectroscopy were utilized to determine the specific composition and structure of different titanium-oxide layers. These TiO_x-functionalized electrodes were connected to the application-specific analog front-end chip of the low-power readout circuit for precise evaluation. The pH sensitivity of the differently modified electrodes, employing various TiO_x materials, was evaluated using pH calibration solutions ranging from pH 6 to 8. Among the various deposition solutions, such as sputtering or high-temperature atomic layer deposition, the TiO_x layer deposited using low-temperature atomic layer deposition proved more suitable for pH sensing applications, with a sensitivity of 54.8–56.7 mV/pH, which closely approximates the Nernstian response. Full article

Thallium is a soft metal with a grey or silvery hue. It commonly occurs in two oxidation states in chemical compounds: Tl⁺ and Tl³⁺. Thermodynamically, Tl⁺ is significantly more stable and typically represents the dominant form of thallium in environmental systems. However, in this chemical form, thallium remains highly toxic. This study focuses on the modification of a glassy carbon electrode (GCE) with silver nanostructures stabilised by potato starch derivatives. The modified electrode (GCE/AgNPs-E1451) was used for the determination of trace amounts of thallium ions using anodic stripping voltammetry. Emphasis was placed on assessing the effect of surface modification on key electrochemical performance parameters of the electrode. Measurements were carried out in a base electrolyte (EDTA) and in a real soil sample collected from Bali. The stripping peak current of thallium exhibited linearity over the concentration range from 19 to 410 ppb (9.31 × 10⁻⁸ to 2.009 × 10⁻⁶ mol/dm³). The calculated limit of detection (LOD) was 18.8 ppb (9.21 × 10⁻⁸ mol/dm³), while the limit of quantification (LOQ), corresponded to 56.4 ppb (2.76 × 10⁻⁷ mol/dm³). The GCE/AgNPs-E1451 electrode demonstrates several significant advantages, including a wide detection range, reduced analysis time due to the elimination of time-consuming pre-concentration steps, and non-toxic operation compared to mercury-based electrodes. Full article

This work introduces 2-(azulen-1-yldiazenyl)-5-(thiophen-2-yl)-1,3,4-thiadiazole (L) as a functional monomer capable of forming stable, redox-active films with high affinity for lead in aqueous solutions. L was synthesized and characterized using physical chemical methods and electrochemistry. Polymer films of L were prepared through oxidative electro polymerization on glassy carbon electrodes in L solutions in 0.1 M TBAP in acetonitrile. They were characterized through electrochemistry. The surface of chemically modified electrodes (CMEs) prepared through controlled potential electrolysis (CPE) at variable concentrations, potentials, and electric charges was characterized through scanning electron spectroscopy, atomic force microscopy, and Raman spectroscopy, which confirmed the films’ formation. Electrochemical sensing of the films deposited on these CMEs was tested with respect to heavy metal (HM) ion analysis in aqueous solutions to obtain sensors for HMs. The obtained CMEs presented the best characteristics for the recognition of Pb among the investigated HMs (Cd, Pb, Cu, and Hg). Calibration curves were obtained for the analysis of Pb(II) in aqueous solutions, which allowed for the estimation of a good detection limit of this cation (<10⁻⁸ M) for non-optimized CMEs. The resulting CMEs show promise for deployment in portable environmental monitoring systems, with implications for public health protection and environmental safety. Full article

Precision and real-time detection of hydrogen peroxide (H₂O₂) are essential in pharmaceutical, industrial, and defence sectors due to its strong oxidizing nature. In this study, silver (Ag)-doped CeO₂/Ag₂O-modified glassy carbon electrode (Ag-CeO₂/Ag₂O/GCE) has been developed as a non-enzymatic electrochemical sensor for the sensitive and selective detection of H₂O₂. The synthesized Ag-doped CeO₂/Ag₂O nanocomposite was characterized using various advanced techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). Their optical, magnetic, thermal, and chemical properties were further analyzed using UV–vis spectroscopy, electron paramagnetic resonance (EPR), thermogravimetric-differential thermal analysis (TG-DTA), and X-ray photoelectron spectroscopy (XPS). Electrochemical sensing performance was evaluated using cyclic voltammetry and amperometry. The Ag-CeO₂/Ag₂O/GCE exhibited superior electrocatalytic activity for H₂O₂, attributed to the increased number of active sites and enhanced electron transfer. The sensor displayed a high sensitivity of 2.728 µA cm⁻² µM⁻¹, significantly outperforming the undoped CeO₂/GCE (0.0404 µA cm⁻² µM⁻¹). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 6.34 µM and 21.1 µM, respectively, within a broad linear detection range of 1 × 10⁻⁸ to 0.5 × 10⁻³ M. The sensor also demonstrated excellent selectivity with minimal interference from common analytes, along with outstanding storage stability, reproducibility, and repeatability. Owing to these attributes, the Ag-CeO₂/Ag₂O/GCE sensor proved effective for real sample analysis, showcasing its potential as a reliable, non-enzymatic platform for H₂O₂ detection. Full article

Due to its conjugated structure, 1,4,6,8-tetrakis((E)-2-(thiophen-2-yl)vinyl)azulene (L) has a high potential for nonlinear optics and coloring. This compound was studied electrochemically using cyclic voltammetry, pulse differential voltammetry and rotating disk voltammetry in organic electrolytes. The main processes occurring during oxidation and reduction scans were highlighted and characterized. Density functional theory (DFT) calculations were conducted to assess the chemical reactivity of this compound. UV-Vis studies of L were performed in acetonitrile to establish the optical parameters in this solvent and its complexing power towards heavy metal (HM) ions. Chemically modified electrodes (CMEs) based on L were prepared by electrooxidation of L in organic electrolytes. To evaluate the electrochemical behavior of the CMEs, they were characterized with a ferrocene redox probe. They were also tested for the analysis of synthetic samples of heavy metal ions (HM): Cd(II), Pb(II), Cu(II) and Hg(II) by anodic stripping. Specific responses were obtained for Pb(II) and Cd(II) ions. The preparation conditions have an influence on the electrochemical responses. This study is relevant for the design and further development of advanced materials based on this azulene for the analysis of HMs in water samples. Electrochemical experiments and DFT calculations recommended L as a new ligand for modifying the electrode surface for the analysis of HMs. Full article

Here, a highly sensitive and selective electrochemical sensor for dopamine (DA) determination in pork was developed. This sensor was fabricated using iron-based nanocomposites (Fe@(C-S-N)) to modify a glassy carbon electrode (GCE) substrate. The Fe@(C-S-N) nanocomposites were synthesized through a facile low-temperature chemical precipitation approach by adopting ferrous sulfate and melamine as raw materials, with their structural and compositional properties thoroughly investigated using multiple analytical techniques, including X-ray diffraction (XRD), electron microscopy (EM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectra (EDS). Cyclic voltammetry (CV), chronocoulometry (CC), and differential pulse voltammetry (DPV) were adopted to investigate the electrochemical performance of the fabricated Fe@(C-S-N)/GCE sensor. Notably, the sensor demonstrated a linear response range from 0.05 to 100 μM with a minimal limit of detection (LOD) of 46 nM. Lastly, the fabrication sensor was used to determine DA in pork samples, showing an acceptable recovery of over 96.89%. Thus, the proposed sensor could offer an effective method for determining DA in pork. Full article

In this study, we successfully prepared silver electrodes through a silver mirror reaction. By carefully regulating the amount of ammonia complexing agent in the silver–ammonia solution, we effectively suppressed the decomposition of the plating solution while reducing the surface roughness of silver films from 9.22 nm to 4.42 nm. The electrical conductivity of our solution-processed silver layers was nearly one order of magnitude higher than that of conventional inkjet-printed silver electrodes. When applied as source-drain electrodes in organic field-effect transistors (OFETs), these electrodes enabled devices with an average mobility of 0.13 cm²/(V·s) and remarkably low mobility variation of only 8.7%. Furthermore, we modified the silver electrodes through chemical platinum plating, achieving a significant 0.74 eV alteration in work function, which demonstrates the great potential of chemical plating for surface functionalization in solution-processed organic electronic devices. Full article

An advanced anodic stripping voltammetry (ASV)-based Micro Electro Mechanical System (MEMS) sensor for cadmium (Cd) detection is presented in this study, which is cost-effective and efficient for in situ water monitoring, providing a crucial early warning mechanism, streamlining environmental monitoring, and facilitating timely intervention to safeguard public health and environmental safety. The rationale behind this work is to address the critical need for an in situ monitoring system for cadmium (Cd) in freshwater sources, particularly those adjacent to agricultural fields. Cd(II) is a highly toxic heavy metal that poses a significant threat to agricultural ecosystems and human health due to its rapid bioaccumulation in plants and subsequent entry into the food chain. The developed analytic device is composed of a commercial mercury salt-modified graphite screen-printed electrode (SPE) with a custom-designed innovative polydimethylsiloxane (PDMS) flow detection cell. The flow cell was prototyped using 3D printing and replica moulding, with its design and performance validated through COMSOL Multiphysics simulations to optimize inflow conditions and ensure maximum analyte dispersion on the working electrode surface. Chemical detection was performed using square wave voltammetry, demonstrating a linear response for Cd(II) concentrations of 0 to 20 µg/L. The system exhibited robust analytical performance, enabling 25–30 daily analyses with consistent sensitivity within the Limit of Detection (LoD) set by the law of 3 µg/L. Full article

Metallo-phthalocyanines (MPcs) are versatile materials with applications in electroanalysis because of their superior catalytic properties. This review presents the electrochemical methods based on MPc-modified electrodes and reports some of their remarkable properties and applications in the electroanalysis of monoamine neurotransmitters and biomolecules that play a crucial role in vital functions of the human body. The development of electrocatalytic chemically modified electrodes is based on their ability to provide a selective and rapid response toward a specific analyte in complex media without the need for sample pretreatment. The explanation of several phenomena occurring at the MPc-modified electrode surface (e.g., MPc-mediated electrocatalysis), the advantages of promoting different electron transfer reactions, and the detection mechanism are also presented. The types of MPcs and different materials, such as carbon nanotubes and graphene, used as substrates for modified working electrodes are discussed. Modifying the properties of MPcs through various interactions, or combining MPcs with carbonaceous materials, creates a synergistic effect. Such hybrid materials present both extraordinary catalytic and increased conductivity properties. We conducted a compilation study based on recent works to demonstrate the efficacy of the developed sensors and methods in sensing monoamine neurotransmitters. We emphasize the analyte type, optimized experimental parameters, working range, limits of detection and quantification, and application to real samples. MPc–carbon hybrids have led to the development of sensors with superior sensitivity and improved selectivity, enabling the detection of analytes at lower concentrations. We highlight the main advantages and drawbacks of the discussed methods. This review summarizes recent progress in the development and application of metallo-phthalocyanine-modified electrodes in the electroanalysis of monoamine neurotransmitters. Some possible future trends are highlighted. Full article

The strong adsorption capacity of loess poses a significant limitation to the electrokinetic (EK) remediation process. Modified EK technologies, such as graphene oxide-alginate composite hydrogel (GOCH) electrodes, are increasingly employed for the remediation of heavy metal-contaminated loess. However, the complex interactions among multiple physical fields within these modified systems remain poorly understood. This study utilizes COMSOL Multiphysics version 6.0 to simulate diffusion, electromigration, electroosmotic flow, adsorption, and chemical reactions in loess contaminated with copper (Cu) and lead (Pb). A chemical precipitation and ion transport model, governed by the Nernst–Planck equation, was validated through a comparison of simulation results with experimental data. The investigation examines the effects of electrode placement and size on EK efficiency, revealing that diagonally placed irregular electrodes optimize the electric field, minimize ineffective regions, and enhance ion migration. Larger electrodes enhance current density, whereas smaller electrodes mitigate edge shielding effects. This research offers strategic insights into electrode configuration for improved EK remediation of Cu-Pb-contaminated loess, achieving greater efficiency than traditional systems. Full article