The simultaneous electrochemical determination of multiple biologically active molecules remains one of the greatest challenges in modern analytical chemistry because of their structural similarities, closely overlapping oxidation potentials, and strong mutual interferences. The present study focuses on a novel electrochemical sensing platform that enables the simultaneous, precise, and interference-free determination of 4-aminophenol (4-AP), dopamine (DA), and acetaminophen (AC) using a strategically engineered nanocomposite-modified electrode. The key innovation lies in the rational surface modification, typically involving noble metal nanoparticles (AuNPs), metal oxide (CuO-NiO) nanostructures, and carbon-based nanomaterials (SWCNTs), which enhance electron transfer kinetics and spatial separation of the oxidation peaks, thereby minimizing cross-reactivity. The desired nanocomposite was fabricated using a simple two-step synthesis route and characterized with several spectroscopic and microscopic techniques. The sensor electrode exhibits outstanding electrocatalytic performance due to its larger surface area, lower overpotential, and reduced Rct value, facilitating electron transfer during the sensing event. Differential pulse voltammetry (DPV) analysis yielded sensitivities of 1.374 µA/(µM·cm2) for 4-AP, 1.203 µA/(µM·cm2) for DA, and 0.129 µA/(µM·cm2) for AC. The limits of detection (LODs) were determined to be 0.106 µM, 0.122 µM, and 1.13 µM for 4-AP, DA, and AC, respectively. The proposed sensor demonstrates excellent selectivity for target biomolecules even in the presence of various interfering species. Additionally, the sensor exhibits outstanding stability under the current experimental conditions. Finally, recovery analysis was performed with two different ages of human blood serum (ages 27 and 67) to evaluate the sensor’s efficiency for real-life applications.

A simple and convenient approach was implemented in this study to synthesize Palladium nanoparticles (PdNPs) and single-walled carbon nanotubes (SWCNTs) decorated chitosan (CS)-based electrocatalyst for the first time to detect acetaminophen (AC) biomolecule. The SWCNTs enhance the catalytic capabilities of the as-fabricated nanocomposite by preventing CS from aggregating and establishing a direct link with PdNPs. Characterization of the newly developed nanocomposite was carried out with several microscopic and spectroscopic techniques. The neutral pH medium shows the highest electrochemical performances under optimized conditions. The electron transfer coefficient was obtained alpha = 0.721, overall electron transfer n = 2. Differential pulse voltammetry (DPV) was employed for the sensing study, where excellent linearity was obtained with a linear range of 2.31 to 42.04 & micro;M. DPV reveals a remarkable sensitivity of 2.43 & micro;A & micro;M-1cm-2, and LOD was 0.056 & micro;M. In addition, the i-t curve shows the experimental AC range 5 to 120 & micro;M, and the obtained sensitivity and LOD are 2.35 & micro;A & micro;M-1cm-2 and 0.058 & micro;M, respectively. Furthermore, the newly developed sensor electrode exhibited outstanding stability, excellent repeatability, and outstanding selectivity even in the presence of commonly used interfering substances. Pharmaceutical formulation (paracetamol tablet) and human urine were used as real samples to recover AC for the assurance of the sensor in the real world. These outcomes of the study emphasize that the synthesized nanocomposite has potential applications for the fabrication of a sophisticated electrochemical AC sensor for clinical and pharmacological monitoring.

Initially, six aliphatic electroactive luminescent terpolymers (ELTPs) are synthesized through polymerization of methacrylic acid, 3-(methacryloylaminopropyl)trimethylammonium chloride, and in situ attached 3-(N-(2-carboxypropyl)methacrylamido)-N,N,N-trimethylpropan-1-aminium chloride monomers. The optimized ELTP3-modified glassy carbon electrode (ELTP3-GCE) exhibits open-circuit potential (OCP) of 0.412 V. Thereafter, to enhance the opto-electronic performance, six dual-state emission electroactive luminescent nanohybrid terpolymers ELTP3-SNP1–6 are fabricated encapsulating different amounts of magnetic CoFe₂O₄-SiO₂/SO₃H nanoparticles in ELTP3 matrix. Spectroscopic and electrochemical investigations confirm ELTP3-SNP5 as the optimal nanohybrid displaying the highest subluminophore density/ OCP and confirming the involvement of metal centers/ polymer functionalities in the sensing and oxidation of NO₂⁻. The morphology, aggregation characteristics, metal-oxygen-/ hydrogen-bonding, dual-mode NO₂⁻ sensing and associated mechanisms, along with the electrocatalytic oxidation features of ELTP3-SNP5/ ELTP3-SNP5-GCE are elucidated using spectroscopic/ diffractometric/ dynamic light scattering/ microscopic characterizations and electrochemical measurements. Both solution phase and solid state emissions are demonstrated by excitation-dependent photoluminescence, red-shifted UV-absorption from ELTP3/ ELTP3-aggregate to ELTP3-SNP5/ ELTP3-SNP5-aggregate, solvent polarity effects, and lifetime measurements. The luminogenic NO₂⁻ sensing of ELTP3-SNP5/ ELTP3-SNP5-aggregate exhibits a detection limit of 13.38/ 18.78 nM. The voltammetric/ impedimetric sensing using ELTP3-SNP5-GCE achieves low detection limits down to 0.0773/ 0.2505 µM and high stability/ reproducibility in real water samples, highlighting its potential for sensitive environmental monitoring.

The photocatalytic conversion of carbon-dioxide (CO2) to methanol (CH3OH) under mild conditions has been regarded as a promising, cost-effective, and environmentally sustainable approach for carbon utilization and renewable fuel generation. However, the process has been hindered by limited charge separation efficiency and insufficient CO2 activation. In this study, a heterostructured Ag-Si/MgO/ZnO photocatalyst was rationally designed and synthesized via a solid-phase reaction method. A CH3OH production rate of 357.53 mu mol gcat-1 h-1 was achieved over the optimized 10% Ag-Si/MgO/ZnO composite catalyst at 250 degrees C, representing a substantial enhancement compared to the Si/ZnO and Si/MgO/ZnO photocatalysts. The CH3OH production performance was found to be higher in the photocatalyst/gas-phase system than that reported in comparable studies. The theoretical activation energy for Ag-Si/MgO/ZnO was found to be 158.14 kJ mol-1, which is lower than that of Si/MgO/ZnO (167.79 kJ mol-1) and Si/ZnO (177.97 kJ mol-1), indicating enhanced CO2 activation and higher CO2 conversion. More importantly, after more than 72 h of irradiation, the system still exhibited a high CH3OH production rate, demonstrating its potential for practical application.

This study explores the electrochemical reduction of H2O2 on an Au electrode containing potassium thiocyanate (KSCN) in an alkaline medium. The presence of thiocyanate (SCN-) ions in the reaction system modifies the Au electrode surface (SCN--modified Au) via self-assembled compact layer formation, confirmed by voltammetry, amperometry, and X-ray photoelectron spectroscopy (XPS). Acting as a 'gatekeeper', this adsorbed layer (abbreviated as 'adlayer') simultaneously overturns the oxidative degradation of H2O2 with dynamic adsorption-desorption behavior and significantly boosts the reduction reaction. Kinetic diagnosis reveals that the reaction is irreversible and diffusion-controlled, following first-order kinetics with a transfer coefficient (α) of 0.39 ± 0.02. Key analytical merits include a broad linear dynamic range spanning 50 to 2000 µM, a sensitive detection limit of 9.95 µM and operational stability with 97% signal retention. The practical utility of the SCN--modified Au electrode is validated through successful deployment in analyzing real industrial effluents, where it achieved high recovery rates, underscoring its potential for routine environmental and industrial analysis.

The pursuit of renewable clean energy resources has driven extensive research into the Hydrogen Evolution Reaction (HER) nowadays. Here, we have introduced a Ce-doped TiO2 electrocatalyst prepared via sol-gel method, demonstrating its capability as an excellent catalyst compared to the noble metal Pt for HER in an alkaline imidazole solution. Evaluating its electrochemical performance, we found that the GC-2at.%CeTiO2 catalyst surpassed the Pt electrode. The HER onset potential at GC-2at.%CeTiO2 is 0.20 V vs. RHE, which is a significant improvement over Pt (- 0.05 V). Impressively, it needed a considerably lower overpotential of 318 mV for reaching 5 mA cm- 2 current density, compared to Pt (631 mV). Electrokinetic parameters, for instance, Tafel slope, exchange current density (jk) and, turnover frequency (TOF) were calculated to be 121 mV dec-1, 1.148 mA cm- 2, and 0.015 s- 1, consecutively, that surpassed those of noble Pt electrode in this study (397 mV dec-1, 0.487 mA cm- 2, and 0.014 s-1 respectively). This improvement is credited to an increased electroactive surface area and a synergistic interaction linking the electronic state of the Ce and TiO2 matrix. DFT analysis revealed that the Ce3+ ion coordinated with the N-H group of imidazole, leading to elongation and weakening of the N-H bond. This structural modification facilitated the dissociation of the N-H bond, enabling the formation of hydrogen radicals and promoting efficient hydrogen evolution. Additionally, the catalyst demonstrated remarkable electrochemical stability under operating conditions. These findings provide valuable insight into the HER mechanism within an imidazole-mediated system and highlight the potential of Ce3+-imidazole interactions in advancing non-precious metal-based electrocatalysis.

The development of efficient and non-toxic fuels for direct liquid fuel cells has highlighted ascorbic acid (AA) as a sustainable energy source. This study presents a combined theoretical and experimental investigation of ascorbate oxidation on an Au-Pt electrode in alkaline medium. Density functional theory (DFT) calculations reveal that Au deposition on Pt creates a more homogeneous and active surface, significantly enhancing the adsorption energy of ascorbate (-7.54 eV vs. -5.80 eV on bare Pt). Electrochemically, this translates to a superior performance, where the Au-Pt electrode achieves a 38% reduction in charge-transfer resistance, a higher current density, and a lower Tafel slope of 77 mV dec-1, indicating accelerated kinetics. The electrode also retains its activity over 1000 cycles, confirming exceptional durability. This synergistic combination of theoretical and experimental results establishes Au-Pt as a premier catalyst for sustainable ascorbate-based energy conversion.

Sustainable energy conversion depends on the development of effective and economical electrocatalysts. In this work, we highlight the development of cobalt oxide (Co3O4) as an electrocatalyst by employing a scalable and economical Successive Ionic Layer Adsorption and Reaction (SILAR) method onto an electrically activated pencil graphite (Ac-PGE) as an affordable substrate for monitoring the oxygen evolution reaction (OER). According to electrochemical impedance spectroscopy, the SILAR process produced uniform deposition and improved surface activation, which resulted in a considerably reduced charge transfer resistance (R ct) of 0.08 kΩ. The OER overpotential was observed at 240 mV at 10 mA cm-2 with a Tafel slope of 47.57 mV dec-1, and a turnover frequency of 0.082 s-1 at the activated electrode. LSV and OCP demonstrate that Co3O4@Ac-PGE performs better electrochemically than the other electrodes under investigation (In-PGE, Ac-PGE, and Co3O4@In-PGE). Additionally, after 8 hours, it maintained more than 93% of its initial activity, demonstrating exceptional endurance. Overall, it was observed that the Co3O4@Ac-PGE electrode developed by the SILAR method outperforms a number of traditional and noble-metal-based catalysts and offers a practical, long-lasting, and financially sustainable approach to effective water-splitting and renewable energy conversion. The structural and surface properties of the modified electrodes were investigated using energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). This work shows a scalable and cost-effective strategy to design an efficient electrocatalyst by using SILAR for OER, which can contribute towards Green Hydrogen production.

To address the challenge regarding nitrate pollution from agriculture and industry, we developed a novel integrated system featuring a bimetallic membrane electrode assembly (Pt|Nafion|Pt–Cu) coupled with a suspended Pd–Cu/activated carbon (AC) catalyst for the nitrate reduction reaction (NRR) in low-conductivity media. This design leverages a synergistic mechanism, combining electrochemical reduction and catalytic hydrogenation for enhanced efficiency. The system demonstrated exceptional performance, achieving a high observed rate constant (kobs = 43.2 × 10−3 min−1) alongside superior product selectivity; notably low nitrite accumulation (15.8

Electrochemical nitrate reduction reaction (NRR) was investigated using Cu-modified Pt electrode prepared via controlled electrodeposition cycles. The aim was to systematically vary Cu content on Pt electrode (3 to 15 cycles) to evaluate its influence on catalytic activity, surface properties, and charge transfer kinetics during NRR in neutral medium. Voltametric analysis revealed a progressive increase in NRR performance, surface coverage, roughness factor, and double-layer capacitance reaching a saturation at 10 deposition cycles, beyond which no improvement was observed. However, kinetic analysis through Tafel plot and impedance parameters showed an opposite trend, where the exchange current decreased and charge transfer resistance increased with higher Cu content on Pt electrode. This indicates that although Cu content enhanced the electroactive surface area, it simultaneously suppressed the intrinsic electron transfer kinetics. Scan rate studies confirmed multi-step diffusion-controlled reaction pathway involving nitrate to nitrite, hydroxylamine, and ammonia. The study highlights the critical balance between surface area enhancement and modulation of intrinsic catalytic kinetics to achieve optimal performance of Pt-Cu electrode for NRR.

Oxygen reduction reaction (ORR), a key process in sustainable energy conversion, utilizing a perovskite catalyst to achieve higher currents at lower overpotentials along with the production of value-added product hydrogen peroxide (H2O2), serves the dual functionality of both energy production and a green route for H2O2 generation. Here, we report the synthesis of a highly efficient double perovskite La2NiMnO6 (LNMO), achieved through the incorporation of two transition metals, Ni and Mn, in the perovskite structure, and explore its activity for ORR. During ORR at a rotation rate of 1600 rpm in 1.0 M NaOH, LNMO exhibits an onset potential of 0.75 V (corresponding to a current density of 0.1 mA cm(-2)) and a Tafel slope of 95 mV dec(-1), achieving over 88% H2O2 selectivity and 73% faradaic efficiency across a wide potential range of 0.2-0.6 V vs RHE. Characterization techniques including OCP, EIS, ICP-OES, XRD, XPS, FE-SEM, and FTIR confirmed the successful preparation of LNMO and its catalytic activity. The kinetic investigation unveiled by the transfer coefficient (alpha) demonstrated that ORR on the LNMO surface followed a stepwise mechanism, involving an overall two irreversible electron transfer steps, where the first electron transfer was the rate-determining step. The analyses further revealed a diffusion-limited process for ORR accompanied by first-order kinetics with a standard rate constant (k(0)) of 3.97 x 10(-3) cm s(-1) and a formal potential (E-0) value of 0.96 V vs RHE. Finally, a stability test via chronoamperometry showed that LNMO outperformed the Pt/C catalyst.

The development of efficient and stable electrocatalysts for the hydrogen evolution reaction (HER) is crucial for advancing sustainable hydrogen production. In this study, a polyaniline (PANI)-supported Pd–Au bimetallic film on pencil graphite (PGP), denoted as Pd–Au–PANI@PGP, was fabricated and evaluated for HER activity in 0.5 M H₂SO₄. The catalyst was characterized using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDX), which confirmed the successful surface modification of PGP with Pd and Au, along with the polymeric network of PANI. The chemical composition and electronic structure were further examined by X-ray Photoelectron Spectroscopy (XPS), revealing a high proportion of metallic Pd and Au species. Electrochemical performance was assessed via linear sweep voltammetry (LSV), Tafel analysis, electrochemical active surface area (ECSA), and turnover frequency (TOF) measurements. The Pd–Au–PANI@PGP electrode exhibited an exceptionally low overpotential of 31.6 mV at 10 mA cm⁻², comparable to the benchmark Pt–C@GC catalyst (19 mV). The enhanced activity is attributed to the synergistic effect of Pd and Au, which facilitates electron transfer and accelerates catalytic kinetics. Tafel slope analysis confirmed that the HER process is primarily governed by the Volmer step, with Pd–Au–PANI@PGP exhibiting the lowest slope (91.44 mV dec⁻¹), indicative of improved reaction kinetics. The high exchange current density (4.65 mA cm⁻²) and large ECSA (1.64 cm²) further validate its superior catalytic activity. Moreover, the TOF of Pd–Au–PANI@PGP (0.0971 s⁻¹) significantly surpasses that of other modified electrodes, confirming its excellent intrinsic activity. Long-term stability, evaluated by chronoamperometry, showed negligible current degradation over 6 h, underscoring the durability of the catalyst. Overall, these results demonstrate that Pd–Au–PANI@PGP is a highly promising HER electrocatalyst, offering outstanding activity, rapid reaction kinetics, and excellent stability, making it a viable candidate for future hydrogen production applications.

Here, a series of electroactive polymer nanohybrids (EPNHs) is synthesized incorporating as-synthesized nitro graphene oxide (NGO) nanoparticles into the matrix of poly(N,N-dimethylacrylamide). Spectroscopic and electrochemical analyses of both EPNHs and EPNHs-modified Pt electrodes (PE|EPNHs) confirm EPNH3 as the optimal composition exhibiting the highest NGO grafting, open-circuit potential (OCP) of 1.1749 V, and conductivity (2.83 mS cm(-1)). To further increase the OCP and conductivity, EPNH3 is modified with untanned collagenic waste (UCW) to prepare a new series of electroactive nano-bio-polymer hybrids (ENBPHs). Comprehensive spectroscopic, diffractometric, microscopic, and electrochemical analyses of ENBPHs/PE|ENBPHs confirm ENBPH3 as the optimal composition carrying the maximum amount of UCW, the highest OCP (1.1818 V), and significantly improved conductivity (65.12 mS cm(-1)). Then, cyclic voltammetric and impedimetric sensing experiments are carried out to evaluate the I- sensing performance of PE|ENBPH3 electrode in distilled, tap, and pond water. Spectroscopic and electrochemical measurements confirm electrooxidation of I- to I-3(-) and subsequently to I-2 through proton transfer from -N+O2H/ -COOH/ -OH group to I- and electron transfer from I- to >CN+. Impedance spectroscopic analysis confirms notable decrease in porous layer resistance because of the anion-pi* interaction between I- and NGO. The limits of detection are measured to be 5.89, 6.60, and 7.81 mu M (cyclic voltammetric titration) and 4.64, 4.72, and 4.85 mu M (impedimetric titration) in distilled, tap, pond water, respectively. The sensitivity, selectivity, reproducibility, and interference studies confirm the suitability of ENBPH3 toward cyclic voltammetric and impedimetric sensing/ detection of I- in real aqueous solutions.

The oxygen reduction reaction (ORR) is a pivotal electrochemical process in energy technologies and in the generation of hydrogen peroxide (H2O2), which serves as both an effective agent for dye degradation and a fuel in H2O2-based fuel cells. In this regard, a titanium (Ti) sheet was anodized to generate a TiO2 layer, and then the oxide layer was modified with gold (presented as Au/TiO2/Ti) via electrodeposition. The developed electrocatalyst was confirmed by X-ray photoelectron spectroscopy (XPS), which showed characteristic binding energies for Ti4+ in TiO2 and metallic Au. In addition, the Nyquist plot verified the electrode modification process, since the diameter of the semicircular arc, corresponding to charge transfer resistance, significantly decreased due to Au deposition. Voltametric studies revealed that the TiO2 layer with a Ti surface exhibited a good synergistic effect on Au and the ORR in a bicarbonate medium (0.1 M KHCO3) by lowering the overpotential, enhancing current density, and boosting durability. The scan rate-dependent study of the ORR produced by the developed electrocatalyst showed a Tafel slope of 180 ± 2 mV dec−1 over a scan rate range of 0.05–0.4 V s−1, thereby indicating a 2e− transfer process in which the initial electron transfer process was the rate-limiting step. The study also revealed that the Au/TiO2/Ti electrode caused oxygen electro-reduction with a heterogenous rate constant (k0) of 4.40×10−3 cm s−1 at a formal potential (E0′) of 0.54 V vs. RHE.

The rapid advancement of modern electronic technologies has significantly enhanced social production efficiency, but it has also led to an increase in electromagnetic interference (EMI). As a result, electromagnetic shielding materials have gained considerable attention, particularly in the context of lightweight and highly integrated electronic devices. Polymers are widely utilized in EMI shielding applications due to their unique properties, such as light weight, high flexibility, and excellent corrosion resistance. This review focuses on well-studied polymer-based lightweight composites. The fundamental theory of EMI shielding is thoroughly introduced, and current testing methods for evaluating shielding effectiveness are summarized to assist in the development of design principles for effective shielding materials. Additionally, the impact of various carbon materials—classified into zero-dimensional, one-dimensional, two-dimensional, and three-dimensional forms—on shielding performance is discussed, along with their corresponding shielding mechanisms. These advanced lightweight materials with superior EMI shielding properties hold immense potential for applications across diverse sectors, including communications, electronics, aerospace, military, and environmental protection.

A low-cost glassy carbon electrode (GCE), modified with minimum amount of noble metal rhodium (Rh) via electrodeposition method can sensibly enhance the electrocatalytic oxygen reduction reaction (ORR) in H3PO4 solution (pH similar to 2.0). The successful Rh electrodeposition was confirmed by using field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron microscopy (XPS). The rotating disk electrode (RDE) technique was used in kinetic investigation to confirm the ORR mechanism followed by the 4e- transfer process, resulting in the production of water as the final product on the Rh-GCE surface. This finding was further supported by rotating ring disk electrode (RRDE) analysis. The transfer coefficient (alpha) value was determined similar to 0.36, indicated the protonation and electron transfer process in the rate-limiting step of the ORR followed a concerted pathway. The exchange current density (j0) and standard rate constant (ko) were determined to be 1.09 x 10-4 A cm-2 and 2.35 x 10-4 cm s-1, respectively.

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.

ObjectivesCoronavirus 2019 (COVID-19) has spread throughout the world and the current COVID-19 vaccines have shown to be the most effective means of combating the COVID-19. This study focused to examine the status of serum biomarkers in individuals infected and non-infected with SARS-CoV-2, both before and after COVID-19 pandemic and vaccination.MethodsThis study comprised 133 adults aged 35 and older including both academic and non-academic personnel associated with Shahjalal University of Science and Technology in Sylhet, Bangladesh. Participants were evaluated before and after COVID-19 pandemic, as well as following two doses of vaccination. Blood samples were collected to measure different serum biomarkers, including fasting blood sugar (FBS), serum creatinine, serum alanine transaminase (ALT), total cholesterol (TC), triglyceride (TG), Low density lipoprotein-cholesterol (LDL-C), and High density lipoprotein-cholesterol (HDL-C). Statistical analysis was performed using SPSS software.ResultIn all participants, serum creatinine, FBS and TC levels significantly increased after two doses of vaccination (p = 0.022, 0.006, 0.05) compared to pre-vaccination levels. Notably, all serum biomarkers showed a significant elevation (p ≤ 0.05) in the self-reported SARS-CoV-2 infected group (n = 44). Additionally, 31% of participants were newly diagnosed with hyperglycemia after receiving the COVID-19 vaccine.ConclusionThe findings indicate that both self-reported SARS-CoV-2 infection and COVID-19 vaccination could influence different serum biomarker levels. However, further comprehensive research is necessary to discern the precise factors contributing to the alterations observed in the serum biomarker levels for future health management strategy.

In this study, we present a comprehensive theoretical and experimental investigation of the electrocatalytic oxidation of arsenite on Au immobilized Pt surfaces in a neutral medium. Theoratically, density functional theory (DFT) calculations revealed that thePt-Au bimetallic system exhibits superior adsorption energy (Eads = -2.045 eV) compared to bare Au (-0.611 eV) and Pt (-0.769 eV) surfaces, indicating enhanced arsenite affinity and catalytic activity. Experimental characterizations, including SEM, PXRD, EIS, and CV, confirmed the formation of noble catalytic sites on Au and synergistic effects between Au and Pt, facilitating efficient As(III) oxidation. The reaction followed first-order kinetics with a diffusion-controlled mechanism, as evidenced by a diffusion coefficient of 3.20 × 10-7 cm2s-1. Tafel analysis further elucidated the reaction kinetics, revealing a reduced Tafel slope (277 mVdec-1) for the Pt-Au electrode, indicative of improved charge transfer. Activation polarization analysis demonstrated lower overpotential (|ηa| = 1.28 V) for thePt-Au system compared to bare Pt (1.56 V), highlighting its enhanced catalytic efficiency and internal synergy after Au deposition. The findings align with theoretical predictions, underscoring the potential of Pt-Au bimetallic surfaces for arsenic sensing.

Groundwater is the principal source of drinking water for the residents of the Bengal Delta Plain. However, its quality has reportedly been declining due to various anthropogenic and geogenic activities. Therefore, it is crucial to investigate the current status of groundwater quality for sustainable resource management. This study aims to assess the current groundwater chemistry and evaluate the drinking water quality in the northwestern region of Bangladesh within the Bengal Delta, using multivariate statistical methods and water quality index (WQI) calculation. Data on various water quality parameters—fluoride, calcium, chloride, potassium, sodium, ammonium, nitrate, magnesium, pH, electrical conductivity (EC), water hardness, TOC, sulfate, carbonate, bicarbonate, trace and heavy metal profiles—were obtained from 128 sites across five sub-districts (also known as Upazila) in north-western Bangladesh. The results indicate that majority of the parameters met the standards defined by the WHO, except for NO3− in Baliadangi Upazila, where the study identified the underlying cause of this NO3− contamination. The WQI classified the 120 samples as follows: 55.00