Electroanalytical Parameters Research Articles

Comparative electrochemical study of veterinary drug danofloxacin at glassy carbon electrode and electrified liquid–liquid interface

This work compares the electroanalytical performance of two electroanalytical systems based on (1) the glassy carbon electrode (GCE), and (2) the electrified liquid–liquid interface (eLLI), for the detection of fluoroquinolone antibiotic–danofloxacin (DANO). Our aim was to define the optimal conditions to detect the chosen analyte with two employed systems, extract a number of electroanalytical parameters, study the mechanism of the charge transfer reactions (oxidation at GCE and ion transfer across the eLLI), and to provide physicochemical constants for DANO. Detection of the chosen analyte was also performed in the spiked milk samples. To the best of our knowledge, this is the first work that directly compares the electroanalytical parameters obtained with solid electrode (in this case GCE) and eLLI. We have found that for DANO the latter provides better electroanalytical parameters (lower LOD and LOQ) as well as good selectivity when the milk was analyzed.

The Impact of Ar or N2 Atmosphere on the Structure of Bi-Fe-Carbon Xerogel Based Composites as Electrode Material for Detection of Pb2+ and H2O2.

In this study, bismuth- and iron-embedded carbon xerogels (XG) were obtained using a modified resorcinol formaldehyde sol-gel synthesis method followed by additional enrichment with iron content. Pyrolysis treatment was performed at elevated temperatures under Ar or N2 atmosphere to obtain nanocomposites with different reduction yields (XGAr or XGN). The interest was focused on investigating the extent to which changes in the pyrolysis atmosphere of these nanocomposites impact the structure, morphology, and electrical properties of the material and consequently affect the electroanalytical performance. The structural and morphological particularities derived from X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements revealed the formation of the nanocomposite phases, mostly metal/oxide components. The achieved performances for the two modified electrodes based on XG treated under Ar or N2 atmosphere clearly differ, as evidenced by the electroanalytical parameters determined from the detection of heavy metal cations (Pb2+) or the use of the square wave voltammetry (SWV) technique, biomarkers (H2O2), or amperometry. By correlating the differences obtained from electroanalytical measurements with those derived from morphological, structural, and surface data, a few utmost important aspects were identified. Pyrolysis under Ar atmosphere favors a significant increase in the α-Fe2O3 amount and H2O2 detection performance (sensitivity of 0.9 A/M and limit of detection of 0.17 μM) in comparison with pyrolysis under N2 (sensitivity of 0.5 A/M and limit of detection of 0.36 μM), while pyrolysis under N2 atmosphere leads to an increase in the metallic Bi amount and Pb2+ detection performance (sensitivity of 8.44 × 103 A/M and limit of detection of 33.05 pM) in comparison with pyrolysis under Ar (sensitivity of 6.47·103 A/M and limit of detection of 46.37 pM).

Conductive polymer-based modified electrode for total antioxidant capacity determination

A poly(3,4-ethylenedioxythiophene)-modified glassy carbon electrode (PEDOTvx/GCE) was prepared by electropolymerization at different scan rates (v) from a monomer EDOT solution by co-doping with an organic dopant (sodium dodecyl sulphate, SDS) and an inorganic compound (LiClO4). The PEDOTv10/GCE modified electrode, which exhibited the highest surface area, was investigated by cyclic voltammetry (CV) at different scan rates or pHs of electrolyte solution, and by differential pulse voltammetry (DPV). The electrochemical and electroanalytical parameters were expressed using caffeic acid, a reference substance. The new modified electrode was used to estimate the antioxidant activity (AA) in different varieties of wines (white, rose, and red). For all types of wines, a good correlation between AA results obtained by electrochemical and spectrophotometrically FRAP assay was obtained.

Bioengineered Flagellin–TiO2 Nanoparticle-Based Modified Glassy Carbon Electrodes as a Highly Selective Platform for the Determination of Diclofenac Sodium

This study describes the incorporation of bioengineered flagellin (4HIS) protein in conjunction with TiO2 anatase nanoparticles into a chitosan (Chit) polymeric matrix as a highly sensitive electrode modifier for the determination of diclofenac sodium (DS) in wastewater. Two types of electrodes were prepared using a simple drop-casting method. The inner structure of the obtained modified electrode was characterized by scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy and isothermal titration calorimetry (ITC). The electrochemical and electroanalytical parameters of DS oxidation at the nanostructured interface of the modified electrode were obtained via cyclic voltammetry and square-wave voltammetry. The analytical parameters for diclofenac electro-detection showed a 50% decrease in LOD and LOQ at Chit + TiO2 + 4HIS/GCE-modified electrode compared with the Chit + 4HIS/GCE-modified electrode. The obtained tools were successfully used for DS detection in drug tablets and wastewater samples. Thus, it was demonstrated that in the presence of a histidine-containing flagellin variant, the electrode has DS recognition capacity which increases in the presence of TiO2 nanoparticles, and both induce excellent performances of the prepared tools, either in synthetic solution or in real samples.

Voltammetric MDMA Analysis of Seized Ecstasy Samples

(1) Background: 3,4-Methylenedioxymethamphetamine (MDMA) is an illicit drug that is sold as ecstasy. We aimed to develop a voltammetric method based on a chemically modified electrode (CME) to analyze MDMA. (2) Methods: The CME was evaluated with respect to the percentage of modifier, pre-concentration time, electroanalytical parameters, and selectivity. Then, the performance of the new voltammetric method was compared to the performance of color tests and chromatographic analyses (GC-MS and UPLC-MS) during the analysis of 11 seized ecstasy batches. (3) Results: The modifier percentage (v/v) of 1.5% provided the best CME. The electroanalytical parameters were in a linear range from 4.06 to 25.42 µmol L−1, SD = 0.018 µA, m = 84.0 × 103 µA L mol−1, r = 0.999, LD = 0.64 µmol L−1, and LQ = 2.17 µmol L−1. The CME was selective for MDMA. The MDMA concentration in the analyzed ecstasy lots ranged from 0 (without MDMA) to 63% (w/w). The voltammetric method developed for quantifying MDMA in ecstasy lots proved feasible and accurate (with a relative percentage error of ≤ ±13.2%). (4) Conclusions: The CME developed herein showed greater sensitivity (m) and lower LD and LQ for quantifying MDMA traces, paving the way for the use of voltammetric methods during forensic investigations.

Synthesis and Applications of Crown Ether-Linked Metal–Organic Framework Composite-Based Sensors for Stripping Voltammetric Determination of Lead

The present work demonstrates the construction and electrochemical characterization of novel disposable screen-printed carbon sensors integrated with functionalized MIL-53-NH2 metal–organic framework cross-linked with crown ethers and calixarene macrocyclic compounds for sensitive differential pulse voltammetric determination of lead ions in tap, surface water and biological fluid samples. The electroanalytical parameters were optimized regarding the nature of the electrode modifier, supporting electrolyte, the working pH value, scan rate, deposition potential, deposition time, reproducibility of measurement and the operational lifetime. Working electrodes dropcasted with MIL-53-NH2-dibenzo-24-crown-8-ether nanocomposite (MOFCE24) showed the proper performance within the lead concentration ranging from 13.75 to 217.83 ppb with LOD and LOQ values of 3.18 and 9.62 ppb, respectively. The synergistic effect of the metal–organic frameworks as transducer and dibenzo 24-crown-8-ether as sensing elements accelerates the electron transfer process at the electrode surface and improves the sensor selectivity through complexation of the lead ions with the crown ether moiety. The fabricated sensors showed high measuring reproducibility with long operational life time (60 days), which can be attributed to the formation of cross-linked ionophore/metal–organic framework with limited leaching of the sensing element in the measuring solution. The introduced sensors were utilized for the onsite voltammetric determination of lead in environmental and biological samples with acceptable average recoveries comparable with the graphite furnace atomic absorption spectrometric method.

Bilirubin determination at the electrified liquid-liquid interface supported with a 3D printed capillary

In this work, we have studied the behavior of bilirubin at the electrified liquid-liquid interface using two voltammetric techniques - cyclic and differential pulse voltammetry. The effect of bilirubin concentration as the analyte, and the influence of the aqueous phase pH on the interfacial behavior were investigated. Our focus was to optimize the electroanalytical determination protocol of bilirubin at the electrified liquid-liquid interface with the buffered aqueous phase (physicochemical study) and/or artificial urine formulation (analytical study). In this respect, we have extracted a number of electroanalytical parameters concerning bilirubin covering limits of detection and quantification and sensitivities. To push the optimized protocol towards applicability, we have designed and fabricated a 3D printed polyamide based tube finished with an aperture supporting a soft junction. Liquid-liquid interface placed in a fabricated support was characterized using voltammetry and scanning electron microscopy. With 3D printed platform we have significantly reduced the amount of consumed chemicals (from a few mL to a few tens of µL) and obtained a few times lower limit of determination as compared with the macroscopic apparatus.

Designing hybrid nanocubes-like cobalt stannate with appliance of MWCNT's nano composite for electrochemical detection of dopamine in bio-clinical samples

In this work, Co2SnO4 having nanocubes like structure synthesized via simple co-precipitation method and the nano-composite was prepared with appliance of multi-walled carbon nanotubes (MWCNT's) and employed for the determination of neuro-transmittance of dopamine (DA) in biological sample. The Co2SnO4 nanocubes and Co2SnO4@MWCNTs are characterized through distinct spectroscopic and microscopic methods, such as Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction spectroscopy (XRD), Raman spectroscopy, Filed emission scanning electron microscopy (FE-SEM), and electron spectroscopy for chemical analysis (ESCA) and as well as electrocatalytic activity was examined by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry techniques. Under optimal circumstances, the nano composite exhibited better activity over bare GCE. Moreover, Glassy carbon electrode (GCE) modified with Co2SnO4@MWCNTs was high sensitive and selective towards the determination of DA in presence of common interfering biomolecules. The electro analytical parameters via wide linear range (50–350 nM), low detection limit of 10.3 nM, sensitivity 0.043 nM mAcm−2 obtained by DPV analysis. The reliability of the Co2SnO4@MWCNTs/GCE electrode confirmed by real sample analysis of human urine sample and dopamine hydrochloride injection shows favor recovery percentage.

Superficial and Inkjet Scalable Printed Sensors Integrated with Iron Oxide and Reduced Graphene Oxide for Sensitive Voltammetric Determination of Lurasidone.

The present work demonstrated the fabrication and the electrochemical characterization of novel printed electrochemical sensors integrated with an innovative nanosensing platform based on the synergic electrocatalytic effect of iron oxide nanoparticles (FeONPs) and reduced graphene oxide (rGO) for precise voltammetric determination of the antipsychotic drug lurasidone hydrochloride (LUH). The features of the electrode surface fabricated using the ordinary inkjet printer were characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Among different ink formulations, integration of the printing ink with the ratio 15 mg FeONPs and 20 mg rGO was found to be the most appropriate for sensitive quantification of LUH in biological fluids and pharmaceutical formulations in the presence of LUH degradation products. Under the optimized experimental and electroanalytical parameters, the recorded square-wave voltammograms were correlated to LUH within the linear concentration ranging from 50 to 2150 ng mL-1 with detection limit and limit of quantification values of 15.64 and 47.39 ng mL-1, respectively. Based on the cyclic voltammograms recorded for LUH at different scan rates, the electrode reaction was assumed to be a diffusion reaction mechanism accompanied by the transfer of two electrons/protons through the oxidation of the five-membered ring nitrogen atom as assumed by the molecular orbital calculations carried out on the LUH molecule. The C max of LUH and the efficiency of the fabricated sensors enabled their clinical application for monitoring LUH in human biological fluids and pharmaceutical formulations in the presence of degradants for diverse quality control applications and green chemistry analysis.

Carbonaceous nanomaterials integrated carbon paste sensors for adsorptive anodic voltammetric determination of butenafine in the presence of its degradation product

Butenafine (BUT) is a new synthetic benzylamine antifungal with an effective inhibitory effect on squalene epoxidase. The present work introduced for the first time a novel sensitive adsorptive differential pulse voltammetric method for sensitive and selective determination of butenafine in pharmaceutical preparations in the presence of its degradation products. Integration of the working carbon paste electrodes with various carbonaceous nanostructures with their enhanced electrocatalytic effect towards the oxidation of butenafine improved the performance of the method. Comprehensive and in-depth studies were performed including the effect of the nature of the nanomaterial, modification mode, and pH under the optimized electroanalytical parameters. Functionalized carbon paste electrodes with multiwall carbon nanotubes (MWCNTs) showed a sharp well-defined oxidation peak for butenafine at 1.119 V following an adsorption electrode reaction mechanism through the participation of one proton/electron, as assumed by the pH, scan rate studies and molecular orbital calculations. Improved sensitivity was recorded within the linear BUT concentration range from 2.0 to 18.0 µg mL−1 with limit of detection 0.477 µg mL−1. A prolonged operational lifetime of more than 4 months and high measurement reproducibility was the promising futures of the fabricated sensors. The selectivity of the proposed method was established in the presence of the BUT degradation product and other interfering species present in pharmaceutical formulations. The achieved selectivity and sensitivity suggested the application of the proposed approach for BUT assay in medicinal creams in the presence of butenafine degradation products.

Voltammetric Electrochemical Behavior of Carbon Paste Electrode Containing Intrinsic Silver for Determination of Cysteine

In this paper, the electrochemical behavior of cysteine is described, using carbon paste electrodes (CPEs) modified with ternary silver-copper sulfide containing intrinsic silver at two pH values (pH 3 and 5). Experiments have revealed that presence of cysteine has a large impact on the electrochemical behavior of modified CPEs. Observed phenomena take place in solution, as well as at the surface of the modified CPEs, and can be applied for electroanalytical purposes. Based on the electrochemical behavior observed in the examined system, differential pulse voltammetry (DPV) was selected as an electroanalytical method for determination of cysteine. The effects of the various parameters on the electroanalytical signal, such as the amount of electroactive material, electroanalytical parameters, pH etc., were investigated using differential pulse voltammograms. The results indicated that electrochemical signal characterized with well-defined cathodic peak at 0.055 V vs. Ag/AgCl (3 M) in acetic buffer solution at pH 5 can be used for indirect electrochemical determination of cysteine. The optimization procedure revealed that the most sensitive and stabile electrode was that containing 5% modifier. The DPV response of the electrode, in the presence of cysteine, showed two different linear concentration ranges of 0.1 to 2.5 μM, and 5.6 to 28 μM. The explanation of the origin of two linear ranges is proposed. The lower concentration range was characterized by remarkable sensitivity of the 11.78 μA μM−1, owing to the chosen indirect method of determination. The calculated limit of detection (LOD), as well as limit of quantification (LOQ) were 0.032 and 0.081 μM, respectively. The influence of interfering agents on the electroanalytical response was examined, and low or no interference on the DPVs was observed. The proposed method was validated and applied for the determination of cysteine in pharmaceutical preparations with satisfactory recoveries in the range of 97 to 101.7%.

Electrochemical behavior of cocaine cutting agents at the polarized liquid-liquid interface

In this work, we have used cyclic voltammetry to investigate the interfacial behavior of cocaine cutting agents at the electrified liquid-liquid interface formed between a solution of the water and 1,2-dichloroethane phases. Among 27 chemical species used to adulterate cocaine street samples, only 8 were detectable in the available potential window. These include procaine, lidocaine, levamisole, hydroxyzine, caffeine, phenylethylamine, diltiazem, and diphenhydramine. From the calibration curves obtained using voltammetric data, we have extracted the electroanalytical parameters such as detection sensitivities, limits of detection, and limits of quantifications. Also, for each electrochemically active drug, we have calculated diffusion coefficients and plotted the ion partition and concentration fraction diagrams. All this information is discussed in a view of the cocaine sensors development focused on its detection from demanding matrix defined by the street samples composition.

Use of carbon black based electrode as sensor for solid-state electrochemical studies and voltammetric determination of solid residues of lead

For the first time carbon black based electrode modified with paraffin was applied as a sensor on voltammetry of immobilized microparticles (VIMP) approach for determination of lead solid residues in hair dye samples. The solid microparticles of Pb(II) (Pb(CH3COO)2(s)) immobilized into the carbon paste sensor containing carbon black and paraffin were firstly reduced at initial potentials and further reoxidized at around −0.60 V during anodic scan. Electroanalytical parameters as well as supporting electrolyte composition, and pH were also evaluated. An analytical curve in 0.2 mol L−1 phosphate buffer solution (pH 5.0) from 0.04 to 3.2 μg (R2 = 0.999) with detection and quantification limits of 4 and 13 ng, respectively, were achieved. The method was applied to quantify lead solid residues in hair dye samples without previous mineralization or complex sample pre-treatment. Besides adequate repeatability, stability and selectivity of the developed sensor based on VIMP features, the method using carbon black based sensor was considered advantageous comparing to the results recorded by a spectrometric method (relative error lower than 8%) from several analytical viewpoints.

Manganese dioxide (MnO2)/Fullerene-C60-Modified Electrodes for the Voltammetric Determination of Rifaximin

Rifaximin (RFX) is a broad-spectrum oral antibiotic with bactericidal actions against Gram-negative and Gram-positive bacteria. In the present work, a sensitive voltammetric assay for the RFX in pharmaceutical formulations is designed using nanostructured working electrodes. Surface functionalization with manganese dioxide (MnO2)/fullerene-C60 nanocomposite exhibited the highest electrochemical responses with a sharp oxidation peak at about 336 mV that was obtained using the differential pulse voltammetry (DPV). The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were applied, while the electrode matrix composition including types of nanomaterials, electroanalytical parameters, and pH effect were optimized. To that end, using the DPV, high sensitivity was obtained from the linear calibration curve ranged from 0.8 to 31.5 µg·mL−1 with the correlation coefficient of 0.99, limit of detection of 0.76 µg·mL−1 and limit of quantification of 2.31 µg·mL−1. Accordingly, the designed approach is offering a potential applicability towards the RFX determination in pharmaceutical preparations and its quality control.

Determining nadifloxacin in pharmaceutical formulations using novel differential pulse voltammetric approach

The present study suggested a novel analysis protocol for sensitive differential pulse voltammetric determination of nadifloxacin (NF). The performance of the working carbon paste electrodes (CPE) were improved via incorporation of different carbonaceous nanomaterials such graphene nano sheets (rG), fullerene-C60, multiwall carbon nanotubes (MWCNTs) and single wall carbon nanotubes (SWCNTs). Through assay optimization, comprehensive and deep parallel studies were conducted concerning the electrode matrix composition, mode of electrode modification, electroanalytical parameters and pH effects. Anodic oxidation peak were recorded at 1.02 V at pH 4 with an irreversible diffusion-controlled process. To that end, using the differential pulse voltammetry, high sensitivity was achieved in the NF concentration ranged from 3.3 to 53.3 μmol and limit of detection reached 0.250 μmol with improved stability and reproducibility. Moreover, the electrode reaction mechanism was studied electrometrically and sustained with the molecular orbital calculations. The interferences issues were also taken into consideration. Accordingly, the designed approach offers potential applicability towards nadifloxacin determination in pharmaceutical preparations with acceptable recoveries compared with the reported methods.

Electrochemical Detection and Degradation of Carbendazim at Poly (Vat Violet 2r) Modified GCE

To increase the electrochemical activity of the working electrode, vat violet 2R dye was electro-polymerized on the GCE surface i.e., poly (VVR)/GCE. Utilizing various voltammetric techniques including such cyclic voltammetric (CV), differential pulse voltammetric (DPV), and square wave voltammetric (SWV) technique, the fabricated glassy carbon electrode demonstrated excellent electrocatalytic behaviour against the electro-oxidation of carbendazim (CBM) in a 0.2 M PBS 3.0 pH. There has been observed a well resolution peak of the CBM with enhancement in the current for the developed GCE. The impact of electroanalytical parameters such as accumulation time, temperature variation, pH, heterogeneous rate, transfer coefficient, sweep rate, activation energy, as well as total count of electrons and protons have been evaluated in the CBM electro-oxidation mechanism. The real samples like water and soil samples were investigated using voltammetric techniques. The developed sensor is sensitive for the investigation of fungicide CBM by the determination of detection and quantification limit of CBM.

ELECTROCHEMICAL DETECTION OF TETRACYCLINE AS EMERGENT POLLUTANT IN WATER USING CARBON NANOFIBER-CoAl2O4 ELECTRODE

The aim of this study was to develop an electrochemical procedure for the advanced detection of tetracycline (TC) in water using CoAl2O4 dispersed onto carbon nanofiber-epoxy composite electrode substrate, which was selected from a series of tested carbon-based electrode substrates, i.e., commercial glassy-carbon and boron-doped diamond electrodes and home-made carbon nanotubeepoxy and carbon nanofiber-epoxy composites. Carbon nanofiber-epoxy composite electrode was found the best host for CoAl2O4 modifier based on the electrocatalytic effect towards TC oxidation and detection using cyclic voltammetry (CV) technique. The electrochemical techniques applied for electrochemical detection applications were CV, differential-pulse voltammetry (DPV), square-wave voltammetry (SWV) and chronoamperometry (CA). All the tested electrochemical techniques allowed TC determination and the electroanalytical parameters varied related to the technique type. DPV operated at the step potential of 50 mV and the modulation amplitude of 200 mV allowed the lowest limit of detection of 9 nM for TC determination. The recovery test applied for real surface water spiked with known TC concentrations among the reproducibility and the repeatability showed the great potential for the advanced quantitative determination of TC in real water or in pharmaceutical formulations.

Screen-printed electrochemical-based sensor for taxifolin determination in edible peanut oils

An electrochemical method for the determination of Taxifolin (Tx) in peanut oil samples using screen-printed electrodes (SPEs) is reported for the first time. The different electroanalytical parameters such as scan rate, supporting electrolyte, pH and accumulation step were optimized. Interference studies were also explored for the determination of Tx in presence of daidzein, quercetin, trans-resveratrol and caffeic acid. The method developed for the Tx determination exhibits a linear response in the concentration range from 0.05 to 1 μM and a limit of detection of 0.021 μM. The electrochemical detection method proposed provides a novel, quick, low-cost, reliable and portable method for the in-situ quality control for monitoring the protected designation of origin of the “Córdoba, Argentina, Peanuts”.

Cytochrome P450 3A4 as a Drug Metabolizing Enzyme: the Role of Sensor System Modifications in Electocatalysis and Electroanalysis

The electroanalytical characteristics of the recombinant cytochrome P450 3A4 (CYP3A4) immobilized on the surface of screen-printed graphite electrodes modified by multi-walled carbon nanotubes (MWCNTs) have been investigated. The role and the influence of the modification of a graphite working electrode by carbon nanotubes on the electroanalytical parameters of this cytochrome have been demonstrated. The conditions for its immobilization on the obtained screen-printed graphite electrodes modified by MWCNTs have been optimized. The electrochemical parameters of the oxidation and reduction of the enzyme heme iron ion were determined: these included midpoint-potential (E0') of –0.35 ± 0.01 V (relative to the silver/silver chloride reference electrode, Ag/AgCl); the electrochemical rate constant of heterogeneous electron transfer (ks) of 0.57 ± 0.04 s–1, the amount of electroactive CYP3A4 on the modified electrode (Γ0) of (2.6 ± 0.6) × 10–10 mol/cm2. The functioning mechanism of this electrochemical sensor followed the principle of “protein film voltammetry” (i.e. voltammetry of a protein film on the electrode surface). In order to develop medical biosensors using immobilized CYP3A4 for electroanalysis of drug substances, the substrates of this hemoprotein, we performed a voltammetric study of the catalytic activity of immobilized CYP3A4. We investigated electrocatalytic properties of the recombinant CYP3A4 immobilized on modified screen-printed graphite electrode using macrolide antibiotic erythromycin as a substrate. The modification of electrodes has been shown to play a decisive role for the study of the properties of cytochromes P450 in electrochemical studies. Smart electrodes can serve as electroanalyzers for analytical purposes, as well as electrocatalysts for the study of biotransformation and metabolic processes. Electrodes modified with carbon nanomaterials are applicable for analytical purposes in the registration of hemoproteins. Electrodes modified with synthetic membrane-like compounds (for example, didodecyldimethylammonium bromide) are effective in enzyme-dependent electrocatalysis.

Bi2O3 Nanoparticles Decorated Carbon Nanotube: An Effective Nanoelectrode for Enhanced Electrocatalytic 4-Nitrophenol Reduction.

4-Nitrophenol (4-NP) is present in most industrial waste water resources as an organic pollutant, and is a highly toxic and environmentally hazardous pollutant. Herein, we report that bismuth oxide (Bi2O3) decorated multi-walled carbon nanotubes (Bi2O3@MWCNTs) are the most prominent electrocatalyst for 4-NP electroreduction in acidic conditions. The electrocatalyst is synthesized by a simple chemical reduction method using ethylene glycol as a capping agent. The synthesized Bi2O3@MWCNTs electrocatalyst has been well-characterized by Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. Bi2O3@MWCNTs have a cubic structure which is confirmed by XRD. TEM imaging reveals Bi2O3 NPs are ~2 nm in size, are grown on MWCNTs and that these nanoparticles are active toward 4-NP electroreduction. The electrochemical studies by cyclic voltammetry measurements show that the Bi2O3@MWCNTs electrocatalyst can sense 4-NP at a very low potential i.e., −0.17 vs. saturated calomel electrode (SCE). Furthermore, electroanalytical parameters like scan rate and concentration dependence were studied with electrochemcial impedance spectroscopy (EIS) and the effect of pH on cathodic current was examined under experimental conditions. The lower limit of detection (LOD) was found to be 0.1 μM for the Bi2O3@MWCNTs nanomaterial and is excellent toward 4-NP. The present study has applications for reducing water pollution and for sorting out related issues.