Electrochemical Oxidation Of Nitrite Research Articles

Novel nitrogen‐rich anchored nickel (II) phthalocyanine with composite of multiwalled carbon nanotubes on modified glassy carbon electrode: Sensitive and selective electrocatalytic activity of nitrite

This work describes the synthesis of novel nickel tetra substituted 6‐bromobenzothiazole carboxamide nickel (II) phthalocyanine (NiTBBTCAPc) and confirmed by spectroscopic‐microscopic methods and as well as electrochemical analysis. The electrochemical oxidation of nitrite was studied on NiTBBTCAPc‐multiwalled carbon nanotube (MWCNTs)/glassy carbon electrode (GCE) due to its better electron transferring ability than bare GCE and NiTBBTCAPc/GCE. As there is acceleration in surface area of GCE by multiwalled carbon nanotubes, a cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric techniques utilized for nitrite sensor were developed. The sensor exhibited a fast response towards nitrite with a detection limit of 3.012 nM and a linear concentration range of 50–900 nM by the CV method. The fabricated sensor shows excellent electrocatalytic activity compared with the modified electrode with Pc with a composite of MWCNTs towards oxidation of nitrite. The NiTBBTCAPc‐MWCNTs/GCE shows good repeatability, stability, and high selectivity even in the presence of excess ascorbic acid (AA), dopamine (DA), uric acid (UA), paracetamol (PA), glucose, Pb (II), Cd (II), Ca (II), and Mg (II). Finally, for usage in practical applications, the modified electrode was employed to achieve quantitative detection of nitrite in drinking water and cabbage vegetable samples, respectively.

Musa sapientum mediated synthesis of Erbium doped copper oxide for the sensitive detection of nitrites and degradation of azo dye

The Musa sapientum mediated synthesis of Erbium doped Copper Oxide (Er-CuO) is used to modify the glassy carbon electrode (GCE) and has shown to be an electrochemical interface that is sensitive enough to detect nitrite. X-Ray Diffraction (XRD), Energy dispersive X-Ray (EDX), Scanning Electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and Brunauer–Emmett–Teller (BET) have been used to characterize the synthesized nanoparticle. In the electrochemical oxidation of nitrite, the Er-CuO electrode displayed greater oxidative current and lower overpotentials than the bare glassy carbon electrode. The recommended sensor showed linear response over the concentration range 10–180 μL with a limit of detection (LOD) of 7.74 μM and sensitivity of 0.00937 μA μM−1 cm−2. The synthesised Er-CuO could also degrade an azo dye-Methyl Red (MR) up to 98 per cent when exposed to visible light. The effects of different variables on photocatalysis, such as pH, dye concentration, and catalyst concentration, were investigated. Er-CuO may degrade 20 mg/L of MR up to 97 per cent at an ideal pH of 7.0 and 20 mg of catalyst concentration. The results demonstrate that Er-CuO is stable and can still degrade MR to 80 per cent even after 5 cycles. These stability test results demonstrate that Er-CuO is well stable for MR degradation under light and in nitrite electrochemical sensing.

Diazo-reaction based dual-mode colorimetric-electrochemical sensing of nitrite in pickled food.

Development of an effective and convenient sensor for sensitive detection of nitrites is of great concern since excessive amounts of nitrites can be harmful to both human health and the environment. In this work, Cu-MOF modified exfoliated graphite paper (EGP) was employed as a signal reporter to enable the visual and electrochemical dual-mode sensing of nitrites. Cu-MOFs were in situ synthesized on EGP, which exhibited an excellent oxidase enzyme-like activity to oxidize 3,3',5,5'-tetramethylbenzidine (TMB) into its oxidation product (oxTMB). The multi-layer structure and the superior electrical conductivity of EGP not only facilitated the loading of the Cu-MOF nanozyme for colorimetric sensing but also enabled its use as an underlying backbone to support electroanalysis. Based on the recognition of nitrite through a highly specific diazo reaction between nitrite and oxTMB, the addition of nitrite caused the colorimetric sensing solution to change color from blue to green, which allowed for the colorimetric sensing of nitrite with a limit of detection (LOD) of 8.5 × 10-6 mol L-1. Meanwhile, the Cu-MOF/EGP electrochemical platform was employed for ratiometric detection of nitrite based on the electrochemical oxidation of nitrite and TMB. Compared with the colorimetric mode, the electrochemical mode possessed higher sensitivity with a LOD of 5.4 × 10-7 mol L-1, indicating the high sensitivity and accuracy of the proposed dual-mode sensing strategy. Furthermore, the determination of nitrite in different pickled food samples is demonstrated.

Synthesis of Metal‐Free Nanoporous Carbon with Few‐Layer Graphene Electrocatalyst for Electrochemical NO2− Oxidation

AbstractHerein, electrochemical oxidation of nitrite (NO2−) is demonstrated using metal‐free and electrochemically highly stable nanoporous carbon (NC) system. The surface features of nanoporous carbon were studied using both spectroscopic and microscopic techniques including scanning electron microscope (SEM), transmission electron microscope (TEM) and is having layered mesh‐like features with a particle size of ∼20 to ∼100 nm. The as‐synthesized electrocatalyst is found to be more active towards electrooxidation of nitrite (NO2−) at considerably low onset potential of 0.58 V vs SCE with a significantly high current density of 5.2 μA/cm2 determined from linear sweep voltammetry (LSV), and cyclic voltammetry (CV) studies. The concentration and scan rate dependent studies confirm the nitrite oxidation is diffusion‐controlled process. The interfacial electron transfer features and parameters involved are determined by electrochemical impedance spectroscopic (EIS) studies. Moreover, current stability at a nitrite oxidation (0.58 V vs SCE) potential is also tested by chronoamperometric (i‐t) measurements and it demonstrates nanoporous carbon is having long term electrochemical stability. These studies establish the metal‐free nanoporous carbon as an efficient electrocatalyst for nitrite oxidation and will be good futuristic electrode material for other energy and environmental based electrochemical monitoring studies.

Enhanced Electrochemical NO2−Oxidation Reactions on Biomolecule Functionalised Graphene Oxide

AbstractHerein, electrochemical oxidation of nitrite (NO2−) is demonstrated using metal‐free, electrochemically highly stable, and selective biomolecule i. e. tyramine functionalized graphene oxide (GT) electrocatalyst for nitrite oxidation in phosphate buffer at pH‐7. The successful functionalization of a biomolecule on graphene is carried out by a simple chemical method. The surface features of biomolecule functionalized graphene oxide were studied by using both spectroscopic and microscopic techniques including scanning electron microscope (SEM) which shows wrinkled and folded structures having a thickness of ∼20 nm corresponding to a few layer of graphene. Moreover, their structural analysis was carried out using X‐ray photoelectron spectroscopy nitrogen band at peak position of ∼400 eV reveals biomolecule functionalization, Fourier‐transform infrared spectroscopy (FTIR) reveals significant peak at 1580 cm−1 corresponding to amine functionalization, Raman Spectroscopy reveals enhanced ID/IG ratio as compared to GO. The electrochemical surface area (ECSA) found tobe 3.60 cm2. The as‐synthesized electrocatalyst is found to be more active towards electro‐oxidation of nitrite (NO2−) at a low onset potential of 0.6 V vs saturated calomel electrode (SCE) from linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. Moreover, its current stability at a given potential is also tested by chronoamperometric (i‐t) measurements within a concentration range of 0 μM to 7 μM and is having long term good electrochemical stability at an onset potential of 0.6 V vs SCE. The onset potential of GT was 0.6 V vs SCE, the limit of detection (LOD) 0.933 μM and high current density 21 mA cm−2 as compared to GO 8.7 mA cm−2. Considering above perspectives, our findings emphasizes the importance of biomolecule functionalised GO is the best electrocatalyst for electro‐oxidation of nitrites, which is one of the important species for environmental remediation.

Electropolymerized melamine for simultaneous determination of nitrite and tartrazine

Poly(melamine) (PMel) was synthesized via the electropolymerization of melamine monomer, which was then characterized by field-emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The possible polymerization mechanisms of melamine were also revealed by FT-IR spectroscopy and UV–Vis spectroscopy. Next, the PMel modified GCE (PMel/GCE) was used for the simultaneous determination of nitrite (NO2−) and tartrazine, and the parameters were optimized. The kinetic study showed that the electrochemical oxidation of nitrite and tartrazine at the surface of PMel/GCE is a typical surface-controlled electrode process. Under the optimun conditions, the developed sensor outperformed those previously reported, and it also exhibited high selectivity and reproducibility. Finally, the PMel/GCE was used for the simultaneous determination of nitrite and tartrazine in foodstuffs, and the results indicated that the proposed sensor could be a promising candidate for accurate determination of nitrite and tartrazine in real food samples.

Highly sensitive electrochemical analysis of tunnel structured MnO2 nanoparticle-based sensors on the oxidation of nitrite

Three MnO2 nanoparticles with different tunnel structures, α-, β-, and γ-MnO2, were synthesized and characterized. We demonstrated and compared their capabilities on the electrochemical oxidation of nitrite, providing a new perspective for MnO2 or MnO2 based materials on sensing application. α-MnO2 exhibited higher electrochemical reactivity than β- or γ-MnO2, which was ascribed to its higher conductivity, more exposure to MnO6 edges, longer average MnO bond length, and lower Mn average oxidation state(AOS). We hereby reported the first α-MnO2 nanoparticle-based electrochemical sensor for nitrite sensing. A highly controlled micro-plotter was used to deposit the MnO2 nanoparticles for the sensor fabrication, providing a micro-pattern of the sensing surface area of MnO2 and ensuring the reproducibility and sensitivity of this MnO2 based sensor. Using differential pulse voltammetry, a detection range of 10–800 μM of nitrite was accomplished along with a sensitivity of 17.1 μA μM−1 and a detection limit of 0.5 μM.

A glassy carbon electrode modified with poly(3,4-ethylenedioxythiophene) doped with nano-sized hydroxyapatite for amperometric determination of nitrite

A conducting polymer composite was prepared from nano-sized hydroxyaptite (nHAp) doped into poly(3,4-ethylenedioxythiophene) (PEDOT) and then electrodeposited on a glassy carbon electrode (GCE). The nHAp carries carboxy groups and therefore is negatively charged at moderate pH value. When doped into PEDOT (PEDOT-nHAp), it forms a uniform and stable film that exhibits low electrochemical impedance, a large specific surface, and high activity toward the electrochemical oxidation of nitrite. Under optimized conditions and at a relatively low working potential of 0.78 V (vs. SCE), the modified GCE exhibited a linear amperometric response in the 0.25 μM to 1.05 mM nitrite concentration range, and the limit of detection is as low as 83 nM.

Electrochemical Detection of Nitrite Using Glassy Carbon Electrode Modified with Silver Nanospheres (AgNS) Obtained by Green Synthesis Using Pre‐hydrolysed Liquor

AbstractSilver nanospheres (AgNS) with SPR band ∼417 nm was synthesized by Green synthesis, using a pre‐hydrolysed liquor (PHL) of Nilgiri wood without any pretreatment. The synthesis was carried out at room temperature and was complete within three hours. The reduction and stabilization of silver is brought about by hemicelluloses present in the pre‐hydrolysed liquor. Electrochemical oxidation of nitrite on glassy carbon electrode (GCE) modified with the AgNS in 0.1 M phosphate buffer solution (PBS) of pH 7.0 was found to occur at 0.86 V with respect to Ag/AgCl. Electrochemical sensing experiments with AgNS/GCE showed a linear range of detection between 0.1 to 8 μM, with detection limit of 0.031 μM and a sensitivity of 580 μA mM−1cm−2.

Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

The electrochemical sensor based on electrochemical oxidation of nitrite on metalloporphyrin–graphene modified glassy carbon electrode

In this study, 5-(4-aminophenyl)-10,15,20-triphenylporphyrin]Mn(iii) (MnNH2TPP) and graphene oxide (GO) composite materials (GO–MnNH2TPP) were successfully used to modify a glassy carbon electrode (GC) by the drop casting method.

Nitrite Oxidation with Copper-Cobalt Nanoparticles on Carbon Nanotubes Doped Conducting Polymer PEDOT Composite.

Copper-cobalt bimetal nanoparticles (Cu-Co) have been electrochemically prepared on glassy carbon electrodes (GCEs), which were electrodeposited with conducting polymer nanocomposites of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with carbon nanotubes (CNTs). Owing to their good conductivity, high mechanical strength, and large surface area, the PEDOT/CNTs composites offered excellent substrates for the electrochemical deposition of Cu-Co nanoparticles. As a result of their nanostructure and the synergic effect between Cu and Co, the Cu-Co/PEDOT/CNTs composites exhibited significantly enhanced catalytic activity towards the electrochemical oxidation of nitrite. Under optimized conditions, the nanocomposite-modified electrodes had a fast response time within 2 s and a linear range from 0.5 to 430 μm for the detection of nitrite, with a detection limit of 60 nm. Moreover, the Cu-Co/PEDOT/CNTs composites were highly stable, and the prepared nitrite sensors could retain more than 96 % of their initial response after 30 days.

Facile synthesis of TiO2-functionalized graphene nanosheet-supported Ag catalyst and its electrochemical oxidation of nitrite

A new sandwich structure nanocomposite of Ag nanoparticles supported on TiO2-functionalized graphene nanosheet was synthesized, involving a simple chemical reduction of GO using TiCl3 as reducing agent and the in situ formation of TiO2 as linker between r-GO and Ag. Based on the Ag/TiO2/r-GO hybrid material, a novel electrochemical sensor for the determination of nitrite was constructed. The morphology and composition of the nanocomposite were characterized by transmission electron microscope and UV–vis absorption spectra. Electrochemical investigation indicated that Ag/TiO2/r-GO modified electrode exhibited excellent electrocatalytic performance for the oxidation of nitrite. The sensor showed a wide linear range from 1.0 µM to 1.1 mM, with the detection limit of 0.4 µM, the sensitivity of 112.0 μA mM−1 cm−2. Additionally, the proposed method was successfully applied to the detection of nitrite in water samples with obtained satisfactory results.

Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemical approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene.

Electrocatalytic Oxidation and Determination of Nitrite at Multi‐walled Carbon Nanotubes Modified Carbon Ceramic Electrode

AbstractIn the present work, the electrochemical oxidation of nitrite on carbon ceramic electrode (CCE) modified with multi‐walled carbon nanotubes (MWCNTs) was investigated. The modified electrode exhibited catalytic activity toward the electrooxidation of nitrite. Experimental parameters such as solution pH, scan rate, concentration of nitrite and nanotubes amount were studied. It was shown nitrite can be determined by differential pulse voltammetry (DPV) and hydrodynamic amperometry (HA) using the modified electrode. Under the optimized conditions the calibration plots are linear in the concentration ranges of 15‐220 and 50‐3000 μM with limit of detections of 4.74 and 35.8 μM for DPV and HA, respectively. The modified electrode was successfully applied for analysis of nitrite in spinach sample. The results were favorbly compared to those obtained by UV‐Visible spectrophotometric method. The results of the analysis suggest that the proposed method has promise for the routine determination of nitrite in the examined products.

Electrochemical oxidation of nitrite: Kinetic, mechanistic and analytical study by square wave voltammetry

The voltammetric determination of nitrite is in principle a very competitive method by virtue of being fast, easy to apply, economical and portable. In order to optimize the experimental conditions for the analytical determination it is essential to understand the reaction scheme and kinetics of the redox system. With this purpose, in this paper square wave voltammetry is employed to examine the electro-oxidation of nitrite. The reaction mechanism and electrode kinetics are investigated, pointing out the effects of the solution pH, the electrode material (glassy carbon, edge plane pyrolytic graphite and gold) and the supporting electrolyte. A second order catalytic mechanism justifies the experimental results, with the nitrite being regenerated by disproportionation of the electrogenerated NO2 with a rate constant kdisp=(2.0±0.1)×106M−1s−1. The electrode reaction is found to be reversible on gold macroelectrodes and much slower on carbon based electrodes with blocking effect due to the presence of perchlorate anions.

Electrochemical oxidation of nitrite on nanodiamond powder electrode

Nanodiamond (ND) powder electrodes were fabricated and the electrochemical properties were investigated in the solution containing nitrite in this article. This electrode exhibits substantial catalytic ability toward the oxidation of nitrite anions. The electrochemical oxidation mechanism of nitrite on the ND powder electrode is discussed. The oxidation of NaNO 2 is a two-electron transfer process. The electrode reaction rate constant k is estimated to be 2.013 × 10 −4 cm/s and (1 − α) n α is 0.1643. The peak current increases linearly with the rising of the concentration of NaNO 2.

Electrochemical Oxidation of Nitrite and the Oxidation and Reduction of NO2 in the Room Temperature Ionic Liquid [C2mim][NTf2

The electrochemical oxidation of potassium nitrite has been studied in the room temperature ionic liquid (RTIL) [C2mim][NTf2] by cyclic voltammetry at platinum electrodes. A chemically irreversible oxidation peak was observed, and a solubility of 7.5(+/-0.5) mM and diffusion coefficient of 2.0(+/-0.2)x10(-11) m2 s(-1) were calculated from potential step chronoamperometry on the microdisk electrode. A second, and sometimes third, oxidation peak was also observed when the anodic limit was extended, and these were provisionally assigned to the oxidation of nitrogen dioxide (NO2) and nitrate (NO3-), respectively. The electrochemical oxidation of nitrogen dioxide gas (NO2) was also studied by cyclic voltammetry in [C2mim][NTf2] on Pt electrodes of various size, giving a solubility of ca. 51(+/-0.2) mM and diffusion coefficient of 1.6(+/-0.05)x10(-10) m2 s(-1) (at 25 degrees C). It is likely that NO2 exists predominantly as its dimer, N2O4, at room temperature. The oxidation mechanism follows a CE process, which involves the initial dissociation of the dimer to the monomer, followed by a one-electron oxidation. A second, larger oxidation peak was observed at more positive potentials and is thought to be the direct oxidation of N2O4. In addition to understanding the mechanisms of NO2- and NO2 oxidations, this work has implications in the electrochemical detection of nitrite ions and of NO2 gas in RTIL media, the latter which may be of particular use in gas sensing.

A Novel Nitrite Amperometric Sensor and Its Application in Food Analysis

AbstractBrilliant cresyl blue (BCB), one of the phenoxazine dyes, was electropolymerized on the glassy carbon (GC) electrode. The resulting electroactive polymer film could provide more active sites for anodic oxidation of nitrite, based on which a novel nitrite sensor was developed. The optimized fabrication and sensing conditions were investigated. This sensor exhibited high sensitivity, low detection limit and simple operation toward the electrochemical oxidation of nitrite. It was successfully applied to the determination of nitrite in some food samples and the results were consistent with those obtained with the standard spectrophotometric procedure.

Development of a novel nitrite amperometric sensor based on poly(toluidine blue) film electrode

A novel sensor for the determination of nitrite anion ( % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX % garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz % aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq % Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq % Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca % qGobGaae4tamaaBaaaleaacaqGYaaabeaakmaaCaaaleqabaGaeyOe % I0caaaaa!3B39! $$ {\text{NO}}_{{\text{2}}} ^{ - } $$ ) was fabricated by electrodeposition of toluidine blue. The sensor exhibited good catalytic activity toward the electrochemical oxidation of nitrite. Amperometry was carried out to determine the concentration of % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX % garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz % aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq % Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq % Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca % qGobGaae4tamaaBaaaleaacaqGYaaabeaakmaaCaaaleqabaGaeyOe % I0caaaaa!3B39! $$ {\text{NO}}_{{\text{2}}} ^{ - } $$ . A linear response in the range from 1.0×10−7 to 1.52×10−5 M with a substantially low detection limit of 5×10−8 M (S/N=3) was obtained. The proposed sensor had a feature of high sensitivity of 4.7×105 μA M−1 cm−2. The possible interference from several common ions was tested. This sensor was applied to the amperometric determination of nitrite in food samples, and the results were consistent with those obtained with the standard spectrophotometric procedure.