Electrocatalysis最新文献

This article addresses the construction of a dopamine electrochemical sensor based on a molecularly imprinted polymer on carbon electrodes, for instance, glassy carbon and highly oriented pyrolytic graphite electrodes with the orientation of edge and basal plane by the formation of thiophene acetic acid-dopamine thin film using electropolymerization. The electrochemical deposition of Pt nanoparticles was then carried out at the modified electrode surface, followed by the extraction of dopamine as a template molecule from the generated layer was performed via elution brought on by chemicals. The variables that affect the performance of the imprinted polymer-based sensor, such as monomer-template ratio, immersion time, and the number of electropolymerization cycles, were examined and optimized. To confirm the changes in the oxidation peak current of DA and to investigate the electrochemical behavior of the MIP sensor, cyclic voltammetry, chronoamperometry, and differential pulse voltammetry (DPV) tests were performed. The differential pulse voltammetry studies revealed that, under ideal circumstances, the limit of detection values of the proposed MIP sensor decorated with Pt nanoparticles was found to be 14.40 nmol L⁻¹, 42.50 nmol L⁻¹, and 0.671 μmol L⁻¹ for glassy carbon, edge, and basal plane electrodes, respectively. In the presence of interferents with comparable structural chemicals, such as ascorbic acid, uric acid, glucose, o-phenylenediamine, and glycine, the proposed sensor exhibits noticeable selectivity. Dopamine analysis in a human fluid such as blood serum was conducted with success using the devised sensor, which was shown to possess impressive stability and reproducibility.

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Palladium coatings are deposited onto bulk silver, nickel and copper electrodes using galvanic exchange to study the oxygen reduction reaction (ORR) on those bimetallic electrodes. The electrodes prepared by galvanic replacement for 30 min in the Pd precursor bath are analysed by X-ray photoelectron spectroscopy and the surface morphology of all Pd coatings prepared onto Ag substrates are examined by scanning electron microscopy. The electrochemical tests show that specific activity of Pd on Ag for ORR in alkaline media increases with deposition time and specific activity of palladium on nickel reaches a plateau after 30 min of galvanic replacement.

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ORR was studied in 0.1 M KOH on Ag, Cu and Ni electrodes coated with palladium via galvanic replacement. Specific activity of Pd on Ag increased with each subsequent deposition step, whereas Pd on Ni reached maximum with 30 min.

Four molecular electrocatalysts based on cobalt complexes, CoT(X)PP (X = H (1), OH (2), CN (3), COOH (4)), were prepared from meso-tetra-p-X-phenylporphin (H₂T(X)PP, X = H, OH, CN, COOH) by reaction with cobalt acetate to be used for electrolytic proton or water reduction. The electrochemical properties and the corresponding catalytic activities of these four catalysts were investigated by cyclic voltammetry. Controlled potential electrolysis with gas chromatography analysis confirmed that the turn-over frequencies (TOF) per mol of catalyst per hour were 42.4, 38.6, 55.5, and 70.1 mol H₂ at an overpotential of 941.6 mV (in DMF) in the acetic acid solution containing catalyst. In neutral buffered aqueous solution (pH 7.0), these four molecular catalysts had TOF per mol of catalyst per hour of 352.53, 313.7, 473.4, and 714.6 mol H₂, respectively, with an overpotential of 837.6 mV, indicating that complex 4 had better activity than complexes 1, 2, and 3. The Faraday efficiencies of complexes 1-4 were 99.1, 99.6, 100.4, and 99.0% at 72 h of consecutive reduction on a glassy carbon electrode, respectively. These results indicate that the electronic properties of the ligands play a crucial role in determining the catalytic activity of the cobalt complex and are consistent with the phenomenon that the catalytic activity of the benzene porphyrins is significantly increased in the presence of electron-withdrawing groups, and the CoT(COOH)PP is the most active catalyst.

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Designing efficient and economical nano-catalysts in the development of electrochemical sensors has been a constant challenge. The design of core–shell nanoarrays using natural asphalt (NA) as the core has not been found in reports. In this report, for the first time, flower-like nanostructures were synthesized by joining nickel–cobalt double hydroxide nanosheets (NiCo-LDH NSs) on NA as a precursor. The synthesis of flower-like nanostructures, abbreviated as NA@NiCo-LDH NSs, was done by an easy and one-step hydrothermal method. NA has characteristics such as availability, cost-effectiveness, high surface area due to its porous structure, and good interaction with the surface of carbon electrodes due to its carbonaceous nature. In addition, the growth of NiCo-LDH NSs on the NA leads to the improvement of electrocatalytic properties, the creation of a larger specific surface area, available active sites, and an increase of contact between analyte and nanostructures. The performance of synthetic nanostructures in the electrochemical determination of deferiprone (DFN) was evaluated satisfactorily. DFN is the first oral iron chelator and the first drug for thalassemia patient treatment. This strategy has some advantages such as cost-effectiveness, portability, good linear range (0.5–2500 µM), and low detection limit (0.19 µM) in the DFN determination. The proposed strategy can be a way to develop new nanomaterials derived from NA with green chemistry in mind. In addition, it can be a way to enter NA-based nanomaterials into other applications.

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Flower-like nanostructures based on natural asphalt (NA) coated with nickel-cobalt double hydroxide nanosheets (NiCo-LDH NSs) have been synthesized and their application as a high-performance platform for the electrocatalytic oxidation of deferiprone has been studied.

Metal corrosion can cause massive economic losses and many safety hazards; thus, metal corrosion inhibition has been a major research direction worldwide. Among the many methods to stop metal corrosion, the addition of corrosion inhibitors is a common method. The use of amino acids as metal corrosion inhibitors not only has the advantage of being economical and efficient but also meets the long-term concept of being environmentally friendly. In this study, the effect on the corrosion behavior of a mild steel (X100 pipeline steel) in 1 M HCl containing the same concentration of the amino groups of cystine (Cys-Cys), cysteine (Cys), and glutamate (Glu) was investigated via density functional theory (DFT) and various characterization methods. These methods include the weightlessness method, electrochemical tests, scanning electron microscopy (SEM), and the contact angle test. The results show that the inhibition efficiency increased with increasing inhibitor concentration; Cys-Cys showed the best inhibition and Glu showed the poorest inhibition for X100 pipeline steel at the same amino group concentration. Furthermore, the results obtained from various characterization methods were generally consistent.

Electroanalytical performance of electrodeposited platinum nanoparticles (PtNPs), selenium nanoparticles (SeNPs), and tin oxide nanoparticles (SnO₂NPs) on the surface of bare fluorine-doped tin oxide (BFTO) (PtNPs-SeNPs-SnO₂NPs@BFTO) nanocomposite was used as an non-enzymatic electrochemical sensor towards detection of H₂O₂. The surface morphology and characterization of PtNPs-SeNPs-SnO₂NPs@BFTO was studied by field emission scanning electron microscopy (FESEM) and EDS mapping. The Morphology of PtNPs-SeNPs-SnO₂NPs@BFTO showed flower, spherical and irregular shapes by FESEM investigation. X-ray photoelectron spectroscopy was used to investigate the elemental composition of platinum, selenium, tin, oxygen, and fluorine on the PtNPs-SeNPs-SnO₂NPs@BFTO surface. The synthesized PtNPs-SeNPs-SnO₂NPs@BFTO electrochemical sensor was used for electro-catalytic detection of H₂O_2. The linear concentration range of the PtNPs-SeNPs-SnO₂NPs@BFTO was 0.01 to 54 mM, with a high sensitivity of 104.8 mA mM⁻¹ cm⁻² and a low detection limit of 0.01 mM. The interference study of PtNPs-SeNPs-SnO₂NPs@BFTO based sensors showed high selectivity towards H₂O₂ with interfering agents, including glucose (GU), ascorbic acid (AA), urea (UA), sucrose (SU), sodium chloride (SC), and sodium selenite (SS).

Study of the use of polymers with higher conductivity like polypyrrole, and polyaniline in the electrochemical insulin sensors can overcome the drawbacks arising from the ongoing use of non-conductive polymer membrane. Conductive polymer membranes maintain the positive properties of polymers, like improved stability, reproducibility, and even increase the current response of the prepared sensor toward insulin oxidation. Three different screen-printed electrodes modified with polyaniline, polypyrrole, or chitosan with electrochemically deposited nickel nanoparticles ensuring insulin oxidation were prepared. The electrode morphology was examined via SEM with EDX analysis. Also, the electroactive surface area and stability were determined by voltammetric methods. Based on the results, the SPCEs modified by polypyrrole and nickel nanoparticles were determined as the most appropriate for the insulin determination. The NiNPs-PPy-SPCE exhibited a linear range (500 nM–5 µM), a low-down limit of detection (38 nM), high sensitivity (3.98 µA/µM), and excellent result from insulin determination in real samples (human blood serum). The results confirmed the high potential of developed sensor for future research focused on detection of insulin via electrochemistry methods in clinical samples.

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This paper describes the development of a carbon paste electrode based on the butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([bmim] NTF2) ionic liquid and its modification with functionalized multiwalled carbon nanotubes (f-MWCNTs) /graphene (GR) nanocomposite film. The f-MWCNTs-GR modified carbon ionic liquid paste electrode (CILPE) was utilized for electrochemical determination of tyramine using the square wave voltammetry technique. The prepared electrochemical sensor exhibited an excellent electrocatalytic behavior for oxidation of tyramine molecules in solutions compared to the carbon paste electrode. This behavior can be assigned to the synergistic effect of carbon nanotubes, graphen and ionic liquid. The oxidation peak currents of tyramine were linear in the concentration range of 1–1000 μM with a detection limit of 0.5 μM. The obtained experimental results showed that the f-MWCNTs-GR/CILPE has a good selectivity toward tyramine molecules in the presence of interfering specious and it can be used confidently for measurement the concentration of tyramine in food and biological samples.

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Chlorpheniramine (CPM) is a widely used antihistamine drug that may be desirable to quantify in a variety of samples. We developed a CPM electrochemical sensor based on a composite of reduced graphene oxide (rGO) and silver nanoparticles (AgNPs) coated on a glassy carbon electrode (GCE). Sodium dodecyl sulfate (SDS) was used as a surfactant to prevent the aggregation of AgNPs. rGO and AgNPs were co-electrodeposited by cyclic voltammetry, varying the potential from -1.5 to 1.5 V vs. Ag/AgCl 3 M KCl. The electrochemical properties of the modified electrode were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The rGO/AgNPs/GCE showed excellent electrocatalytic activity for the oxidation of CPM. The anodic peak potential, measured using CV, was 0.78 V vs. Ag/AgCl in a carbonate-bicarbonate buffer of pH 10. The modified electrode exhibited a linear response for CPM concentrations between 10 and 300 μM, with a limit of detection of 4.2 μM. Several potentially interfering species, including ionic and organic compounds, did not have any significant effect on the CPM determination. This work thus describes a versatile sensor that could be applied to measure CPM in real samples.

In the development of ultrasensitive and selective sensors for heavy metal ions, the fabrication of titania-modified carbon paste electrodes with electrochemical sensing capabilities has received considerable attention. In this study, we investigated the facile preparation of the titania-modified carbon paste electrode and the determination of trace amounts of hazardous Hg(II), Cu(II), and Pb(II) ions by applying the square wave anodic stripping voltammetry method. The titania nanoparticles were characterized using various techniques such as size analyzer, XRD, and FTIR to determine their chemical properties. The experimental findings demonstrated that the titania nanoparticles were uniformly distributed in the graphite used to construct the modified electrode and had an average particle size of 85 nm in crystalline anatase form. Compared with the measurement results, the prepared sensor exhibited excellent sensing performance against Hg(II), Cu(II), and Pb(II) ions with a low detection limit of 15.26, 0.56, and 1.65 nM, respectively. In ternary solutions, their simultaneous determinations showed that the electrode is more sensitive to Hg(II) and Pb(II) ions, with detection limits of 8.32 and 0.25 nM, respectively. Consequently, the experimental results showed that the titania-modified carbon paste electrode is a promising sensor for the determination of hazardous Hg(II), Cu(II) and Pb(II) ions in sensor applications.

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