Electrocatalysis最新文献

A novel electrochemical nanosensor was established for the simultaneous measurement of dopamine (DA) and acetaminophen (AC). The nanosensor was achieved by modification of carbon paste electrode (CPE) by Ag nanoparticle, polyoxometalate, reduced graphene oxide (Ag@POM@rGO), and ionic liquid (IL). The electrochemical behaviors of DA and AC were evaluated by Ag@POM@rGO-IL/CPE and various electrochemical methods. Design-Expert software by response surface methodology (RSM) approach was utilized to consider the interaction between the different factors. The best electrochemical response was attained with 0.01 g of IL and 0.04 g of Ag@POM@rGO in the modified electrode, phosphate buffer solution (0.1 M, pH 7.0), and a sweep rate of 0.07 V s⁻¹. In the optimum situation, the calibration curves for DA and AC were achieved in a square wave voltammetry (SWV) manner, and linear dynamic ranges (LDR) were obtained to be 0.05–115.04 µM and 0.1–137.90 µM for DA and AC, respectively. The limit of detection (LOD) was attained to be 17.0 for DA and 37.0 nM for AC. The Ag@POM@rGO-IL/CPE showed good stability, productivity and repeatability, and advanced recovery, and it has a little price and low background current. Also, the usage of this nanosensor was studied by measuring the DA and AC in the human plasma by means of worthy recovery. This technique is easy, rapid, and cheap and can be utilized as a significant device in the quantitative analysis of the medicinal product.

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Among various chalcogenide materials, transition metal sulfides are known to be effective catalysts for the electrochemical hydrogen evolution reaction (HER). In particular, Ni-Co-S is a promising material for the next generation of non-precious metal HER catalysts due to its excellent HER activity in neutral pH solutions. Ni-Co-S is also advantageous in large-scale applications, as it enables relatively simple catalytic synthesis through electrodeposition. In this study, we employed a new S precursor, 2,5-dimercapto-1,3,4-thiadiazole (DMTD), for the electrodeposition of Ni-Co-S, instead of the conventional S precursor, thiourea (TU). Ni-Co-S synthesized with DMTD (Ni-Co-S_DMTD) showed enhanced HER activity at neutral pH compared to that synthesized with TU (Ni-Co-S_TU). It has been found that this improvement in activity is due to the large surface area and high S content of Ni-Co-S_DMTD. The S content and HER activity of Ni-Co-S_DMTD depend on the concentration of DMTD. At the optimal DMTD concentration (12 mM), Ni-Co-S_DMTD exhibited an overpotential of 303 mV at a current density of 10 mA cm^− 2 and a Tafel slope of 99 mV dec^− 1 in a phosphate buffer solution (pH 7.4).

Graphical Abstract

Manganese oxide based materials are considered as alternate non-noble metal electrocatalysts for oxygen reduction reaction (ORR). These materials possess rich redox chemistry and can decompose hydrogen peroxide disproportionately to drive the oxygen reduction towards efficient 4-electron pathway. In this work, a set of MnO nanostructures supported on activated charcoal (MnO/C) with varying MnO loadings are prepared by ball milling followed by in-situ pyrolysis. The MnO/C composites are tested for ORR activity by employing cyclic voltammetry and linear sweep voltammetry using rotating-ring disk electrode (RRDE) in 0.1 M KOH. The results indicate that the ORR activity as well as catalytic pathways are sensitive to MnO loading. The ORR activities of the composites follow volcano type relationship with the quantity of MnO loadings. The role of MnO loading on surface morphology, hydrophilicity, electrochemical double layer capacitance (C_dl) and electrochemical active surface area (ECSA) of the composites has been investigated and correlated with ORR activity. Among the MnO electroctalysts studied, 18 wt% MnO loaded sample showed the highest activity, close to that of standard Pt/C, with onset potential of 1.02 V vs. RHE and 3.48 mA cm^-2 limiting disk current in RRDE at 0.2 V. This electrocatalyst also preferred 4-electron reduction pathway in ORR and produced least amount of hydrogen peroxide. No hydrophilicity effect is found on the ORR activity of MnO/C electrocatalysts.

As a representative anodic reaction, the oxygen evolution reaction (OER) is often combined with hydrogen evolution, carbon dioxide reduction, and other cathodic reactions. Bimetallic selenides can satisfy the requirement of efficiency and economy for OER. However, the OER performance of Fe-Co-Se is less than satisfactory, restricted by the limited inherent active sites. Therefore, by doping P into Fe-Co-Se, the electron density and mass transfer were successfully adjusted. The 3D dandelion-like flower Fe-Co-Se-P/CC showed η₁₀ of 210 mV and the 45.3 mV dec⁻¹ Tafel slope better than Fe-Co-Se/CC and RuO₂. Experimental investigations demonstrated that outstanding OER activity was ascribed to the double modulation influences of P dopant both in electron environment and morphology which could not only improve conductivity but also enrich catalytic reactive sites. This work presents another choice for the design of a transition metal OER catalyzer and propels the development of electrocatalytic oxygen production to higher efficiency and lower cost.

Graphical Abstract

3D dandelion-like flowers Fe-Co-Se-P structure anchored on carbon cloth has been firstly synthesized as economy and efficient OER electrocatalyst, which displays outstanding catalytic perform ance (equipped with 210 mV low overpotential at η₁₀) and stability benefited from the double modulation effect of P doping on the electronic environment and morphology.

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.

Graphical Abstract

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.