Electrocatalysis最新文献

Data-driven approaches have the potential to make a priori predictions. However, there are very few models that have been explored for the prediction of nanocomposite electrocatalysts under testing conditions. Here we report for the first time the parametric optimization coupled with data-driven approaches of efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline media. The parametric optimization suggests that the porous Ni- or Fe-based nitride composites, with combinatorial structures or thin films with average d-electrons between 5 and 8 and catalyst loading between 1 and 10 mg cm⁻² will exhibit the best OER activity. Machine learning classification of OER overpotential grades (η₁₀, overpotential at 10 mA cm⁻²) of transition metal oxynitrides (TMONs) and transition metal oxides (TMOs) is achieved using random forest (RF) and CatBoost algorithms. η₁₀ is classified as grade ‘A’ if η₁₀ < 351 mV, else grade ‘F’. We note that 80–85% of electrocatalysts containing nickel foam (NF) have been in grade A, implying NF is a prospective hindrance against true activity determination of the electrocatalyst but suitable for achieving grade ‘A’ electrocatalyst for electrolysers. RF and CatBoost models achieved an accuracy of 78.09% on the TMON dataset and RF model achieved 72.88% on the TMO dataset. This work aims to reduce the experimental time for the design and development of an electrocatalyst using a data-driven paradigm.

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In the present work, the four Fe-based structures were prepared from the phyto-synthetic approaches and their subsequent calcinations. The aqueous extracts of Salsola sp. and Heliotropium bacciferum plants were used as the bio-reductant and stabilizer in these approaches. The green synthesized structures were characterized using FT-IR, XRD, FESEM, EDX, and VSM techniques. The characterization results showed that calcination created a cubic γ-Fe₂O₃ phase with spherical morphology. The preparation of Pd-Fe composites was completed by reducing palladium ions on iron-containing samples using Salsola sp. aqueous extract. The effect of calcination and the type of extract used in the synthesis of Pd-Fe composites on their electrocatalytic activity towards the electrooxidation of ethylene glycol by voltammetry technique. The catalyst prepared with Salsola sp. (2.35 mA.cm⁻²) extract had better catalytic activity than the one Heliotropium bacciferum (1.67 mA.cm⁻²) for 0.28 M ethylene glycol oxidation. The catalytic activity of iron in the not-calcined form was higher than in the calcined due to the transformation in the electronic structure, confirmed by the change in the magnetic behavior of the sample. This work highlights the importance of green synthesis methodologies in electrochemistry applications. In summary, the main advantages of this work are the principles of green chemistry followed by an eco-friendly approach, sustainable resource utilization, cost-effectiveness, and enhanced catalytic properties.

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Herein, an electrochemical sensor based on antimony oxide/graphitic carbon nitride nanocomposite (Sb₂O₃/GCN) was applied for bisphenol A (BPA) electroanalysis in a water sample. This composite and its components were characterized with X-ray diffraction (XRD) spectroscopy, UV–visible spectroscopy, Raman spectroscopy, Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX). Electrochemical characterization of a pencil graphite electrode (PGE) modified with Sb₂O₃/GCN, Sb₂O₃ nanoparticles (Sb₂O₃ NPs) and graphitic carbon nitride (GCN) show that the Sb₂O₃/GCN modified pencil graphite electrode (PGE/Sb₂O₃/GCN) has the highest electroactive surface area and electronic conductivity. Theoretical calculation of the adsorption energies of BPA/GCN complex and its variants revealed that hydrogen bonding and π- π interaction between GCN and BPA contributed to the electrocatalytic oxidation of BPA at the proposed sensor. The limit of detection of BPA at PGE/Sb₂O₃/GCN was estimated to be 5.61 μM. The calibration curve depicting the changes in peak current with BPA concentration showed two linear ranges at 8–60 μM and 60–140 μM. Also, the proposed sensor offered a percentage recovery of 102.43% for BPA in spiked bottled water. These figures of merit as well as the outstanding selectivity, remarkable repeatability and good reproducibility of the proposed sensor are indications that PGE/Sb₂O₃/GCN is a useful analytical tool for BPA electroanalysis in water samples.

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Development of active electrocatalyst for CO₂ reduction to useful chemicals would be essential factor to achieve the carbon neutral society. The Co poly-4-vinyl-pyridine (P4VPy)/Ketjenblack (KB) activated thermally was found for an active electrocatalyst in the electroreduction of CO₂ with water by the solid-polymer-electrolyte, SPE, electrolysis cell. Various carbon supports were applied instead of KB. Contents of CoN₄C_x, CoO and Co⁰ compounds on activated electrocatalysts were determined by linear combination fitting, LCF, of X-ray absorption near edge structure, XANES. Pyrolysis of the catalyst precursor for activation was essential and kinds of carbon supports strongly influenced formation of the Co compounds. It was revealed that the content of CoN₄C_x related to the current efficiency of the CO formation and that of CoO and Co⁰ related the H₂ formation.

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Relation between Faraday efficiency to CO and content of CoN₄C_x

The transition to a hydrogen-based economy necessitates the development of sustainable and cost-effective electrocatalysts for green hydrogen production via water electrolysis. In this study, we report a novel cobalt-vanadium boride (CoVB) catalyst, which exhibits enhanced bifunctional activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media. CoVB was synthesized using a facile one-step chemical reduction method with varying vanadium concentrations, optimizing performance at a 3% vanadium content. Electrochemical analyses demonstrated that CoVB significantly outperformed cobalt boride (CoB), achieving an HER and OER overpotential (η₁₀) of 80 mV and 320 mV, respectively, comparable to noble metal benchmarks. Characterization results revealed that V plays a promoting role in inhibiting the growth of particles and agglomeration of particles, leading to an increase in surface area and producing unique mixed amorphous and crystalline structures in CoVB to enhance catalytic activity by increasing the number of active sites and conductivity across the interface. Furthermore, in two-electrode systems, the cell voltage of 1.66 V was needed to achieve 10 mA/cm² of current density with superior stability and reusability. Overall, the CoVB catalyst, a new candidate from the metal boride family, presents a promising alternative to precious metals for efficient and sustainable water-splitting in alkaline electrolyzers.

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The study focuses on improving methanol electrocatalytic oxidation (MOR) by optimizing platinum-based alloy electrocatalysts. Co–Ni-Pt ternary alloy nanoparticles were successfully deposited on carbon nanotubes via a chemical reduction method, forming a composite of Co–Ni-Pt nanoparticles/carbon nanotubes (Co–Ni-Pt NPs/CNTs). Various characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), special aberration corrected transmission electron microscopy (STEM), and X-ray photoelectron spectroscopy (XPS), were employed to analyze the morphology and structure of the material. The results illustrated a uniform distribution of Co–Ni-Pt alloy nanoparticles on the carbon nanotube surface. The catalytic performance of the Co–Ni-Pt NPs/CNTs composite materials was assessed using chronoamperometry (CA), linear sweep voltammetry (LSV), and cyclic voltammetry (CV). By adjusting the ratios of Co, Ni, and Pt, catalytic performance in MOR was improved. Among the Co–Ni-Pt NPs/CNTs composites tested, the Co_1.5Ni_1.5Pt₁ NPs /CNTs composite exhibited the highest catalytic activity, achieving a mass activity of 2537 mA mg⁻¹_Pt, outperforming that of commercial Pt/C catalysts by 1.37 times.

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In this study, we present a simple and sensitive carbon paste electrode embedded with Hyamine 1622-iodide/iodine for the simultaneous detection of ascorbic acid (AA), dopamine (DA), acetaminophen (AC), ibuprofen (IBP), and tyrosine (Tyr). Various electrochemical techniques, including cyclic and sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy, were employed to investigate the electrode’s performance. The optimized electrode demonstrated excellent sensitivity, with detection limits of 0.74, 0.46, 0.45, 0.52, and 0.44 µM for AA, DA, AC, IBP, and Tyr, respectively. Additionally, it exhibited a broad linear range: 2.4–960.0 µM, 1.5–800.0 µM, 1.5–800.0 µM, 1.7–960.0 µM, and 1.5–860.0 µM for the respective analytes. Further electrochemical analysis provided key parameters, including diffusion coefficients, apparent electrode surface area, heterogeneous rate constants, electrode surface coverage, electron transfer coefficients, and catalytic rate constants for the oxidation processes of the target analytes. The proposed electrode successfully detected AA, DA, AC, IBP, and Tyr in human biological samples, demonstrating good precision with relative standard deviations (RSD) of 2.1%–3.9% and recovery rates between 97 and 103%. The accuracy of the method was validated against a standard technique, confirming its reliability and robustness.

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In this study, we are reporting photocatalytic response of multiwall carbon nanotubes (MWCNTs)/cadmium oxide (CdO) nanocomposites. We dispersed MWCNT (1–5 wt%) into CdO system via sonication to obtain MWCNT/CdO nanocomposites. The methylene blue (MB) dye has been used as a photocatalytic probe to study response of degradation with respect to contact reaction time, effect of pH, temperature, and concentration of MWCNT into the CdO system. The optimum values are acquired at pH value of 6 and temperature range 50–60 °C for all composition of the catalysts. The intrinsic characteristics of resulting composites have been studied by X-ray diffraction, scanning electron microscopy, FT-IR analysis, and photoluminescence spectroscopy. It has been found that the as-prepared MWCNT/CdO nanocomposites possess dye absorptivity of 97.85%, significantly higher than the 64.85% observed for pristine CdO at a contact time of 75 min. Additionally, these nanocomposites exhibited an extended light absorption range and improved charge separation efficiency. The photodegradation of methylene blue shows significant enhancement in the reaction rate which reaches up to 0.058 min⁻¹ for the MWCNT/CdO composites, compared to 0.0189 min⁻¹ for the pristine CdO system.

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By employing ZrO₂ coupled barium oxide nanoparticles modified glassy carbon electrode (ZrO₂ coupled BaO/GCE), we create a novel platform to sense the environmental contaminant 2-nitrophenol. Using XRD, FTIR, and SEM, the phase formation of BaO and ZrO₂ coupled BaO nanomaterials was examined. In comparison to bare GCE, both ZrO₂ coupled BaO-modified GCE and pure BaO-modified GCE demonstrate strong electrocatalytic activity towards 2-nitrophenol. The ZrO₂ coupled BaO-modified sensing platform has good sensitivity for 2-nitrophenol measurement across a broad linear range of 0.2 to 60 µM, with a 0.09 µM detection limit at the lowest. Moreover, it exhibits strong selectivity towards significant interfering substances including 4-nitrophenol, 4-aminophenol, catechol, hydroquinone, etc. Good agreement is observed between the analytical application of the suggested sensor and actual real water sample analysis.

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Simultaneous electrochemical determination of three synthetic additive dyes (ponceau 4R (PON), its isomer amaranth (AMA), and tartrazine (TAR)) was performed with an electrochemical sensor based on a poly-sunset yellow and multi-walled carbon nanotube. In this work, sunset yellow was polymerized with a novel electropolymerization process. Field Emission Scanning Electron Microscopy (FESEM) demonstrates that the surface of the MWCNTs is covered with the sunset yellow polymer layer. The electrochemical activity of the sensor was verified by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and chronoamperometry. Under the optimized experimental conditions, the electrochemical determination of the PON, AMA, and TAR was carried out using differential-pulse voltammetry (DPV). The results showed low detection limits (LOD) of 0.11, 0.21, and 0.12 µM for PON, AMA, and TAR, respectively, with a linear range of 0.50–30.0 µM. The capability of the developed sensor for routine analysis of the real samples was demonstrated by the determination of PON, the AMA, and TAR in jelly-belly candy, jelly, and tap water.

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