Electrocatalysis最新文献

In the field of sustainable and renewable energy, developing highly active electrode materials for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a significant challenge. Herein, we have used novel M-type hexaferrites, SrCo_xNi_xFe_12−2xO₁₉ materials, prepared using sol-gel auto-combustion (SGAC) route, for water splitting, in which Co and Ni elements were used as doping materials. Six different compositions of hexaferrites were prepared by varying the concentrations of Co and Ni elements. The fabricated electrode materials were then well characterized by various advanced analytical tools such as XPS, PXRD, BET, FTIR, FE-SEM, and HR-TEM to evaluate their chemical composition, oxidation state, crystallinity, porosity, functional groups and morphology. These prepared electrocatalysts were used as electrode materials for OER and HER application. The rich heterostructural interfaces and unique morphology effectively accelerate the transition of electrons and expose highly active sites for chemical reactions. Among the prepared electrocatalysts, the one with x = 1.0 (SrNi6) shows better OER activity in terms of potential and kinetic activity. ECSA and EIS studies were also conducted to support the electrochemical observations, and the results were found to be consistent with the OER and HER results. Therefore, the fabricated electrocatalysts are suitable for electrochemical applications.

A new glass sample (BNiLi) was prepared by melt-quenching method. The physical nature of the glass sample was investigated via X-ray diffraction, while the atomic structure was studied via density and infrared spectroscopy. The existence of main structure units such as ({text{BO}}_{3}) and ({text{BO}}_{4}) was confirmed. Furthermore, the optical absorbance was measured, and the electronic transitions of nickel ions were revealed. Optical band gap energy was estimated for the BNiLi glass sample. The prepared BNiLi glass was used to modify a carbon paste electrode (CPE) with a polymer film of l-alanine (Ala). The obtained p-Ala@BNiLi/CPE was employed to determine linezolid (LIN) by cyclic voltammetric, linear sweep voltammetric, differential pulse voltammetric, and chronoamperometric methods. The proposed sensor achieves a low limit of detection (0.23 nM), good repeatability, and high stability. The fabricated sensor was applied to detect LIN in pharmaceutical and human serum samples.

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The elucidation of potential molecular structures and metabolites of pharmaceutical drugs remains a key area of research in medicinal chemistry, particularly due to drug-induced toxicity reactions. In this study, the electrochemical degradation of mefenamic acid (MFA) was conducted, leveraging biomimetic electron-transfer mechanisms. A carbon black (CB)–modified glassy carbon electrode (GCE) was employed as a biomimetic system to facilitate the in situ electrochemical conversion of MFA-drug into redox-active hydroxylated MFA metabolite (MFA-Redox). The chemically modified electrode (CME) demonstrated a surface-confined electronic feature of MFA-Redox, with a surface excess of 14.1 × 10⁻⁹ mol cm⁻² under physiological conditions. Various physicochemical and chemical characterization techniques, including liquid chromatography-mass spectrometry (LC–MS/MS) analysis, confirmed the hydroxylated metabolite of MFA (M_w = 305.05 g/mol). Furthermore, the CME was used for the mediated oxidation of thiol groups, using cysteine (CySH)—a biomarker for cellular redox balance in physiologically neutral pH—as a model compound. This resulted in a well-defined, diffusion-controlled oxidation peak current. The Michaelis–Menten (MM) enzymatic kinetics model was applied to describe the oxidation process, yielding key kinetic parameters: the MM rate constant (K_M) of 0.060 mM, the first-order catalytic rate constant (k_c) of 0.4 s⁻¹, and the heterogeneous electron-transfer rate constant (k'_ME) of 9.7 × 10⁻² cm s⁻¹. In a separate electroanalytical study, the performance of the CME for CySH detection was evaluated using amperometric i-t curves. The CME demonstrated a linear concentration range from 100 µM to 1 mM, with a sensitivity of 1.045 nA/µM and a detection limit of 3 µM. Importantly, the CME showed excellent selectivity, with no interference from uric acid, ascorbic acid, dopamine, glucose, and creatinine.

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Healthcare diagnostics and supplementary experimental research require electrochemical tools that are straightforward, inexpensive, delicate, quick, and precise. In addition to the previous reports of paracetamol sensors, we present an electrochemical sensor that customs differential pulse voltammetry (DPV) and cyclic voltammetry (CV) to determine the presence of nickel sulfide (NiS) on graphene oxide sheets (GO) (NiS@GO). Utilizing analytical methods, the composite surface morphology and structural characteristics were described. A substantial drop in overpotential was seen in the electrochemical investigation of the NiS@GO composite revised glassy carbon electrode (NiS@GO/GCE) owing to its substantial external part and high hauler agility, which demonstrated remarkable activity towards the oxidation of paracetamol (Para). Para electrochemical sensing was made more accessible by a diffusion-controlled oxidation process with an identical quantity of protons and electrons. From 3.3 µM to 125 µM the concentration of Para ornament linearly with the peak currents during the determination process 0.052 µM was the Para detection limit (3σ/S) sensitivity of the fabricated electrode was 12.14 µA µM⁻¹. In addition, the sensors demonstrated remarkable recovery with actual tablet samples over a month-long period with very little interference from common species. Commercial tablet samples demonstrate a noteworthy potential for wide-ranging applications in the electrochemical sector, with an acceptable recovery rate of 96.6 to 100.8%. An upfront, affordable quality monitoring system that can track the amount of para in tablets may be developed with the help of the suggested electrochemical sensor. Application investigations using the proposed sensor successfully detected Para in drug tabulations and biological materials.

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Preliminary experiments are reported to show quantitatively that hydrogen gas can be stored under triphasic conditions in wet nanoparticulate polymer of intrinsic microporosity (PIM-1) applied as a film to a platinum disk electrode surface. Based on chronoamperometric data, it is shown that the resulting triphasic interface is able to store hydrogen gas at apparent concentrations higher (3 orders of magnitude increase for an approx. 15 μm thick film with typically c_app,hydrogen = 80 mM; D_app,hydrogen = 1.2 × 10^–11 m²s⁻¹) than the known solubility of hydrogen gas in aqueous electrolyte (c_hydrogen = 0.08 mM; D_hydrogen = 5.0 × 10^–9 m²s⁻¹) at room temperature. Due to film roughness/heterogeneity, the apparent hydrogen concentration can only be estimated, but it increases with film thickness. At the same time the apparent diffusion coefficient is lowered considerably due to the molecularly rigid/glassy polymer host. The resulting modified electrode is investigated/proposed for energy storage applications with different amounts of PIM-1 nanoparticle deposits attached to the platinum surface.

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Graphene electrodes incorporated TiO₂/C-dots@NiO (G-TCN) nanocomposites have been successfully synthesized and investigated for their performance in detecting the pesticide diazinon (DZN). The synthesis begins with preparing a C-dots solution hydrothermally using tolaki citrus extract (Citrus sp.) as a precursor. The incorporation was continued hydrothermally between C-dots, Ni (II), and TiO₂ to obtain the TiO₂/C-dots@NiO (TCN) nanocomposites. The results of the morphological study illustrate that the TCN nanocomposite is composed of round particles with a uniform size between 180 and 200 nm. The XRD diffractogram pattern describes the overlapping interactions between the elements that make up the nanocomposites. The electrochemical performance in the Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ solution system illustrates the reversible redox reaction of G-TCN with a value of ∆E_p = 0.08 V. DZN detection showed superior results. Based on the cyclic voltammogram, DZN experienced a reduction at a potential of 0.65 V. The linearity test showed an LOD value of 0.09 μg/mL. In other tests, G-TCN showed good stability and reliability, with an RSD of 11.90% and 7.44%, respectively. The results reported in this work will be a reference for researchers in developing voltammetric sensors for pesticide residue detection.

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In this work, we proposed a novel 3D-printed manufactured electrode system. A project was developed and optimized, compatible with commercially available potetiostats. Additive manufacturing included the modification of the pseudo-reference electrode by electrodeposition of silver and its subsequent oxidation to the Ag/AgCl form. Then the system was tested using electrochemical techniques to check the application as a universal electroactive platform. As an example, we checked the detection of paracetamol as a common substance from non-steroidal anti-inflammatory drugs (NSAIDs). Finally, the system was compared to available commercial carbon electrodes, considering the screen-printed electrode (SPE no.1 and SPE no.2) and the glassy carbon electrode (GCE), showing higher sensitivity and linearity range compared to commercial screen-printed systems. The novelty of the proposed platform unveils a new way of common, simple, budget, and fast obtaining a universal electroactive platform for electrochemical research, keeping high-performance parameters.

Electrocatalytic reduction of CO₂ can convert CO₂ into a variety of carbon-based fuels and achieve carbon neutrality. Tin oxide (SnO₂) electrocatalytic materials have the advantages of low cost and low toxicity, and the electrocatalytic reduction of CO₂ to formic acid is highly selective. In this paper, Pd-doped SnO₂ nanoparticle materials were synthesized by flame spray pyrolysis and their properties for electrocatalytic reduction of CO₂ to formic acid were explored in a gas diffusion electrolytic cell. The results showed that the Pd/SnO₂ catalysts could improve the catalytic activity for the conversion of CO₂ to formate, and the most superior 0.5 Pd/SnO₂ showed a Faraday efficiency of 63% for formate at − 1.20 V vs. RHE and a current density of 90.59 mA^.cm⁻², which were 1.4 and 2.7 times higher than that of pure SnO₂, respectively. The modified catalyst grains were refined, and the charge transfer resistance at the catalyst interface was reduced, and the electrochemically active area was increased, generating more catalytically active sites and increasing the contact between CO₂, electrolyte, and electrode-catalyst. Density functional theory calculations showed that the doping of Pd element changed the local structure of SnO₂, and the Pd/SnO₂ surface was more favorable for the generation of the intermediate products ^*HCOO⁻ and formate as well as the inhibition of hydrogen precipitation, which was consistent with the experimental results.

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Herein, poly(methacrylic acid) (PMAA) and PMAA-g-carbon nanotube (CNT) (PMC) hydrogel composites were prepared using the redox polymerization method. PMAA and PMC hydrogel composites were coated with the Ru metal electrochemical deposition method to be used as electrocatalysts in water-splitting applications. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy–energy dispersive X-ray (SEM–EDX) and mapping, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the hydrogel composites. The electrochemical properties of these hydrogel composites were examined using techniques including linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. The activities of hydrogel composites against both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) were examined for water-splitting applications. The electrochemical results indicated that the Ru/PMC hydrogel composite exhibited high catalytic activity for both OER and HER in alkaline media.

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Protective-shell catalysts (particularly carbon-capped catalysts) may increase the durability of oxygen reduction catalysts, owing to their supposed anti-degradation effect. The mechanisms promoting this effect are still questioned and further scientific scrutiny is needed to better understand their underlying principle. In this paper, three carbon-capped PtNi/C catalysts with different extents of carbon cap graphitization were synthesized via a one-pot heat treatment. A precise electrochemical activation was applied, leading to similar intrinsic ORR activity than for a commercial Pt₃Ni/VC benchmark catalyst and larger activity than for the mother platinum nanoparticles supported on graphitized carbon (Pt/Gr.C) catalyst. To examine their robustness once fully activated, an aggressive accelerated stress test (AST) designed to emphasize Pt dissolution/redeposition, was performed and coupled with post mortem analyses. The carbon-capped catalyst with the most graphitized shell is able to withstand the AST: its Pt nanoparticle size is less affected than for uncapped catalysts, suggesting a positive action of the protective carbon cap.

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