International Journal of Chemical Kinetics最新文献

This study focuses on the green synthesis and characterization of silver nanoparticles (Ag-NPs) using Glycyrrhiza glabra root extract as a natural reducing agent. The antimicrobial potential of these nanoparticles was evaluated against a range of pathogens, including both bacteria and fungi. The synthesis process was initiated by adding Glycyrrhiza glabra root extract to a silver nitrate solution, resulting in a distinct color change from colorless to dark yellow, and eventually to black, signaling the formation of Ag-NPs. The formation and properties of the nanoparticles were further confirmed through UV–visible spectroscopy, which revealed a strong surface plasmon resonance peak at 421 nm, characteristic of Ag-NPs. X-ray diffraction (XRD) analysis showed that the nanoparticles possessed a face-centered cubic (FCC) structure, confirmed by the observation of well-defined Bragg reflections. Additionally, Energy Dispersive x-Ray Spectroscopy (EDX) and scanning electron microscopy (SEM) analyses were performed to assess the elemental composition and morphology of the synthesized nanoparticles. EDX results confirmed the presence of silver, while SEM images revealed the presence of nanoparticle aggregates, though no distinct morphology was observed. The antimicrobial activity of the synthesized Ag-NPs was tested against both Gram-positive and Gram-negative bacteria, with results indicating a significantly stronger antimicrobial effect against Gram-negative bacteria. These findings highlight the promising potential of green-synthesized Ag-NPs as effective antimicrobial agents, providing a sustainable and eco-friendly approach to nanoparticle synthesis with significant implications for various biomedical applications.

Although potassium (K) vanadyl phosphate fluoride (KVPO₄F) is considered one of the most promising cathode materials for K-ion batteries, its practical application is hindered by poor electronic conductivity and fluorine (F) loss during the synthesis process. In this work, a novel synthetic route is designed to realize the advanced KVPO₄F cathode material (denoted as KVPO₄F@C) by adopting in situ carbon coating approach initiated by isobutanol molecular intercalation, delivering two distinct characteristics of high F-containing and limited particle growth. On one hand, the as-generated in situ carbon coating layer enhances the electronic conductivity of KVPO₄F material and prevents the particle agglomeration during the calcination process. On the other hand, the as-introduced V–F–C bonds at the KVPO₄F/C interface realizes a high F-containing of KVPO₄F@C cathode material without large-scale F loss. As a result, the KVPO₄F@C cathode retains a high discharge capacity of 63.94 mAh g⁻¹ after 100 cycles at 2C as well as superior rate performance. This study highlights the critical role of the pathway to realize carbon coating approach in enhancing the electrochemical performance of KVPO₄F cathode.

Cost-effective techniques to building environmentally friendly dye-sensitized solar cells (DSSCs) are frequently investigated. As a result, ruthenium-based sensitizers and corrosive iodide/triiodide-based mediators are being replaced with nonharmful, relatively inexpensive, and effective alternatives. Chemistry, such as redox kinetics and mechanistic pathways, is therefore critical in determining the potential application of alternative substances. In this study, the kinetic insights of the electron transfer reaction between iron(III)/iron(II) based potential sensitizer/mediator pair in aqueous medium were investigated, and the reaction mechanism was proposed. Dicyanobis(2,2′-dipyridyl)iron(III); ([Fe^III(bpy)₂(CN)₂]⁺) oxidized hexacyanoferrate(II); ([Fe^II(CN)₆]⁴⁻) in aqueous medium. The reaction was electrochemically spontaneous and feasible. The kinetics of the reaction was probed under the pseudo-first-order condition by maintaining excess concentration of [Fe^II(CN)₆]⁴⁻ over [Fe^III(bpy)₂(CN)₂]⁺. The reaction was examined in the visible region by measuring the absorbance over time at constant ionic strength and room temperature. The reaction products were identified spectrophotometrically. A homemade instrumentation system was used to collect data at millisecond intervals due to the fast oxidation of [Fe^II(CN)₆]⁴⁻ by [Fe^III(bpy)₂(CN)₂]⁺ in water. The reaction proceeded in a defined sequence, starting with an observed overall zero order. This was succeeded by a general second order, identified due to the presence of various reactant-related species. The reaction parameters, including proton concentration, ionic strength, dielectric constant, and temperature, were optimized to determine the rate-determining step of the process. As a result, two rate laws were proposed for the redox reaction.

The gas phase reactions of the ozonolysis of three monoterpene alcohols: linalool, nerol, and citronellol, were investigated using a rigid atmospheric simulation chamber coupled to a proton transfer reaction-mass spectrometer (PTR-ToF-MS) to monitor the concentrations of the investigated compounds. Reaction rate constants were determined over the temperature range of 298–353 K at atmospheric pressure. Reaction rate constants (×10¹⁶ cm³ molecule⁻¹ s⁻¹) at 298 K are 3.12 ± 0.30 for linalool, 8.89 ± 0.90 for nerol, and 2.11 ± 0.10 for citronellol. The following Arrhenius expressions were established (cm³ molecule⁻¹ s⁻¹):$�\begin{array}{c}�����k_{�\text{linalool}�+�O_3�}�=��(�3.52�\pm �1.80�)��\times ��{10}^{�-�13�}�\exp ��(�-��(�2115�\pm �163�)��/�T�)����\\ �����k_{�}\end{array}$