Radiation Chemistry Reveals the Reaction Mechanisms Involved in the Reduction of Vinylene Carbonate in the Solid Electrolyte Interphase of Lithium-Ion Batteries.

A safe and efficient lithium-ion battery requires including an additive in the electrolyte. Among the additives used, vinylene carbonate (VC) is particularly interesting, because it leads to the formation of a stable and protective solid electrolyte interphase (SEI) on the negative electrode. However, the reduction behavior of VC, resulting in polymer formation, is complex, and many questions remain as to the corresponding reaction mechanisms.

Picosecond Pulse Radiolysis Observation of the Formation and Spur Kinetics of Hydrated Electrons in Sodium Dodecyl Sulfate-Water-Cyclohexane-Hexanol Quaternary Microemulsions.

The observation of electron transfer and solvation processes in liquid-liquid multiphase systems is of great challenge, especially at the interface. In this study, the formation and spur kinetics of hydrated electrons (e) were investigated in sodium dodecyl sulfate-water-cyclohexane-hexanol microemulsions with ω values (/) from 18 to 48 using picosecond pulse radiolysis coupled with pulse-probe UV-vis spectroscopy. Interestingly, a relatively slow formation of e was observed, corresponding to the electron transfer from the oil phase to water pools.

Role of Oxide-Derived Cu on the Initial Elementary Reaction Intermediate During Catalytic CO Reduction.

The catalytic role of oxide-derived Cu (OD-Cu) in promoting CO reduction (COR) to C products has been appreciated for decades. However, the dynamic evolution of the surface oxidation states, together with their real correlation to the binding of reaction intermediates, remains unclear due to technical challenges. Here, we show the time-resolved spectroscopic signatures of key OD-Cu-CO intermediates during catalytic CO reduction through one electron transfer from nanoseconds to seconds time scale.

Direct Observation of the Reactivity of Electrons toward Gold Nanoparticles in Aqueous Solution.

The catalytic activity of gold nanoparticles (AuNPs) has been widely acknowledged; however, Au NPs are considered to be highly inert as radiosensitizers in biological systems. This apparent discrepancy across different fields complicates the understanding of their interfacial reactivity, particularly in terms of electron transfer reactions. Here, we employ pulse radiolysis to determine the rate constants for the reactions of electrons with AuNPs in aqueous solution.

Radiation-Induced Synthesis and Superparamagnetic Properties of Ferrite FeO Nanoparticles.

Ultra-small magnetic FeO nanoparticles are successfully synthesized in basic solutions by using the radiolytic method of the partial reduction in Fe in the presence of poly-acrylate (PA), or by using the coprecipitation method of Fe and Fe salts in the presence of PA. The optical, structural, and magnetic properties of the nanoparticles were examined using UV-Vis absorption spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and SQUID magnetization measurements. The HRTEM and XRD analysis confirmed the formation of ultra-small magnetite nanoparticles in a spinel structure, with a smaller size for radiation-induced particles coated by PA (5.

Overlooked Activation Role of Sulfite in Accelerating Hydrated Electron Treatment of Perfluorosulfonates.

Photoexcitation of sulfite (SO) is often used to generate hydrated electrons (e) in processes to degrade perfluoroalkyl and polyfluoroalkyl substances (PFASs). Conventional consensus discourages the utilization of SO concentrations exceeding 10 mM for effective defluorination. This has hindered our understanding of SO chemistry beyond its electron photogeneration properties.

Reactivity of quasi-free electrons toward N and its impact on H formation mechanism in water radiolysis.

Picosecond pulse radiolysis measurements were employed to assess the effectiveness of N in scavenging quasi-free electrons in aqueous solutions. The absorption spectra of hydrated electrons were recorded within a 100 ps timeframe across four distinct solutions with N concentrations of 0.5, 1, 2, and 5 M in water.

Direct time-resolved observation of surface-bound carbon dioxide radical anions on metallic nanocatalysts.

Time-resolved identification of surface-bound intermediates on metallic nanocatalysts is imperative to develop an accurate understanding of the elementary steps of CO reduction. Direct observation on initial electron transfer to CO to form surface-bound CO radicals is lacking due to the technical challenges. Here, we use picosecond pulse radiolysis to generate CO via aqueous electron attachment and observe the stabilization processes toward well-defined nanoscale metallic sites.

Observation of Nanoconfinement Effect on the Kinetics of Hydrated Electron in the Nanoscale Water Pools of Water-AOT-Cyclohexane Microemulsions by Picosecond Pulse Radiolysis.

The decay kinetics of the hydrated electron (e) in aerosol OT (AOT)-based ternary microemulsions with pool sizes ranging from 0.34 to 4.85 nm were studied using picosecond pulse radiolysis coupled with transient absorption UV-vis spectroscopy.

Selective CO reduction to CHOH over atomic dual-metal sites embedded in a metal-organic framework with high-energy radiation.

The efficient use of renewable X/γ-rays or accelerated electrons for chemical transformation of CO and water to fuels holds promise for a carbon-neutral economy; however, such processes are challenging to implement and require the assistance of catalysts capable of sensitizing secondary electron scattering and providing active metal sites to bind intermediates. Here we show atomic Cu-Ni dual-metal sites embedded in a metal-organic framework enable efficient and selective CHOH production (~98%) over multiple irradiated cycles. The usage of practical electron-beam irradiation (200 keV; 40 kGy min) with a cost-effective hydroxyl radical scavenger promotes CHOH production rate to 0.

Predicting Degradation Mechanisms in Lithium Bistriflimide "Water-In-Salt" Electrolytes For Aqueous Batteries.

Aqueous solutions are crucial to most domains in biology and chemistry, including in energy fields such as catalysis and batteries. Water-in-salt electrolytes (WISEs), which extend the stability of aqueous electrolytes in rechargeable batteries, are one example. While the hype for WISEs is huge, commercial WISE-based rechargeable batteries are still far from reality, and there remain several fundamental knowledge gaps such as those related to their long-term reactivity and stability.

Unveiling the Intimate Mechanism of the Crocin Antioxidant Properties by Radiolytic Analysis and Molecular Simulations.

The successive steps of the oxidation mechanism of crocin, a major compound of saffron, by the free OH radical are investigated by pulse radiolysis, steady-state (gamma) radiolysis methods, and molecular simulations. The optical absorption properties of the transient species and their reaction rate constants are determined. The absorption spectrum of the oxidized radical of crocin resulting from the H-abstraction presents a maximum of 678 nm and a band of 441 nm, almost as intense as that of crocin.

Reactivity of presolvated and solvated electrons with CO in water up to 118 bar at 298 and 308 K.

The reactivity of electrons in the CO-water system was evaluated through picosecond electron pulse radiolysis at different gas pressures (ranging from 1 to 118 bar) and temperatures (25 and 35 °C) coupled with UV-vis transient spectroscopy. A custom-made spectroscopic cell was utilized for these experiments, which allowed for regulation of temperature and pressure. The scavenging of electrons was measured directly at gas pressures even in the supercritical state, and the results showed a non-monotonic dependence of electron reactivity with CO concentration, in agreement with the changing molar concentration of CO in water under varying pressure.

Radiolytic Water Splitting Sensitized by Nanoscale Metal-Organic Frameworks.

High-energy radiation that is compatible with renewable energy sources enables direct H production from water for fuels; however, the challenge is to convert it as efficiently as possible, and the existing strategies have limited success. Herein, we report the use of Zr/Hf-based nanoscale UiO-66 metal-organic frameworks as highly effective and stable radiation sensitizers for purified and natural water splitting under γ-ray irradiation. Scavenging and pulse radiolysis experiments with Monte Carlo simulations show that the combination of 3D arrays of ultrasmall metal-oxo clusters and high porosity affords unprecedented effective scattering between secondary electrons and confined water, generating increased precursors of solvated electrons and excited states of water, which are the main species responsible for H production enhancement.

Pathways of the Dissociative Electron Attachment Observed in 5- and 6-Azidomethyluracil Nucleosides: Nitrogen (N) Elimination vs Azide Anion (N) Elimination.

5-Azidomethyl-2'-deoxyuridine (5-AmdU, ) has been successfully employed for the metabolic labeling of DNA and fluorescent imaging of live cells. 5-AmdU also demonstrated significant radiosensitization in breast cancer cells via site-specific nitrogen-centered radical (π-aminyl (U-5-CH-NH), , and σ-iminyl (U-5-CH═N), ) formation. This work shows that these nitrogen-centered radicals are not formed via the reduction of the azido group in 6-azidomethyluridine (6-AmU, ).

Application of Geant4-DNA for simulating water radiolysis induced by Auger electron-emitting radionuclides.

Auger-emitting radionuclides have potential application in targeted radiotherapy, particularly for metastatic cancers. This possibility, especially, is stemmed from their characteristic short-range (a few μm) in biological systems allowing localization of high dose within small tumours. To explore this potential application, a Geant4 Monte Carlo toolkit has been employed to simulate the energy deposition of different radionuclides in a water model.

Modulation of the Directionality of Hole Transfer between the Base and the Sugar-Phosphate Backbone in DNA with the Number of Sulfur Atoms in the Phosphate Group.

This work shows that S atom substitution in phosphate controls the directionality of hole transfer processes between the base and sugar-phosphate backbone in DNA systems. The investigation combines synthesis, electron spin resonance (ESR) studies in supercooled homogeneous solution, pulse radiolysis in aqueous solution at ambient temperature, and density functional theory (DFT) calculations of in-house synthesized model compound dimethylphosphorothioate (DMTP(O)═S) and nucleotide (5'--methoxyphosphorothioyl-2'-deoxyguanosine (G-P(O)═S)). ESR investigations show that DMTP(O)═S reacts with Cl to form the σσ* adduct radical -P-S[Formula: see text]Cl, which subsequently reacts with DMTP(O)═S to produce [-P-S[Formula: see text]S-P-].

The mechanism of organic radical oxidation catalysed by gold nanoparticles.

Metal nanoparticles can catalyze reactions involving organic free radicals. From the first studies focused on the catalytic reduction of water by free radicals until today, the catalytic oxidation of organic radicals has not received attention. In this work, we present the results on the catalytic activity of gold nanoparticles in the oxidation of 2-propanol to acetone and acetanilide hydroxylation during water radiolysis.

Dose Rate Effects in Fluorescence Chemical Dosimeters Exposed to Picosecond Electron Pulses: An Accurate Measurement of Low Doses at High Dose Rates.

The development of ultra-intense electron pulse for applications needs to be accompanied by the implementation of a practical dosimetry system. In this study four different systems were investigated as dosimeters for low doses with a very high-dose-rate source. First, the effects of ultra-short pulses were investigated for the yields of the Fricke dosimeter based on acidic solutions of ferrous sulfate; it was established that the yields were not significantly affected by the high dose rates, so the Fricke dosimeter system was used as a reference.

The mystery of sub-picosecond charge transfer following irradiation of hydrated uridine monophosphate.

The early mechanisms by which ionizing rays damage biological structures by so-called direct effects are largely elusive. In a recent picosecond pulse radiolysis study of concentrated uridine monophosphate solutions [J. Ma, S.

Quasi-Free Electron-Mediated Radiation Sensitization by C5-Halopyrimidines.

Substitution of the thymidine moiety in DNA by C5-substituted halogenated thymidine analogues causes significant augmentation of radiation damage in living cells. However, the molecular pathway involved in such radiosensitization process has not been clearly elucidated to date in solution at room temperature. So far, low-energy electrons (LEEs; 0-20 eV) under vacuum condition and solvated electrons (e) in solution are shown to produce the σ-type C5-centered pyrimidine base radical through dissociative electron attachment involving carbon-halogen bond breakage.

Radiolytic Approach for Efficient, Selective and Catalyst-free CO Conversion at Room Temperature.

The present study proposes a new approach for direct CO conversion using primary radicals from water irradiation. In order to ensure reduction of CO into CO by all the primary radiation-induced water radicals, we use formate ions to scavenge simultaneously the parent oxidizing radicals H and OH producing the same transient CO radicals. Conditions are optimized to obtain the highest conversion yield of CO .

Selective Oxidation of Transient Organic Radicals in the Presence of Gold Nanoparticles.

The ability of gold nanoparticles (AuNPs) to catalyze reactions involving radicals is poorly studied. However, AuNPs are used in applications where chemical reactions involving transient radicals occur. Herein, we investigate AuNPs' catalytic effect on 2-propanol oxidation and acetanilide hydroxylation in aqueous solutions under ionizing radiation at room temperature.

Reaction Mechanisms of the Degradation of Fluoroethylene Carbonate, an Additive of Lithium-Ion Batteries, Unraveled by Radiation Chemistry.

Numerous additives are used in the electrolytes of lithium-ion batteries, especially for the formation of an efficient solid electrolyte interphase at the surface of the electrodes. Understanding the degradation processes of these compounds is thus important; they can be seen through radiolysis. In the case of fluoroethylene carbonate (FEC), picosecond pulse radiolysis experiments evidenced the formation of FEC .