Durable Oxidation-Resistance of Copper via Light-Powered Bidentate Binding of Carbon Dioxide Anion Radicals

Environ. Sci. Technol. Lett.

Adjei

Denisov

et al. 2022

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The role of the short-lived hydrated electron (e aq − ) has recently begun to be appreciated in per-and polyfluoroalkyl substances (PFAS) remediations; nevertheless, few studies to date focused on short-chain PFAS, and their effective defluorination has been limited by an insufficient mechanistic understanding, which starts with the elusive initial step of e aq − reduction. Herein, this study uses pulse radiolysis to clarify the rate constant of the e aq − reaction with a highly recalcitrant short-chain PFAS, perfluorobutanesulfonate (PFBS, C 4 F 9 SO 3 − ), and verify chain length dependence. The measured values contradict earlier results from laser photolysis but reconcile with the apparent degradation profiles and theoretical predictions. Besides, we first disclose radiolytic carbon dioxide radicals (CO 2 −• ) to defluorinate PFBS with an initial reaction constant of 4.8 × 10 7 M −1 s −1 , and it achieves selective cleavage on the more obstinate C−F bond than e aq − even under a neutral condition. Quantitative 60 Co γ-ray irradiation experiments further show that initial reduction occurs through a defluorination pathway rather than a desulfurization pathway, and the redox potential of PFBS exceeds −2.0 eV. This radiolytic study addressed the long-standing mechanistic contradictions regarding short-chain PFAS degradation and suggested ionizing radiation as a versatile and direct treatment technique.

Section: Resultsmentioning

confidence: 99%

Transient Kinetics of Short-Chain Perfluoroalkyl Sulfonate with Radiolytic Reducing Species

Environ. Sci. Technol. Lett.

Adjei

Denisov

et al. 2022

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“…5a ); therefore, efficient CH 3 OH production requires a full understanding of the activation step and CO 2 •‒ binding motifs on a single-atom basis. Although some theoretical prediction and experimental evidence of surfaces bounded CO 2 •‒ were given 50 , 51 , most spectroscopic methods are inadequate to resolve the kinetics occurring on the timescale from nanoseconds to microseconds. To alleviate this shortcoming, we use pulse radiolysis to measure the CO 2 •‒ dynamics as a function of active metal sites and UiO-66(Hf) support.…”

Section: Resultsmentioning

confidence: 99%

Selective CO2 reduction to CH3OH over atomic dual-metal sites embedded in a metal-organic framework with high-energy radiation

et al. 2023

Nat Commun

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The efficient use of renewable X/γ-rays or accelerated electrons for chemical transformation of CO2 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 CH3OH production (~98%) over multiple irradiated cycles. The usage of practical electron-beam irradiation (200 keV; 40 kGy min−1) with a cost-effective hydroxyl radical scavenger promotes CH3OH production rate to 0.27 mmol g−1 min−1. Moreover, time-resolved experiments with calculations reveal the direct generation of CO2•‒ radical anions via aqueous electrons attachment occurred on nanosecond timescale, and cascade hydrogenation steps. Our study highlights a radiolytic route to produce CH3OH with CO2 feedstock and introduces a desirable atomic structure to improve performance.

“…•binding motifs on a single-atom basis. Although some theoretical prediction and experimental evidence of surfaces bounded CO 2 •were given 43,44 , most spectroscopic methods are inadequate to resolve the kinetics occurring on the timescale from nanoseconds to microseconds. To alleviate this shortcoming, we use pulse radiolysis to measure the CO 2 •dynamics as a function of active metal sites and UiO-66(Hf) support.…”

Section: Transient Kinetics By Pulse Radiolysismentioning

confidence: 99%

Sustainable high-energy radiation powering selective CO2 reduction to CH3OH over atomic dual-metal-sites embedded metal-organic framework

Wu³

et al. 2023

Preprint

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The efficient use of renewable high-energy radiation (X/γ-rays or accelerated e‒) as the energy input for the chemical transformation of carbon dioxide (CO2) and water to energy-rich fuels holds new promise for a carbon-neutral, sustainable energy economy; however, such processes are challenging to implement, and require the assistance of catalysts capable of sensitizing the secondary electron scattering and providing active metal sites to bind intermediates. Herein, we report that atomic Cu-Ni dual-metal-sites embedded in a metal-organic framework matrix enable efficient and selective (~ 98%) conversion of CO2 to CH3OH in irradiated aqueous solutions. The reaction is initiated by the direct generation of CO2•‒ radicals via aqueous electrons attachment, followed by a series of interfacial reactions. We showed that the UiO-66(Hf) matrix serves as a radiation sensitizer to break electron yield limitation in water radiolysis, dramatically promoting CO2 activation and conversion efficiency. With the synergistic metal centers and a hydroxyl radical scavenger, we achieved stable and selective CH3OH production over multiple irradiation cycles. Pulse radiolysis experiments with theoretical calculations revealed the transient kinetics occurred on the nanosecond timescale and cascade hydrogenation steps. Our study highlighted an unprecedented catalytic route to produce CH3OH with CO2 feedstock and introduced a desirable atomic structure to improve performance.