Radiolytic Approach for Efficient, Selective and Catalyst‐free CO₂ Conversion at Room Temperature

Abstract

The present study proposes a new approach for direct CO2 conversion using primary radicals from water irradiation. In order to ensure reduction of CO2 into CO2 -• by all the hydrated electrons, we use formate ions to scavenge simultaneously the parent oxidizing radicals H • and OH • producing the same transient CO2 -• radicals. Conditions are optimized to obtain the highest conversion yield of CO2. The goal is achieved under mild conditions of room temperature, neutral pH and 1 atm of CO2 pressure. All the available radicals are exploited for selectively converting CO2 into oxalate that is accompanied by H2 evolution. The mechanism presented accounts for the results and also sheds light on the data in the literature. The radiolytic approach is a mild and scalable route of direct CO2 capture at the source in industry and the products, oxalate salt and H2, can be easily separated.

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

“…Briefly, potassium heptadecafluoro-1-octanesulfonate (C 8 F 17 SO 3 K, PFOS) and potassium perfluorobutanesulfonate (C 4 F 9 SO 3 K, PFBS) were purchased from Sigma-Aldrich and were used as received. Pulse radiolysis experiments were carried out employing the picosecond laser-triggered electron accelerator, ELYSE, coupled with a time-resolved absorption spectrophotometric detection system (290–720 nm). − The steady-state experiments were conducted at a 60 Co gamma source (5.35 × 10 13 Bq, located in the Université Paris-Saclay) at a dose rate of 2.25 kGy/h at ambient conditions. The sample solutions were prepared in ultrapure water (18.2 MΩ cm), and the pH was adjusted by a NaOH solution.…”

“…It also represents a versatile approach to produce and real-time visualize other highly reducing species such as H • and CO 2 −• , which is rarely accessible by the existing techniques. 31,32 Here, we report that pulse radiolysis is used to find the rate constant for PFBS with e aq − , and the long-lasting gap between carbon chain length and defluorination efficacy has been filled using transient absorption combined with 60 Co gamma steady-state irradiation experiments. Furthermore, we found carbon dioxide radicals (CO 2 −• ) enabled selective cleavage on more the intractable C−F bond than e aq − and promises a complement for PFBS defluorination.…”

“…As opposed to laser photolysis, pulse radiolysis delivers a high-energy electron pulse to ionize water, so e aq – can be directly formed without the optical artifacts that are often associated with photochemical processes involving e aq – sensitizers such as K 4 Fe­(CN) 6 and sulfite. − Moreover, based on the specific radiolytic yield of species, the radiolytic method allows elucidating quantitatively the pathway and efficiency of defluorination. It also represents a versatile approach to produce and real-time visualize other highly reducing species such as H • and CO 2 –• , which is rarely accessible by the existing techniques. , Here, we report that pulse radiolysis is used to find the rate constant for PFBS with e aq – , and the long-lasting gap between carbon chain length and defluorination efficacy has been filled using transient absorption combined with 60 Co gamma steady-state irradiation experiments. Furthermore, we found carbon dioxide radicals (CO 2 –• ) enabled selective cleavage on more the intractable C–F bond than e aq – and promises a complement for PFBS defluorination.…”

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

“…•− radicals needed for the layer formation is estimated to be about 10 −4 mol L −1 based on the known yields of radiolytic precursor species ( • OH, • H, and e sol − ). 35 As the competing CO 2…”

“…From the quantitative radiolysis experiments at certain doses, the minimum concentration of CO 2 •– radicals needed for the layer formation is estimated to be about 10 –4 mol L –1 based on the known yields of radiolytic precursor species ( • OH, • H, and e sol – ) . As the competing CO 2 •– self-recombination reaction occurs rapidly (CO 2 •– + CO 2 •– → C 2 O 4 2– ; k 3 = 1.4 × 10 9 L mol –1 s –1 at 20 °C), the sufficient coverage on Cu suggested the effective CO 2 •– attachment.…”