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1. Cobalt-Group 13 Complexes Catalyze CO ₂ Hydrogenation via a Co(−I)/Co(I) Redox Cycle

   https://doi.org/10.1021/acscatal.9b03534  

   Vollmer, Matthew V.; Ye, Jingyun; Linehan, John C.; Graziano, Brendan J.; Preston, Andrew; Wiedner, Eric S.; Lu, Connie C. (January 2020, ACS Catalysis)
2. Heterogeneous Electrocatalysts for Metal–CO ₂ Batteries and CO ₂ Electrolysis

   https://doi.org/10.1021/acsenergylett.2c02445  

   Wang, Jianda; Marchetti, Barbara; Zhou, Xiao-Dong; Wei, Shuya (April 2023, ACS Energy Letters)
3. Formation of CO ₂ Hydrates within Single-Walled Carbon Nanotubes at Ambient Pressure: CO ₂ Capture and Selective Separation of a CO ₂ /H ₂ Mixture in Water

   https://doi.org/10.1021/acs.jpcc.7b12700  

   Zhao, Wenhui; Bai, Jaeil; Francisco, Joseph S.; Zeng, Xiao Cheng (April 2018, The Journal of Physical Chemistry C)
4. CO ₂ reduction driven by a pH gradient

   https://doi.org/10.1073/pnas.2002659117  

   Hudson, Reuben; de Graaf, Ruvan; Strandoo Rodin, Mari; Ohno, Aya; Lane, Nick; McGlynn, Shawn E.; Yamada, Yoichi M.; Nakamura, Ryuhei; Barge, Laura M.; Braun, Dieter; et al (September 2020, Proceedings of the National Academy of Sciences)

   null (Ed.)

   All life on Earth is built of organic molecules, so the primordial sources of reduced carbon remain a major open question in studies of the origin of life. A variant of the alkaline-hydrothermal-vent theory for life’s emergence suggests that organics could have been produced by the reduction of CO 2 via H 2 oxidation, facilitated by geologically sustained pH gradients. The process would be an abiotic analog—and proposed evolutionary predecessor—of the Wood–Ljungdahl acetyl-CoA pathway of modern archaea and bacteria. The first energetic bottleneck of the pathway involves the endergonic reduction of CO 2 with H 2 to formate (HCOO – ), which has proven elusive in mild abiotic settings. Here we show the reduction of CO 2 with H 2 at room temperature under moderate pressures (1.5 bar), driven by microfluidic pH gradients across inorganic Fe(Ni)S precipitates. Isotopic labeling with 13 C confirmed formate production. Separately, deuterium ( 2 H) labeling indicated that electron transfer to CO 2 does not occur via direct hydrogenation with H 2 but instead, freshly deposited Fe(Ni)S precipitates appear to facilitate electron transfer in an electrochemical-cell mechanism with two distinct half-reactions. Decreasing the pH gradient significantly, removing H 2 , or eliminating the precipitate yielded no detectable product. Our work demonstrates the feasibility of spatially separated yet electrically coupled geochemical reactions as drivers of otherwise endergonic processes. Beyond corroborating the ability of early-Earth alkaline hydrothermal systems to couple carbon reduction to hydrogen oxidation through biologically relevant mechanisms, these results may also be of significance for industrial and environmental applications, where other redox reactions could be facilitated using similarly mild approaches. 

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5. Toward a Cenozoic history of atmospheric CO ₂

   https://doi.org/10.1126/science.adi5177  

   Hönisch, Bärbel; Royer, Dana L.; Breecker, Daniel O.; Polissar, Pratigya J.; Bowen, Gabriel J.; Henehan, Michael J.; Cui, Ying; Steinthorsdottir, Margret; McElwain, Jennifer C.; Kohn, Matthew J.; et al (December 2023, Science)

   The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO₂) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO₂beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions, degree of understanding, and even reconstructed values. In this study, we critically evaluated, categorized, and integrated available proxies to create a high-fidelity and transparently constructed atmospheric CO₂record spanning the past 66 million years. This newly constructed record provides clearer evidence for higher Earth system sensitivity in the past and for the role of CO₂thresholds in biological and cryosphere evolution. 

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