eprintid: 10084147 rev_number: 18 eprint_status: archive userid: 608 dir: disk0/10/08/41/47 datestamp: 2019-10-24 11:07:53 lastmod: 2021-09-19 23:52:16 status_changed: 2019-10-24 11:07:53 type: article metadata_visibility: show creators_name: Vasiliadou, R creators_name: Dimov, N creators_name: Szita, N creators_name: Jordan, SF creators_name: Lane, N title: Possible mechanisms of CO₂ reduction by H₂ via prebiotic vectorial electrochemistry ispublished: pub divisions: UCL divisions: B02 divisions: C08 divisions: D09 divisions: F99 divisions: B04 divisions: C05 divisions: F47 keywords: CO2 reduction, origin of life, vectorial chemistry, energy-converting hydrogenase, alkaline hydrothermal vents, microfluidic reactor note: Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. abstract: Methanogens are putatively ancestral autotrophs that reduce CO2 with H2 to form biomass using a membrane-bound, proton-motive Fe(Ni)S protein called the energy-converting hydrogenase (Ech). At the origin of life, geologically sustained H+ gradients across inorganic barriers containing Fe(Ni)S minerals could theoretically have driven CO2 reduction by H2 through vectorial chemistry in a similar way to Ech. pH modulation of the redox potentials of H2, CO2 and Fe(Ni)S minerals could in principle enable an otherwise endergonic reaction. Here, we analyse whether vectorial electrochemistry can facilitate the reduction of CO2 by H2 under alkaline hydrothermal conditions using a microfluidic reactor. We present pilot data showing that steep pH gradients of approximately 5 pH units can be sustained over greater than 5 h across Fe(Ni)S barriers, with H+-flux across the barrier about two million-fold faster than OH–-flux. This high flux produces a calculated 3-pH unit-gradient (equating to 180 mV) across single approximately 25-nm Fe(Ni)S nanocrystals, which is close to that required to reduce CO2. However, the poor solubility of H2 at atmospheric pressure limits CO2 reduction by H2, explaining why organic synthesis has so far proved elusive in our reactor. Higher H2 concentration will be needed in future to facilitate CO2 reduction through prebiotic vectorial electrochemistry. date: 2019-12 date_type: published publisher: The Royal Society official_url: https://doi.org/10.1098/rsfs.2019.0073 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1710073 doi: 10.1098/rsfs.2019.0073 lyricists_name: Jordan, Sean lyricists_name: Lane, Nicholas lyricists_name: Szita, Nicolas lyricists_id: SJORD72 lyricists_id: NJLAN31 lyricists_id: NSZIT68 actors_name: Kalinowski, Damian actors_id: DKALI47 actors_role: owner full_text_status: public publication: Interface Focus volume: 9 number: 6 issn: 2042-8901 citation: Vasiliadou, R; Dimov, N; Szita, N; Jordan, SF; Lane, N; (2019) Possible mechanisms of CO₂ reduction by H₂ via prebiotic vectorial electrochemistry. Interface Focus , 9 (6) 10.1098/rsfs.2019.0073 <https://doi.org/10.1098/rsfs.2019.0073>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10084147/1/Jordan_Possible%20mechanisms%20of%20CO%E2%82%82%20reduction%20by%20H%E2%82%82%20via%20prebiotic%20vectorial%20electrochemistry_VoR.pdf