Fig. 3. Nonenzymatic reactions in the presence of as-prepared FeS (blue) and the FeS electrochemically reduced at −0.7 V (versus SHE) for 7 days (FeS_PERM) (red).

The yields were calculated relative to the initial amounts of starting materials of respective reactions. A full dataset for the identified and quantified products are presented in fig. S9 and tabulated in table S1 together with the results under the following conditions: with H₂ gas, with FeCl₂, with pure Fe⁰, and without reductant. The right diagram shows the reactions examined in the present study (a to g) and those demonstrated previously by simulating hydrothermal vent environments on the early Earth [CO₂ → CO in (6) and CO → C₂ and C₃ compounds in (7, 9)].