Research ArticleGEOCHEMISTRY

Photoreduction of inorganic carbon(+IV) by elemental sulfur: Implications for prebiotic synthesis in terrestrial hot springs

See allHide authors and affiliations

Science Advances  18 Nov 2020:
Vol. 6, no. 47, eabc3687
DOI: 10.1126/sciadv.abc3687


Terrestrial hydrothermal systems have been proposed as alternative birthplaces for early life but lacked reasonable scenarios for the supply of biomolecules. Here, we show that elemental sulfur (S0), as the dominant mineral in terrestrial hot springs, can reduce carbon dioxide (CO2) into formic acid (HCOOH) under ultraviolet (UV) light below 280 nm. The semiconducting S0 is indicated to have a direct bandgap of 4.4 eV. The UV-excited S0 produces photoelectrons with a highly negative potential of −2.34 V (versus NHE, pH 7), which could reduce CO2 after accepting electrons from electron donors such as reducing sulfur species. Simultaneously, UV light breaks sulfur bonds, benefiting the adsorption of charged carbonates onto S0 and assisting their photoreduction. Assuming that terrestrial hot springs covered 1% of primitive Earth’s surface, S0 at 10 μM could have produced maximal 109 kg/year HCOOH within 10-cm-thick photic zones, underlying its remarkable contributions to the accumulation of prebiotic biomolecules.

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

View Full Text

Stay Connected to Science Advances