Sulfide Mineral Reduces CO₂

An iron sulfide mineral that forms in deep sea hydrothermal vents can convert CO₂ and hydrogen to small bioorganic molecule precursors such as methanol and formic, acetic, and pyruvic acid (Chem. Commun. 2015, DOI: 10.1039/c5cc02078f). The discovery, by Nora H. de Leeuw of University College London and colleagues, provides a potential lead for developing environmentally friendly catalytic syntheses of plastics and fuels. It also lends credence to the theory that prebiotic chemistry flourished in the mineral- and carbon-rich alkaline environment that typifies some hydrothermal vents. Scientists have known that this mineral, greigite (Fe₃S₄), resembles the ferredoxin center of the CO dehydrogenase enzyme. In previous studies, researchers showed that greigite can convert CO₂ to gaseous CH₄ and CO. However, to serve as prebiotic precursors, small organics must be in solution. So the team performed experiments at various pH values and found that an alkaline environment was key to producing methanol and the other small organics that are solution-based at atmospheric pressure and room temperature. And by using computational methods, the group explained the dependence of the methanol and formic acid formation mechanisms on alkaline conditions.