The Electrochemical Reduction of CO₂ to Formate in Hydrothermal Sulfide ore Deposit as a Novel Source of Organic Matter

Abstract

Earlier models for organic synthesis in the conditions of sulfide hydrotherms were based on the ability of sulfide minerals (chalcogenides) and hydrogen sulfide to act as electron donors inchemical reductionofwater-dissolved CO₂ to organic molecules (for literature sources see Vladimirov et al., 2004). The detailed analysis suggests a possibility of another mechanism: a direct electrochemical reduction of CO₂ at the surface of metal-sulfide minerals, for instance pyrite or galenite. When putting forward this hypothesis, we proceeded from the fact that electrode potentials of sulfide minerals can reach considerable magnitudes varying with composition and structureofmineral. Because chalcogenides are capableofconducting electrical current, the contact of mineral bodies of different structures must lead to arising of galvanic circuits with an electromotive force of about several volts. The functioning of such circuits has been registered under natural conditions.