Abiotic CO₂ reduction promoted by carbonate and phyllosilicate minerals on the primitive seafloor.

Abstract

Geoelectrochemical reduction of CO₂ is proposed as a potentially significant abiotic synthesis pathway catalyzed by sulfide minerals under planetary conditions, but whether this reaction could be catalyzed by geologically abundant carbonate and phyllosilicate minerals is unknown. Here we show that adsorption of trace transition metal cations, such as Cu(II) and Zn(II), endows common Ca/Mg-carbonates and phyllosilicates with high catalytic performance for CO₂ reduction to form methane, formic acid, carbon monoxide, and C₂ organics. We also observe viable synthesis of C-N bonded compounds (mainly acetamide) when ammonia is present. During these reactions, the adsorbed metal cations are partially reduced into metallic states and become catalytic, while mineral substrates facilitate the water dissociation to supply protons for CO₂ hydrogenation. This facile electrochemical reduction of CO₂ catalyzed by carbonates and phyllosilicates could facilitate the origin of life on the primitive Earth and help explain the detection of organics on other habitable planetary bodies.