Hydrogen gas, H₂, is generated by alkaline hydrothermal vents through an ancient geochemical process called serpentinization, in which water reacts with iron-containing minerals deep within the Earth’s crust. H₂ is the electron donor for the most ancient and the only energy-releasing route of biological CO₂ fixation, the acetyl-CoA pathway. At the origin of metabolism, CO₂ fixation by hydrothermal H₂ within serpentinizing systems could have preceded and patterned biotic pathways. Here we show that three hydrothermal minerals—greigite (Fe₃S₄), magnetite (Fe₃O₄) and awaruite (Ni₃Fe)—catalyse the fixation of CO₂ with H₂ at 100 °C under alkaline aqueous conditions. The product spectrum includes formate (up to 200 mM), acetate (up to 100 µM), pyruvate (up to 10 µM), methanol (up to 100 µM) and methane. The results shed light on both the geochemical origin of microbial metabolism and the nature of abiotic formate and methane synthesis in modern hydrothermal vents.

氢气 H ₂是由碱性热液喷口通过称为蛇纹石化的古老地球化学过程产生的，在该过程中水与地壳深处的含铁矿物发生反应。H _{2是生物CO 2}固定的最古老和唯一的能量释放途径乙酰辅酶A途径的电子供体。在新陈代谢的起源，蛇纹石化系统中通过热液 H 2 固定_{CO 2}可能先于并形成生物途径。在这里，我们展示了三种热液矿物——灰辉石 (Fe ₃ S ₄ )、磁铁矿 (Fe ₃ O ₄ ) 和橄榄石 (Ni ₃Fe)——在碱性水溶液条件下，在 100 °C 下催化 CO ₂与 H _{2的固定。}产品光谱包括甲酸盐（最高 200 mM）、乙酸盐（最高 100 µM）、丙酮酸盐（最高 10 µM）、甲醇（最高 100 µM）和甲烷。结果揭示了现代热液喷口中微生物代谢的地球化学起源以及非生物甲酸盐和甲烷合成的性质。