Hydrogen production from low-temperature water-driven oxidation of iron

Understanding how hydrogen forms through mineral-water reactions is essential for studying Earth's earliest geochemistry and for developing clean energy sources. We experimentally demonstrate that water oxidizes ferrous ions in silica-rich alkaline solutions, producing substantial amounts of molecular hydrogen over a prolonged period of time. We propose a mechanism involving direct precipitation of green rust without any intermediate. This occurs when ferrous and chloride ions are compartmentalized within green-rust/silica double membranes, with continuous water reduction and iron oxidation driving hydrogen generation. At a planetary scale, this pathway may have been as important as serpentinization in providing H 2 essential for prebiotic reaction networks. Furthermore, the reaction we discovered could pave the way for a cost-effective method of producing molecular hydrogen.