Unlocking the possible role of rhodochrosite for the geo-electrosynthesis of ammonia and urea in early ocean

The emergence of bio-essential nitrogenous molecules like ammonia and urea on early Earth is crucial for the origins of life. Herein, we propose a prebiotic molecular synthesis process involving ammonia and urea on rhodochrosite via a geo-electrochemical mechanism, offering another similar inorganic pathway that produces simple molecules like methane and carbon monoxide in primordial environments. Though long overlooked, Mn element is an essential cofactor in redox enzymes and linked to organic-rich mineral deposits, indicating its role in early biological processes. In this context, the potential of rhodochrosite (the most abundant sedimentary manganese-bearing mineral with naturally doping) to catalyze the conversion of NOx⁻ and CO₂ into NH₃ and/or urea within a geo-electrochemical system was explore. In situ experiments and theoretical modeling show that dopant modulation of Mn sites optimizes the d-band center, strengthening adsorption of NOx⁻ and CO₂ and enabling efficient NH₃ and urea production. This finding provides an abiotic pathway for the accumulation of key nitrogenous compounds under prebiotic oceanic conditions, without enzymes or extreme processes, suggesting a compelling mineral-mediated origin for prebiotic nitrogenous molecules.