Structural disorder-driven synthesis of C2+ hydrocarbons via direct hydrogenation of amorphous carbon with continuous random atomic networks

Recent advances in geoscience have underscored the critical role of abiogenic processes in petroleum formation, especially the formation and polymerization of methane. However, whether a direct carbon–H2 reaction can produce C2+ hydrocarbons (e.g., ethane and propane) beyond methane remains an open question. Here, we demonstrate the direct synthesis of ethane and propane via reactions between amorphous carbon and H2 under upper mantle conditions (2–10 GPa and 800–1200 °C). A systematic investigation reveals that increasing structural disorder in carbon precursors, from graphite to glassy carbon-II and carbon black, enhances the production of C2–C3 hydrocarbons. Through integrated X-ray diffraction and reverse Monte Carlo simulations, we establish that the continuous random atomic network structures in amorphous carbon enable one-step synthesis of heavy hydrocarbons with H2. These models establish a direct link between atomic-scale carbon structures and the one-step synthesis of C2+ hydrocarbons under H2-rich, high-pressure, and high-temperature conditions—potentially revealing an efficient mechanism for the abiotic production of C2+ hydrocarbons in the upper mantle.