Experimental simulation of the formation processes of natural metal hydrides in sedimentary basins

• Discovery of temperature and pressure dependent hydrogenation in sedimentary basin conditions. • Experimental confirmation of metal hydride formation and stability. • Implications for natural hydrogen exploration and energy applications. Metal hydrides are essential materials with broad scientific and technological significance, showing unique properties in the fields of energy storage, catalysis, and superconductivity. Inspired by material science, we propose that natural hydrides can form in the Earth’s sedimentary basins due to existing favorable basis of matter and energy, which may provide a new perspective on understanding the geological origin and storage of natural hydrogen. In this study, we use a high-pressure gas reaction analyzer system to explore the hydrogenation reaction of typical transition metal powders (i.e., titanium (Ti), vanadium (V), chromium (Cr), and manganese (Mn)) under 50–200 ℃ and 3–5 MPa conditions relevant to sedimentary basins, and find that the hydrogenation reaction processes show apparent temperature dependence and can be efficiently promoted by pressure. Titanium exhibits a strong affinity for hydrogen, and its reaction with hydrogen is the largest among the four metals. The affinity of vanadium is second only to titanium. The affinity of chromium and manganese is at a similarly low level. As the temperature rises, the reaction quantity of titanium with hydrogen continues to increase; in contrast, the reaction quantity of vanadium and manganese with hydrogen shows a trend of first decreasing and then increasing; at 3 MPa, the reaction quantity of chromium with hydrogen shows a trend of first decreasing and then increasing, and at 5 MPa, the reaction quantity of chromium with hydrogen shows a trend of first increasing and then decreasing. After the in-situ hydrogenation experiments, combined XRD, ToF-SIMS, and NMR analysis on the quenched samples confirm the formation and stability of metal hydrides. Our study not only reveals the possibility of forming metal hydrides in sedimentary basins but also deepens our understanding of the metal-hydrogen interaction mechanism, providing a specific research basis for the formation of hydrides in shallow basins, which sheds light on the search for natural hydrides in sedimentary basins as a new energy source in the future.