Reactions between HOCO+ and H2 Produce Water: A Computational Study

Controversies and arguments about the origin of planetary water have aroused enthusiasm to search for possible chemical sources. Considering the CO2-rich atmospheres of Mars, Venus, and the prebiotic Earth, here we propose that chemical reactions between HOCO+ and H2 can contribute to the production of H2O on the basis of high-level calculations. As for the reagents, HOCO+ could be formed by the protonation of CO2, while H+ and H2 are from the solar wind or interstellar space. Note that one of the reaction pathways undergoes multiple transition-state complexes and exhibits the roaming-like dynamics feature. Moreover, intermolecular proton or hydrogen transfer is a key step in the production of H2O, thereby H-tunneling effect profoundly enhances the reaction rate in a wide range of temperatures or collision energies.