First-Principles Calculation of H/CO2 Interaction in Plasma: A Density Functional Theory-Based Study

An in-depth understanding of the microscopic mechanism of the reaction of hydrogen isotopes with CO2 under irradiation conditions can provide data support for the optimal design of the deuterium-tritium fuel cycle process for fusion reactors. Based on this, the microscopic reaction mechanism of H-2 and CO2 under the condition of plasma discharge was studied by first-principles calculation, and the influences of different temperatures and hydrogen isotope effect on the reaction process were studied. The principal calculation was carried out by the Gaussian 09 software package. The enthalpies and activation energies of these reactions were measured at the level of M06-2X/6-311++G (3d2f, 3p2d). Four initial reaction paths are obtained by using the intrinsic reaction coordinate (IRC) algorithm and finding the transition state of the combined reaction. The thermodynamic easiness of the two pathways to produce CH4 and CH3OH and the influence of different hydrogen isotopes on each reaction were compared and studied. It is found that the spontaneous decay of tritium or the high-energy electrons in the plasma will induce hydrogen isotopes to react with CO2 to form products such as CO, H2O, CH4, and CH3OH; after the high-energy electrons induce the dissociation of CO2, there are four initial reaction paths. Complex reactions can occur on their own, and there are two tendencies to this complex reaction. Raising the reaction temperature has a certain promoting effect on the conversion of CO2 into organic matter (CH4 and CH3OH).