Density Functional Theory-Based Kinetic Modeling of Reactions of Hydrogen Isotopes (H2, D2, T2) and Carbonaceous Gases (CO2, CO, CH4) on the ZrCo(110) Surface

ZrCo and its alloys have attracted extensive attention as promising hydrogen isotope storage materials for nuclear fusion reactors. However, ZrCo can be readily poisoned by carbonaceous impurity gases like CO 2 and CO introduced by input hydrogen isotopes or produced during the fusion reactor operation procedure. In this work, with density functional theory calculations and microkinetic modeling, the poisoning effects of CO 2 and CO are identified by predominantly occupying active sites on the metal surface when reaching equilibrium. Surface reaction events related to CO 2 are mostly molecular adsorption–desorption steps due to its strong binding strength. Dissociation of CO occurs readily even at room temperature, and the resident time length for the coverage of hydrogen being higher than other species is longer than CO 2, indicating that the ZrCo alloy is more resistant to CO-poisoning compared to CO 2 . Interaction between CH 4 and ZrCo is not active with the coexistence of hydrogen, making this impurity inert in deteriorating hydrogen storage performance. Hydrogen isotope effects are characterized by comparing reactions among H 2 + CO 2 (CO), D 2 + CO 2 (CO), and T 2 + CO 2 (CO) mixing gases, with hydrogen resident time lengths decreasing from H 2 to T 2 .