Insight into the interfacial interactions of CO2 with PuH2 (100), (110), and (111) surfaces from first-principles calculations

The interface interaction behavior and mechanism between CO2 molecule and PuH2 (100), (110), and (111) surfaces were investigated by GGA + U method. It is found that both strong chemical adsorption and weak physical adsorption exist between CO2 and PuH2 surfaces. In all the adsorption configurations considered in this study, the adsorption energy results suggest that CO2 may have relatively strong reactivity with (110) surface. In the strongest adsorption, the C-O bonds can be extended from about 1.176 angstrom in gas phase to about 1.287 angstrom, and the bond angle bends from 180 degrees to 120.78 degrees. The CO2 adsorption configurations on the surfaces reveals that the adsorbed CO2 is captured by surface Pu atoms, and new Pu-O and Pu-C bonds are generated on the hydride surface. The surface work function could increase from about 2.007 eV of clean surface to about 3.239 eV of CO2/ slab system. The vibration frequencies and electronic properties indicate that the reduction of vibrational fre-quencies and the prolongation of C-O bonds of CO2 are attributed to the charge transfer between the CO2 and surface atoms during adsorption. The research can offer useful details for the adsorption morphology and interfacial reaction behavior of CO2 on hydride surface.