Abstract: First-principles calculations were performed to investigate the catalytic activity of Ti₂C MXene material as a potential cathode in Li–O₂ batteries. Stable non-, O-, F-, OH-terminated Ti₂C MXenes are constructed to show the real state of Ti₂C MXene monolayer in the experiment. Then, the interfacial models of LixO₂ (x = 4, 2, and 1) molecules adsorbed on Ti₂C, Ti₂CO₂, Ti₂CF₂, and Ti₂C(OH)₂ MXenes were used to simulate the structural evolution during discharging (oxygen reduction reaction, ORR) and charging (oxygen evolution reaction, OER) processes. The catalytic activity was quantitatively assessed by calculating the ORR and OER overpotentials. Among them, Ti₂CO₂ MXene displays the best catalytic activity with the lowest ORR/OER/TOT overpotential, suggesting that O-terminated Ti₂C MXene is more favorable for Li–O₂ batteries. This is because the Ti 3d orbital of the Ti₂CO₂ surface is completely polarized near the Fermi level, showing strong oxidation capability toward O22–. These findings give a theoretical guidance for Ti₂C MXene used in Li–O₂ batteries and widen the applications of MXene-based materials.

DOI: 10.1021/acs.jpcc.9b05698