Abstract: All 3d-transition-metal carbides (3d-TMCs) in the NaCl structure have been constructed to compare the catalytic activity of Li-O2 battery by first-principle calculations. The interfacial catalytic models of LixO2 (x=4, 2 and 1) molecules adsorbed on 3d-TMCs surfaces were used to simulate discharging (ORR, oxygen reduction reaction) and charging (OER, oxygen evolution reaction) processes. The calculated results indicate that TiC surface has smaller ORR and OER overpotentials, which may be the maximum catalytic activity of 3d-TMCs. Taking overpotentials as measurement of catalytic activity, some intrinsic properties related to catalytic activity are determined, including adsorption energies of Li and LiO2, surface energy and binding energy of O. The catalytic activities of 3d-TMCs for ORR and OER are inversely proportional to the adsorption energies of Li and LiO2. The ORR overpotentials are proportional to the surface energies of 3d-TMCs surfaces, but the relationship between OER overpotentials with the surface energies is not clear. TiC has a moderate binding energy of O atom. Additionally, when bonding state tends to be saturated, namely Fermi level happens to be in pseudogap, the catalytic activity reaches its maximum. 

https://doi.org/10.1021/acs.jpcc.8b04285