Revealing the steric effects of cobalt porphyrin on the selectivity of oxygen reduction reaction

It is well known that auxiliary groups have an important effect on the selectivity of Co porphyrins for oxygen reduction reaction (ORR). In this paper, the catalytic performance of picket fence cobalt porphyrin and its atropisomer for ORR are investigated by density functional theory methods. According to the structural characteristics, they are named alpha alpha alpha alpha and alpha beta alpha beta, respectively, and three catalytic sites are considered for them. The *O-2 is adequately activated on all studied sites, which is favorable for the further progress of ORR. For alpha alpha alpha alpha-I and alpha alpha alpha alpha-II, *OOH is more easily hydrogenated to form *O + H2O. That is, they have better selectivity for 4e(-) ORR. In contrast, alpha beta alpha beta tends to catalyze ORR through the 2e(-) pathway.

Automated summary

In this paper, the catalytic performance of picket fence cobalt porphyrin and its atropisomer for oxygen reduction reaction (ORR) are investigated by density functional theory methods. According to the structural characteristics, they are named alpha alpha alpha alpha and alpha beta alpha beta, respectively, and three catalytic sites are considered for them. The *O-2 is adequately activated on all studied sites, which is favorable for the further progress of ORR. For alpha alpha alpha alpha-I and alpha alpha alpha alpha-II, *OOH is more easily hydrogenated to form *O + H2O, showing better selectivity for 4e(-) ORR. In contrast, alpha beta alpha beta tends to catalyze ORR through the 2e(-) pathway.