Density Functional Theory Study on the Interaction of O_2 and H_2O_2 Molecules with the Active Sites of Cobalt-Polypyrrole Catalyst

摘要

We investigate the interaction of O_2 and H_2O_2 molecules with the active sites of cobalt-polypyrrole (Co-Ppy) catalyst using the density functional theory (DFT) calculations. Several configurations of Co-N_x clusters (x = 2, 3) are used to mimic the active sites structures of pyrolized Co-Ppy catalyst. The highest O-O bond elongation of the adsorbed O_2 molecule on Co-N_x clusters is of about 17.14%. The O_2 side-on adsorption configuration could be realized in the Co-N_2 active sites that have bent N-Co-N angles and strong d_(xz/yz)-orbitals characters in their frontier molecular orbitals (FMOs) and in the Co-N_3-pyridinic-trimer active site that has no occupied dz_2-like-orbital in its FMOs. Depending on the configuration of O_2 adsorption on Co-N_x clusters and the amount of extra charges in anti-bonding orbitals (π~*) of the adsorbed O_2 molecule, the formed H_2O_2 molecule on Co-N_x clusters will be spontaneously dissociated into OH~* molecules; otherwise it will be adsorbed in its molecular form.