We investigate O(2) interaction with various metalloporphyrins (MnP, FeP, CoP, and NiP) using ab initio calculations based on density-functional theory. We discuss the trends in the activation barriers for the O-O bond cleavage in relation to the geometric, vibrational, electronic, and energetic properties of the systems. Whether the lowest unoccupied molecular orbital-highest occupied molecular orbital (LUMO-HOMO) levels of the metalloporphyrins involve the corresponding metal centers depends on the d orbital occupancies of the metals. We found that activation barriers for the O(2) dissociation can be mainly determined from the LUMO-HOMO characters of the metalloporphyrins, and consequently the FeP is the best catalyst with respect to the O(2) interaction from adsorption to dissociation.

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We investigate the electric and magnetic properties of a benzene–vanadium complex chain [V(C6H6)]∞. By performing first principles calculation based on the spin-polarized density functional theory, we find that this system shows a half metallic ferromagnetic behavior, i.e., majority-spin (spin-up) electrons have a semiconducting band gap, while minority-spin (spin-down) electrons are metallic. We suggest that this ferromagnetic order is due to a double-exchange mechanism.

In this work, we have investigated the conductivity, electrochemical window (ECW) and oxygen reduction reaction (ORR) in various bis(trifluoromethanesulfonyl)imide (TFSI)-based room temperature ionic liquids (RTILs). In an attempt to improve ORR activity in RTILs, water and/or dimethyl sulfoxide (DMSO) are added to one TFSI-based RTIL, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP-TFSI), and the effect of additives on its conductivity, ECW and ORR is explored. The results show that as-received TFSI-based ionic liquids (ILs) have a low conductivity due to their large constituent ions. The addition of water and/or DMSO has considerable effect on the conductivity of the IL mixture. The studied TFSI-based RTILs have wide ECWs and the presence of water and/or DMSO causes an apparent narrowing of the observed potential window. For all TFSI-based ILs, the oxygen redox peaks can be assigned to an O2/O2−• one-electron transfer process. By adding water, the O2/O2−• redox potential shifts in a more positive direction in BMP-TFSI; e.g., about 0.27 V more positive in BMP-TFSI with 1 wt% water addition, due to its high acceptor number (AN) and the proton effect. The addition of DMSO also contributes to the improvement in ORR activity in BMP-TFSI through enhanced conductivity and redox reversibility.