We investigate O2 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 O2 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 O2 interaction from adsorption to dissociation.

Interactions of Fe–N ₄ and quaternary-N sites at the zigzag edge of graphene enhance the ORR free-energy profile of the quaternary-N site.

We study the adsorption of borohydride on Au and Au-based alloys (Au₃M with M = Cr, Mn, Fe, Co, and Ni) using first-principles calculations based on spin-polarized density functional theory. Favorable molecular adsorption and greater adsorption stability compared to pure Au are achieved on Au₃M alloys. For these alloys, there is an emergence of unoccupied states in the surface d band around the Fermi level with respect to the fully occupied d band of pure Au. Thus, the derived antibonding state of the sp–d interaction is upshifted and becomes unoccupied compared to pure Au. The B–H bond elongation of the adsorbed borohydride on these alloy surfaces points to the role of surface-parallel (d_xy and d_x²−y² states) components of the d-band of the alloying metal M, most pronouncedly in the cases of M = Co or Ni. On the alloy surfaces, B binds directly with the alloying metal, unlike in the case of pure Au where the surface bonding is through the H atoms. These results pose relevant insights into the design of Au-based anode catalysts for the direct borohydride fuel cell.