Nitrogen-Doped Fullerene as a Potential Catalyst for Hydrogen Fuel Cells

We examine the possibility of nitrogen-doped C-60 fullerene (N-C-60) as a cathode catalyst for hydrogen fuel cells. We use first-principles spin-polarized density functional theory calculations to simulate the electrocatalytic reactions on N-C-60. The first-principles results show that an O-2 molecule can be adsorbed and partially reduced on the N-C complex sites (Pauling sites) of N-C-60 without any activation barrier. Through a direct pathway, the partially reduced O-2 can further react with H+ and additional electrons and complete the water formation reaction (WFR) with no activation energy barrier. In the indirect pathway, reduced O-2 reacts with H+ and additional electrons to form H2O molecules through a transition state (TS) with a small activation barrier (0.22-0.37 eV). From an intermediate state to a TS, H+ can obtain a kinetic energy of similar to 0.95-3.68 eV, due to the Coulomb electric interaction, and easily overcome the activation energy barrier during the WFR. The full catalytic reaction cycles can be completed energetically, and N-C-60 fullerene recovers to its original structure for the next catalytic reaction cycle. N-C-60 fullerene is a potential cathode catalyst for hydrogen fuel cells.