Quantum chemistry of the oxygen reduction reaction (ORR) on Fe-G iron doped graphene for fuel cells

In this work, we used a dissociative mechanism to perform calculations based on Density Functional Theory, DFT, and electronic structure in order to study the oxygen reduction reaction on graphene doped with iron. The model takes into account some of the operating conditions of a proton exchange membrane fuel cell such as the equilibrium of hydrogen oxidation reaction, electrode potential of 1.23 V and 0 V, solvation effects, and corrections to the energy at the zero point (ZPE) and the entropic one. However, in this approach, we neglect the effects on the free energy of the interaction of the adsorbed species with the electric field due to the double electrochemical layer, the pH of the acid medium, and the oxygen coverage. The free energy diagrams for different intermediate steps of the oxygen reduction reaction, ORR, the oxygen adsorption energy on sites close to those occupied by the Fe-atoms, as well as the activity calculations indicated that Fe-Graphene (Fe-G) system, may possess catalytic properties close to either Pt, as catalyst, as its alloys since they can favor the ORR in a fuel cell proton exchange membrane. The results have been compared with other theoretical studies which use graphene as a central element as will be established in the present manuscript. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.