Density Functional Theory Study on the Catalytic Behavior of OH
Functionalized N-Doped Graphene for Oxygen Reduction Reaction in Fuel
Cells
Abstract
Catalytic behavior of metal-free Hydroxyl group (OH) functionalized
single nitrogen (N-Gra(OH)16), and triple nitrogen (N3-Gra(OH)16) doped
graphene surface are investigated in the 4e- reduction pathway under
oxygen reduction reaction (ORR) process. The thermodynamical parameters
indicate the reaction to be highly exothermic and feasible with the
N-Gra(OH)16 and N3-Gra(OH)16 as catalysts. However, N3-Gra(OH)16 shows
better catalytic properties than N-Gra(OH)16. First, all reactive
species (*O2, *OOH, *O, and *OH) chemisorb via a covalent bond on the
N3-Gra(OH)16, which is essential for the efficient reaction kinetics.
Secondly, the product H2O is physisorbed on the N3-Gra(OH)16, required
for the uninterrupted reaction cycle. Categorically, the N3-Gra(OH)16
shows excellent catalytic activity due to a higher number of nitrogen
atoms which has a lowered EHOMO-LUMO gap, concomitantly increasing the
surface’s reactivity. Besides the above, the barrier energies are
comparable with platinum (Pt) catalyst. Our results show that the
N3-Gra(OH)16 surface is the most suitable catalyst for ORR activity.