A DFT Study of the Oxygen Reduction Reaction Mechanism on Be Doped Graphene

Abstract Graphene despite its high surface area has very limited activity towards the oxygen reduction reaction (ORR), demonstrating selectivity towards the unfavorable two-electron mechanism. We have employed the spin polarized density functional theory (DFT) method to investigate the effect of the heteroatom p-type beryllium (Be) dopant on the oxygen reduction reaction activity of graphene. The preferred doping sites, active sites and reaction mechanism available on the doped graphene surfaces were investigated with increasing Be concentrations of 0.03 ML, 0.06 ML and 0.09 ML. Our results reveal that oxygen does not bind strongly to bare graphene, and Be at the lattice sites provides site for the oxygen adsorption and ORR. Oxygen binds dissociatively on the doped surfaces preferentially in the order 0.06 ML > 0.09 ML > 0.03 ML. From this studies introduction of Be impurities in a single honeycomb ring of graphene has significant impact on the binding and adsorbate-adsorbent interactions which leads to dissociative adsorption of oxygen, favouring the 4e- ORR pathway. The reaction is kinetically favoured most on the surface with a stronger O* binding and weaker OH* binding. Overall, the 0.03 ML and 0.06 ML doped surfaces are the most active facets for the ORR showing exergonic reaction energies at 0 V.