  Boron-doped graphene was reported to be the best non-metal doped graphene
electrocatalyst for the oxygen reduction reaction (ORR) working at an onset
potential of 0.035 V [JACS 136 (2014) 4394]. In the present DFT study,
intermediates and transition structures along the possible reaction pathways
are determined. Both Langmuir-Hinschelwood and Eley-Rideal mechanisms are
discussed. Molecular oxygen binds the positively charged B atom and forms an
open shell end-on dioxygen intermediate. The associative path is favoured with
respect to the dissociative one. The free energy diagrams along the
four-reduction steps are investigated with the methodology by N{\o}rskov and
co. [JPC B 108 (2004) 17886] in both acidic and alkaline conditions. The pH
effect on the stability of the intermediates of reduction is analyzed in terms
of the Pourbaix diagram. At pH = 14 we compute an onset potential value for the
electrochemical ORR of U = 0.05 V, which compares very well with the
experimental value in alkaline conditions.
