B‐ and N‐Doped Carbon Electrocatalysts for Oxygen Reduction Reaction: Influence of Carbon Chemical Modification

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Abstract
The synthesis of metal‐free electrocatalysts for oxygen reduction reaction (ORR) in fuel cells has attracted remarkable attention. We report the synthesis of B, N, and BN co‐doped carbon materials by the hydrothermal method. The effect of surface oxygen on graphene oxide over the amount of N and B doping was investigated. Two types of carbon were evaluated: 1) commercial graphene oxide (GO comm ) and 2) GO chemically modified. GO exhibited higher surface oxygen (27.16%) and structural defects (I D /I G = 0.97) after chemical modification, which favors the amount of heteroatom doping. The N‐doped carbon (N‐GO and N‐GO comm ) showed a higher onset potential (E onset ) than B‐doped carbon samples (B‐GO and B‐GO comm ), which can be associated with the higher amount of N‐doping, N electronegativity, and N‐species obtained. The BN co‐doped GO showed a synergetic effect, increasing the limited and kinetic current density, and the number of electrons transferred closer to four ( n = 3.9 e‐). The presence of both N (pyridinic/quaternary) and B (BC 3 ) heteroatoms increased the activity of B‐N‐GO for the ORR, showing a higher current density in both kinetic and mass transfer regions. This work provides new alternatives of an attractive electrocatalyst (B‐N‐GO) for ORR application.

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