“Metal-free” electrocatalysis: Quaternary-doped graphene and the alkaline oxygen reduction reaction

• Published in: Applied catalysis. A, General Vol. 553; pp. 107 - 116
• Main Authors: Molina-García, Miguel A., Rees, Neil V.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05-03-2018; Elsevier Science SA
• Subjects: Catalysis; Catalysts; Catalytic activity; Chemical synthesis; Doped-graphene; Electrocatalysis; Electron transfer; Fuel cells; Graphene; Metal-free catalyst; Methanol; Nitrogen; Oxygen; Oxygen reduction reaction; Oxygen reduction reactions; Phosphorus; Pyrolysis; Rotating-ring disk electrode; Metal-free catalyst; Doped-graphene; Rotating-ring disk electrode; Oxygen reduction reaction
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2017.12.014

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•A novel metal-free catalyst of graphene doped with B,N,P, and S is reported for the alkaline oxygen reduction reaction.•The quaternary-doped graphene is more catalytic than single-doped analogs, reducing peroxide formation from >40% to 15%.•Unlike Pt/C catalysts, the quaternary-doped graphene is immune to the presence of MeOH, so is a good candidate for DMFCs.
We report the first investigation into a quaternary-doped graphene catalyst material for the oxygen reduction reaction (ORR) under alkaline conditions. The material was synthesized via direct pyrolysis of graphene oxide (GO) with boron, nitrogen, phosphorus and sulfur precursors. The resulting BNPS-Gr catalyst was thoroughly characterized and its composition found via XPS to be 6.4% (B), 6.1% (N), 2.6% (P) and 0.5% (S), while HR-TEM imaging shows a few-layered graphene structure. Electrochemical investigations into the catalytic activity towards the ORR show improved performance of the quaternary-doped graphene with the effective number of electrons transferred being ca. 3.7, compared to single-doped graphenes (2.9–3.2) and significantly lower peroxide production. This demonstrates BNPS-Gr to be a promising alternative to current Pt-group catalysts for the ORR, especially in methanol-fuelled fuel cells, where the presence of methanol in the cathode side from the fuel crossover is shown not to affect the performance of the quaternary-doped graphene catalyst.