Engineering three-dimensional (3d) out-of-plane graphene edge sites for highly selective two-electron oxygen reduction electrocatalysis

Daniel San Roman, Dilip Krishnamurthy, Raghav Garg, Hasnain Hafiz, Michael Lamparski, Noel T. Nuhfer, Vincent Meunier, Venkatasubramanian Viswanathan, Tzahi Cohen-Karni

Research output: Contribution to journalArticlepeer-review

115 Scopus citations

Abstract

Selective two-electron oxygen reduction reaction (ORR) offers a promising route for hydrogen peroxide synthesis, and defective sp2-carbon-based materials are attractive, low-cost electrocatalysts for this process. However, due to a wide range of possible defect structures formed during material synthesis, the identification and fabrication of precise active sites remain a challenge. Here, we report a graphene edge-based electrocatalyst for two-electron ORR - nanowire-templated three-dimensional fuzzy graphene (NT-3DFG). NT-3DFG exhibits notable efficiency [onset potential of 0.79 ± 0.01 V vs reversible hydrogen electrode (RHE)], high selectivity (94 ± 2% H2O2), and tunable ORR activity as a function of graphene edge site density. Using spectroscopic surface characterization and density functional theory calculations, we find that NT-3DFG edge sites are readily functionalized by carbonyl (C═O) and hydroxyl (C-OH) groups under alkaline ORR conditions. Our calculations indicate that multiple functionalized configurations at both armchair and zigzag edges may achieve a local coordination environment that allows selective, two-electron ORR. We derive a generalized geometric descriptor based on the local coordination environment that provides activity predictions of graphene surface sites within ∼0.1 V of computed values. We combine synthesis, spectroscopy, and simulations to improve active site characterization and accelerate carbon-based electrocatalyst discovery.

Original languageEnglish (US)
Pages (from-to)1993-2008
Number of pages16
JournalACS Catalysis
Volume10
Issue number3
DOIs
StatePublished - Feb 7 2020

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry

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