TY - JOUR
T1 - Engineering three-dimensional (3d) out-of-plane graphene edge sites for highly selective two-electron oxygen reduction electrocatalysis
AU - San Roman, Daniel
AU - Krishnamurthy, Dilip
AU - Garg, Raghav
AU - Hafiz, Hasnain
AU - Lamparski, Michael
AU - Nuhfer, Noel T.
AU - Meunier, Vincent
AU - Viswanathan, Venkatasubramanian
AU - Cohen-Karni, Tzahi
N1 - Funding Information:
T.C.-K. gratefully acknowledges funding support from the National Science Foundation under Award No. CBET1552833 and the Office of Naval Research under Award No. N000141712368. D.K. and V.V. gratefully acknowledge funding support from the National Science Foundation under Award No. CBET1554273. H.H. acknowledges support from the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Fuel Cell Technologies Office (FCTO) under Award Number DE-EE0008076. D.S.R. acknowledges Dr. S. Lister and X. Xu for assistance with electrochemistry experiments and thanks D. Flaherty for assistance with experimental EELS measurements. D.K. acknowledges Dr. O. Sapunkov’s assistance with rendering the DFT-simulated structures. The authors also acknowledge support from the Carnegie Mellon University Nanofabrication Facility and Department of Materials Science and Engineering Materials Characterization Facility (MCF-677785).
Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/2/7
Y1 - 2020/2/7
N2 - 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.
AB - 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.
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U2 - 10.1021/acscatal.9b03919
DO - 10.1021/acscatal.9b03919
M3 - Article
AN - SCOPUS:85078920714
SN - 2155-5435
VL - 10
SP - 1993
EP - 2008
JO - ACS Catalysis
JF - ACS Catalysis
IS - 3
ER -