title: Critical role of intercalated water for electrocatalytically active nitrogen-doped graphitic systems.
abstract: Graphitic materials are essential in energy conversion and storage because of their excellent chemical and electrical properties. The strategy for obtaining functional graphitic materials involves graphite oxidation and subsequent dissolution in aqueous media, forming graphene-oxide nanosheets (GNs). Restacked GNs contain substantial intercalated water that can react with heteroatom dopants or the graphene lattice during reduction. We demonstrate that removal of intercalated water using simple solvent treatments causes significant structural reorganization, substantially affecting the oxygen reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Amid contrasting reports describing the ORR activity of GN-based catalysts in alkaline electrolytes, we demonstrate superior activity in an acidic electrolyte with an onset potential of ~0.9 V, a half-wave potential (E ½) of 0.71 V, and a selectivity for four-electron reduction of >95%. Further, durability testing showed E ½ retention >95% in N2- and O2-saturated solutions after 2000 cycles, demonstrating the highest ORR activity and stability reported to date for GN-based electrocatalysts in acidic media.
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Ulises
authors.initials: U
authors.lastname: Martinez
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.; Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Dumont
authors.affiliation: Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Edward F
authors.identifier: 0000-0001-8419-6298
authors.initials: EF
authors.lastname: Holby
authors.affiliation: Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Kateryna
authors.identifier: 0000-0002-2611-0422
authors.initials: K
authors.lastname: Artyushkova
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Geraldine M
authors.initials: GM
authors.lastname: Purdy
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Akhilesh
authors.initials: A
authors.lastname: Singh
authors.affiliation: Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Nathan H
authors.initials: NH
authors.lastname: Mack
authors.affiliation: Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Plamen
authors.initials: P
authors.lastname: Atanassov
authors.affiliation: Materials Science and Technology Division, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Cullen
authors.affiliation: Materials Science and Technology Division, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Karren L
authors.initials: KL
authors.lastname: More
authors.affiliation: Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, NJ 08854, USA.
authors.forename: Manish
authors.initials: M
authors.lastname: Chhowalla
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Piotr
authors.initials: P
authors.lastname: Zelenay
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Dattelbaum
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Aditya D
authors.initials: AD
authors.lastname: Mohite
authors.affiliation: Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Gautam
authors.initials: G
authors.lastname: Gupta
mesh_terms: D002384:Catalysis; D004563:Electrochemistry; D006108:Graphite / Q000737:chemistry*; D008962:Models, Theoretical; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D010087:Oxides; D012997:Solvents; D014867:Water; D006108:Graphite; D009584:Nitrogen; D010100:Oxygen
keywords: Electrocatalysts; graphene oxide; intercalated water; oxygen reduction