title: Simultaneous Graphite Exfoliation and N Doping in Supercritical Ammonia.
abstract: We report the exfoliation of graphite and simultaneous N doping of graphene by two methods: supercritical ammonia treatment and liquid-phase exfoliation with NH4OH. While the supercritical ammonia allowed N doping at a level of 6.4 atom % in 2 h, the liquid-phase exfoliation with NH4OH allowed N doping at a level of 2.7 atom % in 6 h. The N doped graphene obtained via the supercritical ammonia route had few layers (<5) and showed large lateral flake size (∼8 μm) and low defect density (ID/IG< 0.6) in spite of their high level of N doping. This work is the first demonstration of supercritical ammonia as an exfoliation agent and N doping precursor for graphene. Notably, the N doped graphene showed electrocatalytic activity toward oxygen reduction reaction with high durability and good methanol tolerance compared to those of commercial Pt/C catalyst.
authors.forename: Suchithra Padmajan
authors.initials: SP
authors.lastname: Sasikala
authors.forename: Kai
authors.initials: K
authors.lastname: Huang
authors.forename: Baptiste
authors.initials: B
authors.lastname: Giroire
authors.affiliation: Department of Advanced Materials, Hannam University , Daejeon 305-811, South Korea.
authors.forename: Prem
authors.initials: P
authors.lastname: Prabhakaran
authors.forename: Lucile
authors.initials: L
authors.lastname: Henry
authors.forename: Alain
authors.initials: A
authors.lastname: Penicaud
authors.forename: Philippe
authors.initials: P
authors.lastname: Poulin
authors.forename: Cyril
authors.initials: C
authors.lastname: Aymonier
keywords: electrochemical catalyst; in situ N doping of graphene; liquid-phase exfoliation; oxygen reduction reaction; supercritical ammonia