title: Oxidative unzipping of stacked nitrogen-doped carbon nanotube cups.
abstract: We demonstrate a facile synthesis of different nanostructures by oxidative unzipping of stacked nitrogen-doped carbon nanotube cups (NCNCs). Depending on the initial number of stacked-cup segments, this method can yield graphene nanosheets (GNSs) or hybrid nanostructures comprised of graphene nanoribbons partially unzipped from a central nanotube core. Due to the stacked-cup structure of as-synthesized NCNCs, preventing complete exposure of graphitic planes, the unzipping mechanism is hindered, resulting in incomplete unzipping; however, individual, separated NCNCs are completely unzipped, yielding individual nitrogen-doped GNSs. Graphene-based materials have been employed as electrocatalysts for many important chemical reactions, and it has been proposed that increasing the reactive edges results in more efficient electrocatalysis. In this paper, we apply these graphene conjugates as electrocatalysts for the oxygen reduction reaction (ORR) to determine how the increase in reactive edges affects the electrocatalytic activity. This investigation introduces a new method for the improvement of ORR electrocatalysts by using nitrogen dopants more effectively, allowing for enhanced ORR performance with lower overall nitrogen content. Additionally, the GNSs were functionalized with gold nanoparticles (GNPs), resulting in a GNS/GNP hybrid, which shows efficient surface-enhanced Raman scattering and expands the scope of its application in advanced device fabrication and biosensing.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Dong
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Seth C
authors.initials: SC
authors.lastname: Burkert
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Alexander
authors.initials: A
authors.lastname: Star
mesh_terms: D003460:Crystallization / Q000379:methods; D006108:Graphite / Q000737:chemistry*; D008422:Materials Testing; D058726:Nanoconjugates / Q000737:chemistry* / Q000648:ultrastructure*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size
chemical_list: D058726:Nanoconjugates; D037742:Nanotubes, Carbon; D006108:Graphite; D009584:Nitrogen
keywords: carbon nanotubes; graphene−carbon nanotube hybrid structure; nitrogen doped; optimized morphology; unzipping