title: Nitrogen-Doped Carbon Nanotube Arrays for High-Efficiency Electrochemical Reduction of CO2: On the Understanding of Defects, Defect Density, and Selectivity.
abstract: Nitrogen-doped carbon nanotubes (NCNTs) have been considered as a promising electrocatalyst for carbon-dioxide-reduction reactions, but two fundamental chemistry questions remain obscure: 1) What are the active centers with respect to various defect species and 2) what is the role of defect density on the selectivity of NCNTs? The aim of this work is to address these questions. The catalytic activity of NCNTs depends on the structural nature of nitrogen in CNTs and defect density. Comparing with pristine CNTs, the presence of graphitic and pyridinic nitrogen significantly decreases the overpotential (ca. -0.18 V) and increases the selectivity (ca. 80%) towards the formation of CO. The experimental results are in congruent with DFT calculations, which show that pyridinic defects retain a lone pair of electrons that are capable of binding CO2. However, for graphitic-like nitrogen, electrons are located in the π* antibonding orbital, making them less accessible for CO2 binding.
authors.affiliation: Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (USA).
authors.forename: Pranav P
authors.initials: PP
authors.lastname: Sharma
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University Houston, TX 77005 (USA).
authors.forename: Jingjie
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University Houston, TX 77005 (USA).
authors.forename: Ram Manohar
authors.initials: RM
authors.lastname: Yadav
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University Houston, TX 77005 (USA).
authors.forename: Mingjie
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (USA).
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Wright
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University Houston, TX 77005 (USA).
authors.forename: Chandra Sekhar
authors.initials: CS
authors.lastname: Tiwary
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University Houston, TX 77005 (USA).
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University Houston, TX 77005 (USA). jlou@rice.edu.
authors.forename: Jun
authors.initials: J
authors.lastname: Lou
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University Houston, TX 77005 (USA). ajayan@rice.edu.
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
authors.affiliation: Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (USA). zhox@cec.sc.edu.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Zhou
keywords: carbon dioxide fixation; carbon monoxide selectivity; carbon nanotubes; electrochemistry; nitrogen defects