title: Engineering Favorable Morphology and Structure of Fe-N-C Oxygen-Reduction Catalysts through Tuning of Nitrogen/Carbon Precursors.
abstract: Structures and morphologies of Fe-N-C catalysts are believed to be crucial because of the number of active sites and local bonding structures governing the overall catalyst performance for the oxygen reduction reaction (ORR). However, the knowledge how to rationally design catalysts is still lacking. By combining different nitrogen/carbon precursors, including polyaniline (PANI), dicyandiamide (DCDA), and melamine (MLMN), we aim to tune catalyst morphology and structure to facilitate the ORR. Instead of the commonly studied single precursors, multiple precursors were used during the synthesis; this provides a new opportunity to promote catalyst activity and stability through a likely synergistic effect. The best-performing Fe-N-C catalyst derived from PANI+DCDA is superior to the individual PANI or DCDA-derived ones. In particular, when compared to the extensively explored PANI-derived catalysts, the binary precursors have an increased half-wave potential of 0.83 V and an enhanced electrochemical stability in challenging acidic media, indicating a significantly increased number of active sites and strengthened local bonding structures. Multiple key factors associated with the observed promotion are elucidated, including the optimal pore size distribution, highest electrochemically active surface area, presence of dominant amorphous carbon, and thick graphitic carbon layers with more pyridinic nitrogen edge sites likely bonded with active atomic iron.
authors.affiliation: Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.
authors.forename: Shiva
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Giner Inc., Newton, MA, 02466, USA.
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.
authors.forename: Ogechi
authors.initials: O
authors.lastname: Ogoke
authors.affiliation: Department of Chemical Engineering, University of South Carolina, Columbia, SC, 29208, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Giner Inc., Newton, MA, 02466, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.
authors.forename: Gang
authors.identifier: 0000-0003-4956-5208
authors.initials: G
authors.lastname: Wu
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D020134:Catalytic Domain; D004738:Engineering / Q000379:methods; D007501:Iron / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D016062:Porosity
chemical_list: D002244:Carbon; D007501:Iron; D009584:Nitrogen
keywords: electrocatalysis; nonprecious metals; oxygen reduction reaction; polyaniline; precursors