Abstract
Nitrogen-doped carbon is a promising metal- free catalyst for oxygen reduction reaction in fuel cells and metal-air batteries. However, its practical application ne- cessitates a significant cost reduction, which can be achieved in part by using new synthetic methods and im- provement of catalytic activity by increasing the density of redox active centers. This can be modulated by using polymer as the carbon and nitrogen sources. Although, superior catalytic activity of such N-doped C has been investigated in details, the electrochemical long-term sta- bility of polymer-derived doped-carbon is still unclear. Herein, in this study we generated N-doped carbon from the most recommended polymer that is comparable to the state-of-the-art materials with porosity as high as 2,086 m 2 g -1 and a nitrogen doping level of 3-4 at.%, of which 56 % is pyrrolic N, 36.1 % pyridinic and * 8% graphitic. The electrochemical characterization shows that N-doped carbon is catalytic toward oxygen reduction in an alkaline electrolyte via a favorable four-electron process, however, not stable under long-term potential scanning. The irreversible electrochemical oxidation of this material is associated with the presence of a significant content or pyrrolic and pyridinic N close to the edge of the carbon network originating from the polypyrrole precursor. These structures are less stable under operating electrochemical potential. The role of polypyrrole as the precursor of N-doped carbons has to be carefully revised since it sup- plies sufficient number of catalytic sites, but also generates unstable functionalities on the carbon surface.
Highlights
Porous doped carbons are prosperous materials due to valuable features such as relatively low production cost, high electrical conductivity, chemical and thermal stabilities, to name a few of the reasons for their becoming attractive candidates in a wide range of applications [1]
This study revealed that the electrochemical instability of PPy-derived N-doped C is correlated with structural changes of amorphous phase—for comparison, the sample derived from the commercial graphitized structures remains stable
In this work we validate the electrochemical stability of polypyrrole-derived N-doped carbon, by generating a model compound that is comparable to the current state-ofthe-art doped carbon with porous structure and a nitrogen doping level of 3–4 at.%, consisting of 56 % pyrrolic N, 36.1 % pyridinic N and only *8 % graphitic N centers
Summary
Porous doped carbons are prosperous materials due to valuable features such as relatively low production cost, high electrical conductivity, chemical and thermal stabilities, to name a few of the reasons for their becoming attractive candidates in a wide range of applications [1]. Nanostructured doped carbons have been extensively used as electrodes, electrocatalysts or catalyst supports in energy storage and conversion devices [2,3,4]. Among these potential applications, a great deal of research has been devoted to the use of porous carbons as catalysts in fuel cell technology [5]. Mater Renew Sustain Energy (2015) 4:5 alternatives to the noble-metal Pt/C system with already proven higher activity and stronger resistance against poisoning effects when comparing to the platinum [6] This remarkable property of nitrogen-doped carbon stems from its unique electronic structure compared to bare carbon. The local centers with different electron density on the catalyst surface attract and stabilize the absorbed O2, resulting in superior catalytic activity toward electrochemical oxygen reduction [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
