Electrochemical stability of the polymer-derived nitrogen-doped carbon: an elusive goal?

Abstract

Nitrogen-doped carbon is a promising metalfree catalyst for oxygen reduction reaction in fuel cells and metal-air batteries. However, its practical application necessitates a significant cost reduction, which can be achieved in part by using new synthetic methods and improvement 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 stability 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 supplies sufficient number of catalytic sites, but also generates unstable functionalities on the carbon surface.

Grafting of the carbon allotropes and polypyrrole via a Kevlar-type organic linker: the correlation of carbon structure/morphology with electrochemistry of the composite electrode

“…4c), its degradation is the fastest. These structures are at least thermally stable, probably due to the very small size of the carbon particles and a significantly lower degree of the carbon graphitization (amorphous carbons are less stable under the thermal, chemical or electrochemical oxidative treatment [58]). Figure 6 represents the cyclic voltammogram of the grafted material with the MWCNTs as the carbon core.…”

Biohybrid Cathode in Single Chamber Microbial Fuel Cell

“…However, Pt is not abundant, and the high cost limits its further employment as catalyst layer at the cathode. In recent years, many works focused their attention on the development of new catalyst layers, based on non-precious metal compounds [12,13,14,15,16,17], their alloys and metal-free materials [18,19,20,21,22,23,24,25]. Another class of catalysts important for ORR is comprised of aerobic bacteria, which are able to directly transfer the electrons released from the anode to molecular oxygen.…”

A Review of Carbon-Composited Materials as Air-Electrode Bifunctional Electrocatalysts for Metal–Air Batteries

“…In addition to the N-doped mesoporous carbon materials discussed above, other N-doped mesoporous carbon materials have also been obtained for MAB cathode catalysts [33][34][35][36][37][38]. For instance, a novel hierarchical N-doped carbon ORR catalyst (labeled by N:C-MgNTA) with a graphitic shell was prepared by Eisenberg et al [38].…”