In Search of the Active Site in Nitrogen-Doped Carbon Nanotube Electrodes for the Oxygen Reduction Reaction

Abstract

Nitrogen-doped carbon nanomaterials are known to exhibit good electrocatalytic activity for the oxygen reduction reaction (ORR). However, the structure of the ORR active site and optimum content of nitrogen in the carbon lattice for ORR activity remains unknown. In this study, a series of vertically aligned carbon nanotubes (VA-CNTs) with a surface nitrogen concentration of 0, 4.3, 5.6, 8.4, and 10.7 atom % is prepared by the alumina template technique and characterized with XRD, Raman spectroscopy, SEM, and XPS. Electrocatalytic ORR activity is investigated by rotating disk electrode (RDE) voltammetry. Among them, VA-CNTs with a nitrogen concentration of 8.4 atom % exhibited the best ORR performance. This is ascribed to a greater number of pyridinic-type nitrogen sites. The good performance of less expensive nitrogen-doped CNTs makes the ORR electrodes a viable alternative to platinum for energy conversion device applications.

α- and γ-Fe2O3 nanoparticle/nitrogen doped carbon nanotube catalysts for high-performance oxygen reduction reaction

“…How to simultaneously minimize the ORR procedure of a two-electron transfer with the production of H 2 O 2 as the intermediate, while maximize an efficient four-electron process to generate H 2 O as the end product, is essential for the promotion of the sluggish ORR kinetics. Although noble metal-based electrocatalysts (e.g., Pt/C) have largely elevated the efficiency of electron transfer via an ideal ORR process, the crossover effects, CO poisoning, unsatisfactory stability ARTICLES SCIENCE CHINA Materials electron distribution, becoming countless ORR active sites [21]. Undoubtedly, the N-CNTs are qualified as more favorable substrates for the anchoring of Fe 2 O 3 for catalytic ORR.…”

Highly efficient cathode catalyst layer based on nitrogen-doped carbon nanotubes for the alkaline direct methanol fuel cell

“…graphene [10,[23][24][25][26][27][28][29][30][31][32][33], carbon nanotubes [11,20,21,[34][35][36][37][38][39][40][41][42][43], carbon nanofibers [12,[44][45][46][47], mesoporous carbon [15,22], graphitic carbon [48,49], carbon spheres [19,[50][51][52][53], carbon nanocages 4 [54], flower-like carbon [55], carbon aerogel [56,57], vesicular carbon [58], nanodiamonds [59]) relatively few have been tested in actual fuel cell conditions [58,[60][61][62]…”

Nitrogen-doped graphene with enhanced oxygen reduction activity produced by pyrolysis of graphene functionalized with imidazole derivatives

“…Chemical vapor deposition (CVD) is a well-known method requiring the aid of a metal catalyst (Fe, Co, Ni compounds), and in compatible with different types of carbon precursors and nitrogen-containing reagents. Nitrogen precursors can be supplied as gas mixtures such as CO/NH 3 [98], liquid organic precursors like pyridine [100], acetonitrile [99] or nitrogen containing polymers [110].…”

“…We further characterized ORR electrocatalytic activity by RRDE measurements in comparison with a commercial Pt-C. NFW-F-900 showed remarkable ORR electrocatalytic activity even though the nitrogen content (0.57 at.%) was much lower compared to previousely reported values in literature (Table 3 in pub.IV) that usually refer to nitrogen levels higher than 3 at. % [97,110,113,131]. recently highlighted by Tian et al [129].…”

“…Several studies have demostrated the superior activity of pyridinic-N on promoting ORR 47 electrocatalyctic activity [110,113,116]. In contrast, other studies reported that N-CNTs containing larger amount of graphitic-N functionalities exhibited higher ORR activity [55,115].…”