Exploration of the active center structure of nitrogen-doped graphene-based catalysts for oxygen reduction reaction

Abstract

We present two different ways to fabricate nitrogen-doped graphene (N-graphene) and demonstrate its use as a metal-free catalyst to study the catalytic active center for the oxygen reduction reaction (ORR). N-graphene was produced by annealing of graphene oxide (G-O) under ammonia or by annealing of a N-containing polymer/reduced graphene oxide (RG-O) composite (polyaniline/RG-O or polypyrrole/ RG-O). The effects of the N precursors and annealing temperature on the performance of the catalyst were investigated. The bonding state of the N atom was found to have a significant effect on the selectivity and catalytic activity for ORR. Annealing of G-O with ammonia preferentially formed graphitic N and pyridinic N centers, while annealing of polyaniline/RG-O and polypyrrole/RG-O tended to generate pyridinic and pyrrolic N moieties, respectively. Most importantly, the electrocatalytic activity of the catalyst was found to be dependent on the graphitic N content which determined the limiting current density, while the pyridinic N content improved the onset potential for ORR. However, the total N content in the graphene-based non-precious metal catalyst does not play an important role in the ORR process.

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]…”

Carbon-Based Metal-Free Electrocatalysis for Energy Conversion, Energy Storage, and Environmental Protection

“…Thus, an increase in the heteroatomdoping content may not always enhance carbon-based catalyst performance [13]. In fact, the type of heteroatom dopant is of vital importance in the performance enhancement for metal-free carbon catalysts.…”

“…Because ORR, OER, and HER have been reviewed in several previously published articles [4,[10][11][12], the focus in this review will be on recent advances and new reactions (e.g., CO 2 RR, multifunctional electrocatalysis). A critical overview of efficient methods for developing carbon-based metal-free catalysts for various energy conversion/storage and environmental protection devices, including ORR in fuel cells [13][14][15][16][17], ORR and OER in metal-air batteries [18][19][20][21][22][23][24][25][26][27][28], OER and HER in water-splitting units [29][30][31], I − /I 3− reduction in dye-sensitized solar cells [32][33][34][35], and CO 2 RR in Li-CO 2 batteries [36][37][38][39][40][41][42] will then be provided. Finally, perspectives and challenges in this fast-growing and significant field are outlined.…”

Surfactant-Template Preparation of Polyaniline Semi-Tubes for Oxygen Reduction

“…Up to now, doped carbon electrocatalysts of different morphologies, such as nanoparticles [20], nanowires [21], nanotubes [22], nanorods [23], hollow nanospheres [24] and amorphous carbons [25], have been constructed by using various methods. The soft-template synthesis through self-assembly processes is among the most straightforward methods for nanostructure formation.…”