Nitrogen-doped carbon xerogel: A novel carbon-based electrocatalyst for oxygen reduction reaction in proton exchange membrane (PEM) fuel cells

Abstract

A low-cost, novel carbon-based electrocatalyst for oxygen reduction reaction (ORR), nitrogen-doped carbon xerogel (N-CX) was synthesized via a sol-gel polymerization method followed by a pyrolysis process. The N-CX catalyst exhibited a high activity for ORR, and a good stability in acid media. A high performance with a maximum power density of 360 mW cm À2 was achieved on a single PEM fuel cell with N-CX as the cathode electrocatalyst.As one of the key materials of PEM fuel cells, the electrocatalyst for oxygen reduction reaction (ORR) in particular plays a critical role in determining cell performance, cost and durability. The platinumbased carbon-supported electrocatalysts (e.g. Pt/C) have been considered as the most effective elecrocatalysts for ORR in PEM fuel cells due to their high activities and good stabilities. 1-9 However, the issues of high cost, scarce sources and long-term durability limit their large-scale production and hinder the commercialization of PEM fuel cells. [10][11][12][13][14] In order to decrease the cost of electrocatalysts and eliminate their dependence on noble metals, various non-noble metal catalysts have been explored recently as alternatives to the Pt-based electrocatalysts, which include chalcogenide catalysts, 15-19 transition metal macrocyclic compounds, 20-22 transition metallic oxides 23-27 and carbon-based catalysts. [28][29][30][31][32][33][34][35] In particular, carbon-based catalysts doped with the heteroatoms such as nitrogen (N) or boron (B) have been paid much attention and been proposed as typical non-noble metal catalysts for ORR 36-38 in alkaline media. Especially, since Gong et al. 37 reported the superior activity and stability of nitrogen doped carbon nanotube in alkaline solution, the heteroatom doped carbon materials have been expected to be promising alternative Pt-based catalysts. The doped carbon-based catalysts demonstrate tailored physico-chemical properties, such as structure, electrical conductivity, surface properties and oxidation stability, depending on the amount of the incorporated heteroatoms. It is also reported that the incorporated heteroatoms in the carbon structure contribute to the catalytic activities for many reactions 39-41 including the ORR in alkaline media. However, the activities and stabilities of these catalysts in acidic media are still challenging.Recently, carbon xerogels have been reported as the electrode materials for capacitors and electrocatalyst supports because of their controllable structures, high electronic conductivities, good anticorrosion properties, facile preparations and low costs. 42-51 However, they are almost inactive towards the ORR in PEM fuel cells. In this paper, a nitrogen-doped carbon xerogel (N-CX) was developed by incorporating nitrogen into the carbon xerogel and employed as an electrocatalyst for ORR in PEM fuel cells. Broader contextDue to their advantages such as fast response, high efficiency, environmental friendliness, etc., PEM fuel cells are considered as the most promising power sources for t...

Soy protein directed hydrothermal synthesis of porous carbon aerogels for electrocatalytic oxygen reduction

“…Among various carbon materials, carbon aerogels are of particular interest given that they can be easily synthesized towards uniform, low density lightweight and controllable structures M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 3 (i.e. monolith, bead, powder or thin film) with excellent mass transfer properties, low thermal conductivity and dielectric permittivity [2,3]. Structural features such as micro-, meso-and macro-porosity, arrangement of carbon network and surface functionality are controlled by the employed drying technique (i.e.…”

Nitrogen-doped carbon xerogel as high active oxygen reduction catalyst for direct methanol alkaline fuel cell

“…2b, it can be observed that the Co-NCX-20 presents an amorphous microstructure, not graphitic structure, due to the low pyrolysis temperature and the original 3D-net structure for RF resin. According to our previous work [39], this unique structure is expected to expose more planar edges and defective due to N-doping, which is supposed to offer more reactive sites for ORR [44]. Fig.…”

“…The NCX catalysts were prepared according to our previous work [39]. Briefly, 6.16 g resorcinol (R) was dissolved in 7 ml deionized water and mixed with 8.4 ml formaldehyde (F) solution (37% formaldehyde, aq.).…”

“…They are widely used as hydrogen storage materials, adsorbents, double-layer capacitor materials, and catalyst supports [35e38]. Our previous work demonstrates that the nitrogendoped carbon xerogel is promising for use as ORR catalyst in acid media [39], which was featured of high activity and superior stability in proton exchange membrane fuel cells. However, to our best knowledge, the application of nitrogendoped carbon xerogel as ORR catalyst in alkaline media was seldom report.…”

A Nitrogen‐Doped Polyaniline Carbon with High Electrocatalytic Activity and Stability for the Oxygen Reduction Reaction in Fuel Cells

“…[37] The carbon catalyst does not suffer activity degradation caused by Pt nanoparticles agglomeration and loss as Pt/C does, which maybe also contributes to their high stability. [37,38] The formation of graphitic carbon may also play a significant role in the improvement of the corrosion resistance for the carbon-based catalyst. [17] In summary, we have developed a facile approach for the synthesis of nitrogen-doped carbon electrocatalysts with polyaniline as carbon source by a polymerization process combined with further pyrolysis under an ammonia atmosphere.…”