Ultra-small Fe2N nanocrystals embedded into mesoporous nitrogen-doped graphitic carbon spheres as a highly active, stable, and methanol-tolerant electrocatalyst for the oxygen reduction reaction. (June 2016)

• Record Type: Journal Article
• Authors: Xiao, Junwu; Xu, Yangyang; Xia, Yating; Xi, Jiangbo; Wang, Shuai
• Is Part Of: Nano energy. Volume 24(2016:Jun.)
• Page Start: 121
• Page End: 129
• Publication Date: 2016-06
• Subjects: Iron nitrides -- Mesoporous -- Nitrogen-doped graphitic carbon -- Electrocatalysis -- Oxygen reduction reaction; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2016.04.026
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: A low-cost, highly active, stable, and methanol tolerant electrocatalyst towards the oxygen reduction reaction (ORR) is extremely desirable for promoting the commercialization of fuel cells. Herein, we reported a facile two-step pyrolysis and acid leaching process to synthesize a high performance ORR electrocatalyst, where ultra-small Fe2 N nanocrystals were incorporated into mesoporous nitrogen-doped graphitic carbon spheres (MNGCS). The Fe2 N/MNGCS electrocatalysts with difference Fe2 N contents and BET surface areas were obtained via altering the acid leaching time, and all exhibited the apparent electrocatalytic activity. The optimized ORR activity was achieved over (Fe2 N/MNGCS)4 with the positive half-wave potentials (0.881 V vs RHE), high selectivity (4 e − process), excellent long-term stability (95.2% of the initial current remaining after 60, 000 s of continuous operation) and good tolerance against methanol-crossover effect (94.9% of the current retained prior to 4.0 M methanol injection) in alkaline media, which even was more superior to that of commercial Pt/C catalyst. The remarkable ORR activity was originated from the cooperative effect of ultra-small Fe2 N nanocrystals and MNGCS, where the balance of catalytic active site density, mesoporous structure, BET specific surface area, and electron conductivity played a key role in determining the ORR performance. Graphical abstract: Highlights: A facile approach is proposed to synthesize ultra-small Fe2 N nanocrystals/MNGCS. The Fe2 N content and BET surface area of Fe2 N/MNGCS can be adjusted by altering the acid etching time. The optimized Fe2 N/MNGCS catalyst demonstrates better ORR performance than 10 wt% Pt/C catalyst. Such excellent performance is ascribed to the rational balance of the density of Fe–N/C active sites, and the transport of electron and electrolyte ion.