Critical role of iron carbide nanodots on 3D graphene based nonprecious metal catalysts for enhancing oxygen reduction reaction. (10th August 2018)

• Record Type: Journal Article
• Authors: Zhang, Xiaoran; Lyu, Dandan; Mollamahale, Yaser Bahari; Yu, Feng; Qing, Ming; Yin, Shibin; Zhang, Xinyi; Tian, Zhi Qun; Shen, Pei Kang
• Is Part Of: Electrochimica acta. Volume 281(2018)
• Page Start: 502
• Page End: 509
• Publication Date: 2018-08-10
• Subjects: Exposed iron carbide -- Encapsulated iron carbide -- Iron-nitrogen-carbon materials -- 3D graphene -- Oxygen reduction reaction; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.05.206
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Iron-nitrogen-carbon materials (Fe-N-C) are considered as one of the most promising none precious candidates for oxygen reduction reaction. However, the role of iron carbides, one of the important accompanied species in Fe-N-C catalyst for oxygen reduction reaction, remains controversial. Herein, two different types of 3D graphene-based Fe-N-C catalysts with exposed and encapsulated Fe carbides were synthesized via pyrolysis of self-polymerization compounds of 2, 6-Diaminopyridine using Fe(OH)3 and FeCl3 as both initiators and Fe sources, respectively. Interestingly, Mössbauer spectroscopy and X-ray photoelectron spectroscopy measurements show that both catalysts are composed of same Fe species with Fe II N4 /C, iron carbide, iron nitride, metallic iron where the proportion of each corresponding component is similar. However, there is a big gap between the two catalysts in catalytic performance for oxygen reduction reaction. The kinetic current densities of the former catalyst (3.565 mA cm −2 ) at 0.9 V vs .RHE is 4.68 times and 1.50 times higher than that of the latter (0.7617 mA cm −2 ) and Pt/C catalyst (2.376 mA cm −2 ), respectively. This sharp contrast directly identifies the critical role of exposed Fe carbides nanodots on Fe-N-C in promoting Fe-N-C activity for oxygen reduction reaction. The new discovery brings a new insight into developing advanced none precious metal catalysts.