FeNC Electrocatalysts with Densely Accessible FeN4 Sites for Efficient Oxygen Reduction Reaction. (17th June 2021)

• Record Type: Journal Article
• Authors: Zhou, Yazhou; Chen, Guangbo; Wang, Qing; Wang, Ding; Tao, Xiafang; Zhang, Tierui; Feng, Xinliang; Müllen, Klaus
• Is Part Of: Advanced functional materials. Volume 31:Number 34(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-17
• Subjects: Fe N C catalysts -- nitrogen‐rich molecules trapping -- oxygen reduction reaction -- proton exchange membrane fuel cells -- site density; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202102420
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: The development of iron and nitrogen co‐doped carbon (FeNC) electrocatalysts for the oxygen reduction reaction (ORR) in proton‐exchange membrane fuel cells (PEMFCs) is a grand challenge due to the low density of accessible FeN4 sites. Here, an in situ trapping strategy using nitrogen‐rich molecules (e.g., melamine, MA) is demonstrated to enhance the amount of accessible FeN4 sites in FeNC electrocatalysts. The melamine molecules can participate in the coordination of Fe ions in zeolitic imidazolate frameworks to form FeN6 sites within precursors. These FeN6 sites are then converted into atomically dispersed FeN4 sites during a pyrolytic process. Remarkably, the FeNC/MA exhibits a high single‐atom Fe content (3.5 wt.%), a large surface area (1160 m 2 g −1 ), and a high density of accessible FeN4 sites (45.7 × 10 19 sites g −1 ). As a result, FeNC/MA shows a much enhanced ORR activity with a half‐wave potential of 0.83 V (vs the reversible hydrogen electrode) in a 0.5 m H2 SO4 electrolyte solution and a good performance in a PEMFC system with an activity of 80 mA cm −2 at 0.8 V under 1.0 bar H2 /air. This work offers a promising approach toward high‐performance carbon‐based ORR electrocatalysts. Abstract : An in situ trapping strategy using nitrogen‐rich molecules is developed for the preparation of Fe–N–C electrocatalysts with a high site density of FeN4 active sites (45.7 × 10 19 site g −1 ). The optimized FeNC offers outstanding performance for the oxygen reduction reaction, delivering a good performance in the H2 /Air proton exchange membrane fuel cell as the cathode catalyst.