Unraveling the high-activity nature of Fe-N-C electrocatalysts for the oxygen reduction reaction: the extraordinary synergy between Fe-N and FeN

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 7; no. 19; pp. 11792 - 1181
• Main Authors: Ao, Xiang, Zhang, Wei, Li, Zhishan, Lv, Lin, Ruan, Yunjun, Wu, Hong-Hui, Chiang, Wei-Hung, Wang, Chundong, Liu, Meilin, Zeng, Xiao Cheng
• Format: Journal Article
• Language: English
• Published: 15.05.2019
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta02338k

The scarcity and weak durability of precious metal catalysts are among the biggest obstacles to achieving cost-effective electrocatalysts in fuel cells and metal-air batteries. Hence, it is imperative to develop low-cost non-precious metal catalysts with comparable oxygen reduction reaction (ORR) activity to precious metal catalysts. Herein, we report a highly effective strategy for the facile synthesis of Fe/N-functionalized 3D porous carbon networks. A major advantage of the newly designed catalyst is that ultrafine Fe 4 N nanoparticles are grown and uniformly mounted on the carbon framework upon pyrolysis treatment at 800 °C, and co-exist with numerous in situ formed Fe-N 4 moieties in the carbon matrix, being evidenced by using X-ray absorption and photoelectron spectroscopy. The new electrocatalysts exhibit high ORR activity, comparable/superior to that of the state-of-the-art Fe/N-carbon based catalysts reported to date. Specifically, the catalysts show a half-wave potential of 0.890 V ( vs. RHE) and a limited current density of 6.18 mA cm −2 . By resorting to experimental measurements and density-functional theory (DFT) calculations, the synergistic effects between Fe-N 4 moieties and the Fe 4 N support are identified for the first time, which play a key role in boosting the catalytic performance of the Fe/N-functionalized porous carbon networks. Fe 4 N can play a decisive role in boosting the catalytic performance of Fe-N 4 coordination sites.