Robust N-doped carbon aerogels strongly coupled with iron – cobalt particles as efficient bifunctional catalysts for rechargeable Zn – air batteries

• Main Authors: Fu, Gengtao, Liu, Yu, Chen, Yifan, Tang, Yawen, Goodenough, John B., Lee, Jong-Min
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2020
• Subjects: Engineering::Chemical engineering; N-doped; Zn–air Batteries
• Online Access: https://hdl.handle.net/10356/141087
• Institution: Nanyang Technological University

The rational design of highly-active and stable reversible oxygen electrocatalysts for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) plays a key role in rechargeable metal–air batteries, yet remains a great challenge. Herein, a novel dual-crosslinked hydrogel strategy is proposed to synthesize a new type of carbon aerogel that anchors the iron–cobalt (FeCo) particles as a bifunctional oxygen catalyst. The proposed hydrogel composed of an organic/inorganic network can be easily obtained by initiating sol–gel polymerization of cyanometalates, chitosan and graphene oxide. After pyrolysis, FeCo nanocrystals can be in situ uniformly immobilized within the N-doped “dual-network” carbon aerogels (FeCo/N-DNC) with a robust 3D porous framework. When used as an electrocatalyst, the newly developed FeCo/N-DNC aerogels exhibit a positive onset potential (0.89 V) and half-wave potential (0.81 V) for the ORR and a low overpotential (0.39 V) at 10 mA cm−2 for the OER, while presenting excellent electrochemical stability after being tested for 10 000 s. More importantly, the FeCo/N-DNC driven Zn–air battery reveals a smaller charge/discharge voltage gap, higher power/energy density and better cycling stability than the costlier Pt/C + RuO2 mixture catalyst. Our findings provide a facile and feasible synthetic strategy for obtaining highly active and stable electrocatalysts.