Robust bifunctional oxygen electrocatalyst with a “rigid and flexible” structure for air-cathodes

• Main Authors: Fu, Gengtao, Jiang, Xian, Chen, Yifan, Xu, Lin, Sun, Dongmei, Lee, Jong-Min, Tang, Yawen
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Chemical engineering; Oxygen Electrocatalyst; Air-cathodes
• Online Access: https://hdl.handle.net/10356/88259; http://hdl.handle.net/10220/45704
• Institution: Nanyang Technological University

The development of highly active air-cathodes with robust stability and a low price is of crucial significance for rechargeable Zn–air batteries and remains a great challenge. Herein, for the first time, we report a “rigid and flexible” material consisting of three-dimensional (3D) porous nickel-manganese oxide (Ni6MnO8) coupled with 1D ultrathin Au nanowires (Au-NWs) as an efficient bifunctional oxygen electrocatalyst, adopting α-naphthol-Au(III) as a precursor of Au-NWs and pre-formed Ni6MnO8 as a support. Ni6MnO8 acts not only as a robust carbon-free support that is stable in alkaline electrochemical conditions, but also as a highly active component for the oxygen evolution reaction (OER), while flexible Au-NWs contribute to the excellent oxygen reduction reaction (ORR) activity and act as a flexible conductive electronic network. The coupling of Ni6MnO8 and Au-NWs plays a complementary role in the two types of oxygen electrocatalytic reactions. Accordingly, their advantages have been optimally harnessed while overcoming their deficiencies. Moreover, a Zn–air battery assembled with such a rigid and flexible air-cathode has lower charge and discharge overpotentials and a higher cyclic stability than those with a mixed Pt/C+RuO2 catalyst.