Engineering iron-group bimetallic nanotubes as efficient bifunctional oxygen electrocatalysts for flexible Zn–air batteries
Yanli Niu, Shuaiqi Gong, Xuan Liu, Xu Chen, Mingze Xu, Shi‐Gang Sun, Zuofeng Chen
Abstract
Air cathode performance is essential for rechargeable zinc–air batteries (ZABs). In this study, we develop a self-templated synthesis technique for fabricating bimetallic alloys (FeNi3), bimetallic nitrides (FeNi3N) and heterostructured FeNi3/FeNi3N hollow nanotubes. Owing to its structural and compositional advantages, FeNi3/FeNi3N exhibits remarkable bifunctional oxygen electrocatalytic performance with an extremely small potential gap of 0.68 V between the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Theoretical calculations reveal reduced Gibbs free energy for the rate-limiting O–O bond formation during OER due to the self-adaptive surface reconfiguration, which induces a synergistic effect between Fe(Ni)OOH developed in situ on the surface and the inner FeNi3/FeNi3N. ZAB fabricated using the FeNi3/FeNi3N catalyst shows high power density, small charge/discharge voltage gap and excellent cycling stability. In addition to its excellent battery performance, the corresponding quasi-solid-state ZAB shows robust flexibility and integrability. The synthesis method is extended to prepare a CoFe/CoFeN oxygen electrocatalyst, demonstrating its applicability to other iron-group elements.