Core-shell template derived porous 3D-Fe/Fe2O3@NSC composites as high performance catalysts for aqueous and solid-state rechargeable Zn-air batteries

Exploiting inexpensive and highly efficient catalysts used for rechargeable aqueous and solid-state Zn-air batteries is of great significance in this energy-dominated society, especially in this energy crisis period. However, the widespread application of Zn-air battery is constrained by the cathode catalysts. Therefore, the establishment of cost-effective catalysts can truly propel the commercialization process of Zn-air battery. In this work, we employ the template thermolysis-transformation oxidation strategy to construct the three-dimension carbon encapsulated Fe/Fe2O3 heterojunction composites to improve the electrochemical performance with N, S co-doped [email protected] core–shell materials as thermolysis templates followed by low temperature mild oxidation. Owing to the decomposition and ion migration of Zn-NTA nuclear from internal area of templates, the 3D-Fe/Fe2O3@NSC catalysts are observed to possess loose and porous configuration with plentiful channels, which is in favor of the improvement of mass/O2-containing intermediate transfer, so as to achieve a high performance. Theoretical calculation results disclose that the formation of heterojunction is in favor of optimizing the electronic configuration and reducing the reaction barriers. The optimal 3D-Fe/Fe2O3@NSC-900 catalysts embrace a high ORR performance with the half-wave potential of 0.88 V and a low potential difference between ORR and OER of 0.718 V. Consequently, the 3D-Fe/Fe2O3@NSC-900 based rechargeable liquid and all-solid-state Zn-air batteries exhibit remarkable stability (cycle time greater than 250 h and 155 h) and excellent power density of 195.85 and 97.73 mW.cm−2, respectively. In summary, this work provides a potential strategy to construct an efficient and cost-effective electrocatalyst toward practical applications.