Fabrication of bimetallic Co/Zn leaf blade structure template derived Co3O4-ZIF/Zn and its ORR catalytic performance for MFC

Abstract Background The design of highly active non-noble metal oxidation reduction catalysts (ORR) for microbial fuel cell (MFC) has always been a challenge. The aim of this study is to develop a highly active low cost cobalt-based ORR catalyst for MFCs cathode. Method Herein, a series of highly active nitrogen doped Co3O4-ZIF/Zn-T catalysts with different calcination temperatures (T) were prepared using bimetallic Co/Zn leaf blade structure Co-ZIF/Zn-67 as template. The Co3O4-ZIF/Zn-T catalysts were characterized by various methods, and the effect of T on the structure and ORR performance of MFC catalyst were studied. Significant findings The results showed that the Co3O4-ZIF/Zn-T derived from bimetallic Co/Zn leaf blade structure Co-ZIF/Zn-67 template exhibited better ORR performance than Co3O4-ZIF-400 derived from the dodecahedral structure Co-ZIF-67 template. The bimetallic Co/Zn Co-ZIF/Zn-67 template promotes more uniformly distributed mesopores, high N content and abundant smaller active Co3O4 sites due to its particular structure and the isolation effect of Zinc. Among Co3O4-ZIF/Zn-T catalysts, the Co3O4-ZIF/Zn-400 calcined at 400 °C demonstrated the highest ORR performance (onset potential was 0.082 V and MFC power density was 656.9 mw/m2), which was much higher than Co3O4-ZIF-400 (0.027 V and 402.8 mw/m2). The output voltage of MFC with Co3O4-ZIF/Zn-T exhibited no significant downward trend in 30 days stability test, indicating that the Co3O4-ZIF/Zn-400 catalyst has great stability.