LAUSR

Abstract Owing to the sluggish reaction kinetics and poor stability of cathodic catalysts for oxygen reduction reaction (ORR) in acidic media, the development of highly active and acid-stable ORR catalysts is of great practical significance. Herein, the prepared ZIF-8@ZIF-67 material, polyvinylpyrrolidone (PVP), and expanded graphite (EG) are used as precursors to prepare the ZnCo2O4@nitrogen-doped carbon-carbon nanotubes wrapped by a PVP-derived thin carbon layer anchored on the EG (ZnCo2O4@NC-CNTs@PCL/EG) as ORR catalysts. ZnCo2O4@NC-CNTs@PCL/EG-10 (weight ratio of ZIF-8@ZIF-67 to EG = 10) has an onset potential of 0.689 V (vs. SCE), which is comparable with that of commercial Pt/C (0.706 V) in the acid electrolyte. After acid pickling, the spinel ZnCo2O4 as the core is stably and uniformly encapsulated by the NC-CNT skeleton and can fully use the highly active Co2+ sites to boost the 4e– ORR process with a strong methanol resistance. ZnCo2O4@NC-CNTs@PCL/EG-10 shows strong stability and methanol tolerance (a decline of 3.21%) after 3600 s, which are better than those of commercial Pt/C (29 mV and 4.06%). The ORR durability is attributed to the PCL shell that avoids the corrosion of active ZnCo2O4 and N-species. Therefore, it provides a new idea for designing a spinel-based ZIF derivative as stable ORR catalysts in acid media.