“…The utilization of metal–organic frameworks (MOFs) is prevalent in the production of precursors for N-doped carbon materials. , Zeolitic imidazolate frameworks (ZIFs), representative MOFs, possess excellent porosity and active area and an adjustable surface chemistry structure. , Heteroatoms (Fe, Co, Ni, and Cu) of ZIFs can enrich the coordination condition and improve the ORR activity. − In addition, transition-metal oxides draw more concern due to high catalytic activity. Cobalt oxide (CoO x ) in the carbon substrate is regarded as an efficient ORR catalyst, contributing to excellent structural stability and active area .…”