Biomimetic Nanostructure Engineering of Ultralow Ir-Loading Electrocatalysts for Oxygen Reduction Reaction

Promoting the rate of the oxygen reduction reaction (ORR) is critical for boosting the overall energy efficiency of the flexible zinc-air batteries (FZABs). Inspired by nature, we designed "branch-leaf" like hierarchical porous carbon nanofibers with ultralow loadings of Ir nanoparticles (NPs) derived from covalent-organic framework/metal-organic framework (COF/MOF) core-shell hybrids. The as-obtained Ir/FeZn-hierarchical porous carbon nanofibers (HPCNFs) showcase enhanced ORR performance, and the ultralow Ir loading reduces the cost while maintaining catalytic capacity. Interestingly, the FZABs assembled with Ir/FeZn-HPCNFs deliver an impressive stable performance. This work provides a feasible approach for designing cost-effective and highly efficient electrocatalysts using in FZABs.