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

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Flexible zinc-air batteries (FZABs) require efficient oxygen reduction reaction (ORR) catalysts to improve energy efficiency.
• Iridium (Ir) is a highly effective ORR catalyst, but its high cost limits practical applications.
• Developing cost-effective catalysts with low noble metal loading is crucial for advancing FZAB technology.

Purpose of the Study:

• To design and synthesize novel hierarchical porous carbon nanofibers (HPCNFs) decorated with ultralow loadings of iridium nanoparticles (NPs).
• To investigate the ORR catalytic activity and stability of the synthesized Ir/FeZn-HPCNFs.
• To evaluate the performance of FZABs assembled with the developed electrocatalysts.

Main Methods:

• Hierarchical porous carbon nanofibers were synthesized using a core-shell hybrid of covalent-organic framework/metal-organic framework (COF/MOF).
• Ultralow loadings of Ir nanoparticles were incorporated onto the HPCNFs.
• The catalytic performance was assessed using electrochemical techniques, focusing on the oxygen reduction reaction (ORR).
• Flexible zinc-air batteries were assembled and tested for their discharge performance and stability.

Main Results:

• The synthesized Ir/FeZn-HPCNFs exhibited enhanced ORR performance compared to conventional catalysts.
• The use of ultralow Ir loading significantly reduced the catalyst cost while maintaining high catalytic activity.
• FZABs assembled with Ir/FeZn-HPCNFs demonstrated impressive and stable electrochemical performance.
• The hierarchical porous structure facilitated efficient mass transport and provided abundant active sites.

Conclusions:

• The developed "branch-leaf" like Ir/FeZn-HPCNFs offer a cost-effective and highly efficient electrocatalyst for FZABs.
• This approach provides a viable strategy for designing advanced catalysts by combining COF/MOF hybrids and noble metal nanoparticles.
• The study highlights the potential of nature-inspired nanostructures for next-generation energy storage devices.