Atomically Dispersed Isolated Fe-Ce Dual-Metal-Site Catalysts for Proton-Exchange Membrane Fuel Cells.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts are promising for oxygen reduction reaction (ORR) but face limitations due to intrinsic electronic structures.
• A linear relationship between activity and intermediate adsorption energy hinders performance in traditional single-metal sites.

Purpose of the Study:

• To overcome the limitations of single-atom catalysts by modulating electronic structure.
• To break the linear relationship between catalytic activity and adsorption energy.
• To enhance oxygen reduction reaction (ORR) performance.

Main Methods:

• Constructed Fe-Ce atomic pairs to modulate the iron d-orbital electron configuration.
• Synthesized FeCe-single atom dispersed hierarchical porous nitrogen-doped carbon (FeCe-SAD/HPNC) catalyst.
• Investigated the catalyst's electronic structure and its effect on ORR intermediates.

Main Results:

• The FeCe atomic pairs altered iron's d-orbital center, weakening adsorption strength.
• The rate-determining step shifted from *OH desorption to *O > *OH.
• Achieved a high half-wave potential of 0.81 V for ORR in HClO4 solution.
• Demonstrated a maximum power density of 0.771 W cm⁻² in a H2-O2 proton-exchange membrane fuel cell (PEMFC).

Conclusions:

• The FeCe-SAD/HPNC catalyst exhibits excellent ORR activity and stability.
• Modulating electronic structure via atomic pairs is an effective strategy to enhance single-atom catalyst performance.
• The hierarchical porous structure facilitates a three-phase reaction interface for efficient fuel cell operation.