Highly Accessible Atomically Dispersed Fe-Nx Sites Electrocatalyst for Proton-Exchange Membrane Fuel Cell

Atomically dispersed transition metal-N-x sites have emerged as a frontier for electrocatalysis because of the maximized atom utilization. However, there is still the problem that the reactant is difficult to reach active sites inside the catalytic layer in the practical proton exchange membrane fuel cell (PEMFC) testing, resulting in the ineffective utilization of the deeply hided active sites. In the device manner, the favorite structure of electrocatalysts for good mass transfer is vital for PEMFC. Herein, a facile one-step approach to synthesize atomically dispersed Fe-N-x species on hierarchically porous carbon nanostructures as a high-efficient and stable atomically dispersed catalyst for oxygen reduction in acidic media is reported, which is achieved by a predesigned hierarchical covalent organic polymer (COP) with iron anchored. COP materials with well-defined building blocks can stabilize the dopants and provide efficient mass transport. The appropriate hierarchical pore structure is proved to facilitate the mass transport of reactants to the active sites, ensuring the utilization of active sites in devices. Particularly, the structurally optimized HSAC/Fe-3 displays a maximum power density of up to 824 mW cm(-2), higher than other samples with fewer mesopores. Accordingly, this work will offer inspirations for designing efficient atomically dispersed electrocatalyst in PEMFC device.

Automated summary

The study introduces a facile method for synthesizing atomically dispersed Fe-N-x species on hierarchically porous carbon nanostructures as an efficient and stable catalyst for oxygen reduction in acidic media for proton exchange membrane fuel cells. The designed hierarchical pore structure facilitates mass transport and utilization of active sites, leading to higher power density in devices.