2025/07/25 by Eliot Petitdemange, Jinjie Zhu, Angus Pedersen +8 · 1 voice
Energy · Engineering · Materials Science · #Covalent Organic Framework Applications #Electrocatalysts for Energy Conversion #Fuel Cells and Related Materials
paper · doi:10.26434/chemrxiv-2025-rsx2g
openalex publication_date 2025/07/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/14
The decoupled synthesis of Fe-NC single-site electrocatalysts, where active sites are imprinted in a porous carbon through Lewis-acid mediated pyrolysis followed by cation exchange, enables high active site density and utilization. However, current approaches often rely on small organic molecules and suffer from low synthesis yields due to the high Lewis acid-to-precursor ratios required to achieve highly porous carbons. Here, a porous organic polymer (POP) based on 2,4,6-Triaminopyrimidine is utilized as a carbon-nitrogen based scaffold for the synthesis of Fe-NC electrocatalysts. By tuning the amounts of MgCl2·6H2O used both as porogen and active site templating agent, we achieve synthetic yields exceeding 40%, a significant improvement compared to the 6% yield from the molecular analogue and the highest reported for Mg2+ templated systems. Subsequent low-temperature exchange with Fe leads to atomically dispersed FeNx, minimizing Fe aggregation. The resulting materials exhibit high specific surface areas (>1000 m2 g-1) with micro-, meso- and macropores, which promote mass transport and active site accessibility. Compared to Fe-NC synthesized via direct pyrolysis of Fe-coordinated POP, the decoupled method delivers significantly higher catalytic activity in both alkaline and acidic media, highlighting its potential for practical oxygen reduction devices.