Recently, single-atom catalysts (SACs) have attracted broad research interest as they combine the merits of both homogeneous and heterogeneous catalysts, such as maximized atom utilization efficiency, highly catalytic activity and recyclability. However, it is still a great challenge to fabricate stable SACs because of their easy migration and agglomeration.

To overcome these challenges, the research group led by Prof. CAO Rong from Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences (CAS) developed a simple ionothermal method to fabricate atomically dispersed Fe?Nx species on porous porphyrinic triazine-based frameworks (FeSAs/PTF) with high Fe loading up to 8.3 wt %. This work was published online in ACS Energy Letters.

Spherical aberration-corrected transmission electron microscopy was performed to prove the atomically dispersed iron atoms and exclude the existence of iron nanoparticles. Element mapping reveal that elements Fe, N and C were homogeneously distributed over the entire catalyst.

In addition, X-ray absorption near-edge structure (XANES) and extented X-ray absorption fine structure (EXAFS) had been conducted to further prove the atomically dispersed iron atoms and determine the coordination environment of Fe species. It turns out that each Fe atom in FeSAs/PTF-600 is coordinated with four nitrogen atoms, thus forming the Fe-N4 active sites.

The as-prepared catalyst FeSAs/PTF-600 synthesized at 600 oC with atomically dispersed Fe-N4 active sites and good electrical conductivity exhibited highly efficient activity, methanol-tolerance and superstability for oxygen reduction reaction (ORR) in both alkaline and acidic conditions.

This study brings up a facile and general synthesis strategy to design single-atom catalysts (SACs) with exact atomistic structure of the active sites and further establish a definitive correlation between the active sites and catalytic properties, which can guide the subsequent design of future generations of SACs.

Atomically dispersed Fe-N4 Active Sites anchored on porphyrinic triazine-based frameworks were prepared by a simple ionothermal method and exhibited highly efficient activity toward oxygen reduction reaction (ORR).

Contact:

Prof. CAO Rong

Fujian Institute of Research on the Structure of Matter

Chinese Academy of Sciences

Email: rcao@fjirsm.ac.cn