Abstract
It is highly desired but challenging to achieve highly active single-atom Fe sites from iron-based metal-organic frameworks (MOFs) for efficient oxygen reduction reaction (ORR) due to the easy aggregation of iron species and formation of the inactive Fe-based particles during pyrolysis. Herein, a facile migration-prevention strategy is developed involving the incorporation of polyaniline (PANI) into the pores of iron porphyrinic-based MOF PCN-224(Fe) and followed by pyrolysis to obtain the single-atom Fe implanted N-doped porous carbons material PANI@PCN-224(Fe)-900. The introduced PANI inside the pores of PCN-224(Fe) not only served as protective fences to prevent the aggregation of the iron species during thermal annealing, but also acted as nitrogen sources to increase the nitrogen content and form Fe-Nx-C active sites. Compared with the pristine PCN-224(Fe) derived carbonization sample containing Fe-based particles, the carbonaceous material PANI@PCN-224(Fe)-900 without inactive Fe-based particles exhibited superb ORR electrocatalytic activity with a more positive half-wave potential, significantly improved stability in both alkaline media, and more challenging acidic condition. The migration-prevention strategy provides a new way to fabricate atomically dispersed metal active sites via pyrolysis approach for promoting catalysis.
Highlights
The increase of environmental pollution and global energy demands promotes the development of the environmentally friendly energy conversion devices to avoid the use of fossil fuels [1,2,3,4,5,6]; among these, polymer electrolyte membrane fuel cell (PEMFC) and metal-air batteries can be as promising candidates in transportation vehicles and other power applications
The self-catalysis strategy is no need to use of any other catalyst that is difficult for removal in the metal-organic frameworks (MOFs), avoiding the introduction of residues to affect the electrocatalysis
The iron ions were coordinated by the porphyrin units in PCN-224 by using postsynthesis method (PSM)
Summary
The increase of environmental pollution and global energy demands promotes the development of the environmentally friendly energy conversion devices to avoid the use of fossil fuels [1,2,3,4,5,6]; among these, polymer electrolyte membrane fuel cell (PEMFC) and metal-air batteries can be as promising candidates in transportation vehicles and other power applications. The platinum-based electrodes have been proved to be the most effective catalysts for ORR in both alkaline and acidic electrolytes [10,11,12], the high cost, scarcity, poor durability; and methanol-crossover hinder its commercialization process [11]. Tremendous efforts have been devoted to develop nonprecious metal catalysts to replace the Pt-based electrodes [13,14,15,16,17,18,19,20,21,22,23,24]. The aggregation of iron species usually occurs during the pyrolysis process, which leads to the formation of large amounts of inactive aggregates, such as iron and Fe-C nanoparticles [28]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call