Accelerating the oxygen adsorption kinetics to regulate the oxygen reduction catalysis via Fe3C nanoparticles coupled with single Fe-N4 sites

Manipulating the electronic structure of Fe-N4 single-sites to accelerate the oxygen adsorption kinetics is a commendable approach to improve the oxygen reduction reaction (ORR) performance of single-atom Fe catalysts but remains a challenge. Here we propose an endogenous regulation strategy to in situ design the single-atom Fe catalyst (Fe3C@NCNTs) derived from 1,8-diaminonaphthalene, iron trichloride, and graphitic carbon nitride via Fe-N4 single-sites strongly coupled with Fe3C nanostructures, in which the combination of 1D and 2D dopedcarbon structures and the formation of Fe3C|Fe-N4 coupled sites can endow the catalyst with a considerably enhanced electrocatalytic activity and remarkable cycling stability to the ORR in Zn-air batteries. Theoretical calculations further reveal that endogenous Fe3C nanostructures can effectively activate the atomically dispersed Fe-N4 sites, narrowing the energy barriers of the rate-limiting steps of ORR to promote the ORR catalytic performance. This work provides an effective way to in situ tune the electronic structure of metal atoms to boost the ORR performance of single-atom catalysts for electrochemical energy systems.

Automated summary

This study proposes an endogenous regulation strategy to enhance the oxygen reduction reaction (ORR) performance of single-atom Fe catalysts. Theoretical calculations show that the endogenous Fe3C nanostructures can activate the atomically dispersed Fe-N4 sites, promoting the ORR catalytic performance. This work is significant for boosting the ORR performance of single-atom catalysts in electrochemical energy systems.