FeCo-SN-C dual-site catalyst with high stability and oxygen reduction activity

FeCo-N-C is considered a promising electrode material for hydrogen fuel cells. However, its oxygen reduction reaction (ORR) performance is limited by the strong adsorption of intermediates. In this work, we regulated the adsorption of “metal-intermediates” by modulating the interaction between the metal and support. The sulfur atoms were introduced to modify the periphery of the M-N x sites, and an atom-dispersed bimetallic site micro-mesoporous catalyst (FeCo-SN-C) was synthesized. The S dopant enhances the bonding between the metal catalytic sites and the support, which weakens the adsorption of ORR intermediates on catalytic sites, resulting in exceptional stability and ORR activity of the catalyst. ORR tests showed that FeCo-SN-C in 0.1 M KOH exhibited superior half-wave potential (0.863 V vs. RHE), which outperformed Pt/C (0.833 V), along with high stability and methanol tolerance. Theoretical calculations demonstrated that the doping of S effectively shifted the 3d electron orbital of the Fe site to a deeper level, optimized the adsorption and desorption energy barriers of the key oxygen-containing intermediate (∗OH), and promoted the ORR. Additionally, the Zn-air batteries based on FeCo-SN-C exhibited excellent discharge performance and durability. This study provides insights and solutions for the rational design of TM-N-C catalysts to enhance their activity and stability.