Fe-single-atom catalyst anchored on N,S-codoped carbon derived from Fe(II) complexes with three bidentate precursors for superior oxygen reduction performance

Constructing single-atom active sites for high catalytic performance remains a significant challenge due to their easy migration and agglomeration. In this study, we constructed a noble-metal-free catalyst (Fe@N PD S B PC) derived from three precursors with strong N,N or S,S-bidentate chelating abilities, effectively coordinating and anchoring Fe 2 + ions during pyrolysis to form single Fe sites dispersed on N,S-codoped porous carbon. The synergistic coordination of the three precursors endowed Fe@N PD S B PC with hierarchical porous structures, a high specific surface area (505 m 2 g −1 ) and a high N,S-codoping content (9.83 at%) compared to other carbon products (≤ 327 m 2 g −1 and 7.37 at%, respectively) prepared from any two of the three precursors. Fe@N PD S B PC demonstrated excellent oxygen reduction performance with a significantly higher half-wave potential (0.924 V), kinetic current density at 0.85 V (40.0 mA cm −2 ) and electrochemical active surface area (365 cm 2 ECSA ) and significantly better durability and methanol tolerance than the benchmark Pt/C catalyst (0.882 V, 13.3 mA cm −2 and 159 cm 2 ECSA , respectively). When used in zinc-air batteries, Fe@N PD S B PC achieved considerably higher power density (210 mW cm −2 ), specific capacity (767 mAh g zn −1 ), and longer-term cycling durability (200 h) at 5 mA cm −2 than Pt/C (148 mW cm −2 , 613 mAh g zn −1 and 55 h, respectively). Pyrolysis of Fe 2+ complex with three bidentate ligands to form single Fe atom catalyst with excellent oxygen reduction performance in zinc-air batteries. • Pyrolysis of Fe 2+ complex with three bidentate ligands to form single Fe catalyst. • The catalyst has high N,S-codoping and atomically dispersed single Fe sites. • The catalyst has superior ORR catalytic activity with E 1/2 = 0.924 V (vs. RHE). • The catalyst-based Zn-air batteries perform much better than Pt/C-based ones.