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

Abstract

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_PDS_BPC) 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_PDS_BPC with hierarchical porous structures, a high specific surface area (505 m² g⁻¹) and a high N,S-codoping content (9.83 at%) compared to other carbon products (≤ 327 m² g⁻¹ and 7.37 at%, respectively) prepared from any two of the three precursors. Fe@N_PDS_BPC 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 cm²_ECSA) and significantly better durability and methanol tolerance than the benchmark Pt/C catalyst (0.882 V, 13.3 mA cm⁻² and 159 cm²_ECSA, respectively). When used in zinc-air batteries, Fe@N_PDS_BPC 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).