Synergistic integration of 2D TiN/TiC and Fe single atoms for high-performance and durable oxygen reduction catalysis

Iron-based single-atom (SA) catalysts offer a promising alternative to noble-metal catalysts for the oxygen reduction reaction (ORR), yet their limited intrinsic activity and durability hinder practical energy device applications. Herein, we introduce a novel TiN/TiC-supported Fe SA catalyst (TiNC/Fe–NC) with a hierarchical heterostructure that synergistically enhances Fe–Nx site activity and accessibility. The TiNC/Fe–NC catalyst achieves outstanding ORR performances, with half-wave potentials (E1/2) of 0.852 V in acidic media and 0.942 V in alkaline media. Theoretical simulations reveal that strong electronic interaction and efficient charge transfer between TiNC and Fe–Nx sites optimize the adsorption energetics of key ORR intermediates, driving the enhanced activity. Remarkably, TiNC effectively scavenges reactive oxygen radicals generated at the Fe centers, ensuring exceptional durability with a minimal 28 mV loss in E1/2 after 10,000 cycles at 80 °C in acid media. In practical applications, TiNC/Fe–NC delivers peak power densities of 306 mW cm−2 in zinc-air battery and 732 mW cm−2 in proton exchange membrane fuel cells, with remarkable long-term stability. This work establishes TiNC/Fe–NC as a high-performance, durable catalyst for advanced energy storage and conversion technologies.