Simultaneously Crafting Single‐Atomic Fe Sites and Graphitic Layer‐Wrapped Fe3C Nanoparticles Encapsulated within Mesoporous Carbon Tubes for Oxygen Reduction

Abstract The rational design and facile synthesis of 1D hollow tubular carbon‐based materials with highly efficient oxygen reduction reaction (ORR) performance remains a challenge. Herein, a simple yet robust route is employed to simultaneously craft single‐atomic Fe sites and graphitic layer‐wrapped Fe 3 C nanoparticles (Fe 3 C@GL NPs) encapsulated within 1D N‐doped hollow mesoporous carbon tubes (denoted Fe‐N‐HMCTs). The successional compositional and structural crafting of the hydrothermally self‐templated polyimide tubes (PITs), enabled by Fe species incorporation and acid leaching treatment, respectively, yields Fe‐N‐HMCTs that are subsequently exploited as the ORR electrocatalyst. Remarkably, an alkaline electrolyte capitalizing on Fe‐N‐HMCTs achieves excellent ORR activity (onset potential, 0.992 V; half‐wave potential, 0.872 V), favorable long‐term stability, and strong methanol tolerance, outperforming the state‐of‐the‐art Pt/C catalyst. Such impressive ORR performances of the Fe‐N‐HMCTs originate from the favorable configuration of active sites (i.e., atomically dispersed Fe‐N x sites and homogeneously incorporated Fe 3 C@GL NPs) in conjunction with the advantageous 1D hollow tubular architecture containing adequate mesoporous surface. This work offers a new view to fabricate earth‐abundant 1D Fe‐N‐C electrocatalysts with well‐designed architecture and outstanding performance for electrochemical energy conversion and storage.