Porous Carbons as Supports for Iron (II) Tris(1,10‐Phenanthroline)‐Based ORR Catalyst: The Role of Morphology and Surface Chemistry

Carbon materials are widely used as supports in heterogeneous catalysis. They offer high conductivity, thermal and chemical stability, as well as a desirable porous structure that enables the use of their surface to anchor catalytically active sites. The distribution of metals within a carbon matrix enables a higher dispersion of active sites, stabilizing the atoms or nanoparticles, while ideally increasing the activity per unit mass of metal present. Investigating the synergistic combination of a metal source deposited onto different carbon materials provides a guideline for selecting support materials in catalyst design. In this work, carbons with various pore size distributions, including DUT‐108, a commercial activated carbon (ACC), and Ketjen Black EC‐600 JD, were investigated as supports for an iron–based complex, Fe(II) tris‐1,10‐phenanthroline sulfate, incorporated via incipient wetness impregnation followed by pyrolysis. The resulting iron‐doped carbon catalysts were evaluated in the oxygen reduction reaction (ORR) in alkaline media. Pore size distribution, structural descriptors, iron, and nitrogen content reveal correlations of activity, morphology, and surface chemistry. Ketjen Black was found to be the best support among the carbons investigated, resulting in a more positive onset potential, high selectivity toward the 4e ^– pathway, and twice the limiting current density compared with other carbons.