The development of efficient and sustainable nonprecious metal catalysts for the oxygen reduction reaction (ORR) is central to advancing next‐generation fuel cells and metal‐air batteries. Fe‐N‐C catalysts derived from biomass have emerged as promising candidates, yet the influence of activation chemistry on the active‐site formation and electrocatalytic performance remains insufficiently explored. Here, we unveil how KOH (strong base) and ZnCl 2 (Lewis acid) modulate the chemical activation of wine grape pomace, a readily available agri‐food residue, to generate Fe‐N‐C electrocatalysts through a one‐step synthesis without external nitrogen precursors. KOH activation promotes extensive micro‐ and mesoporosity and favors the in situ development of well‐coordinated Fe‐N x moieties, yielding a large electrochemically active surface area and a high ORR onset potential of 0.87 V versus reversible hydrogen electrode, comparable to leading biomass‐derived Fe‐N‐C catalysts. In contrast, ZnCl 2 activation reduced the density of active sites, resulting in diminished ORR activity. This work provides insight into how activation pathways govern porosity evolution, Fe‐N x site formation, and ORR performance. More broadly, it demonstrates the effective valorization of winemaking residues into functional electrocatalysts, offering a scalable and sustainable route for materials design in electrochemical energy conversion technologies.
Flores‐Gómez et al. (Fri,) studied this question.