Nitrogen chemistry and pore hierarchy direct ORR pathways in polyazine–derived carbon foamsŠetka, Milena (Avtor) Kotnik, Tomaž (Avtor) Vladušić, Roko (Avtor) Rantaša, Matjaž (Avtor) Bele, Marjan (Avtor) Surca, Angelja Kjara (Avtor) Smiljanić, Milutin (Avtor) Hodnik, Nejc (Avtor) Kovačič, Sebastijan (Avtor) Hierarchically porous, high surface area, nitrogen-rich carbon foams were prepared by carbonizing aromatic and aliphaticpolyazine-based precursors. By varying precursor chemistry, nitrogen speciation and pore hierarchy were independently tuned,yielding specific surface areas up to 2874 m2⋅g−1 and nitrogen contents between 0.3 and 6.2 wt %. As a use case, the foamswere evaluated as electrocatalysts for the oxygen reduction reaction (ORR) in acidic medium. AliPAZ-CF exhibits a morepositive onset potential (0.60 V vs. RHE), a current density of 1.1 mA⋅cm−2 at 0.4 V and an H 2 O2 selectivity of 78% reflectingdistinct ORR pathway preferences arising from differences in nitrogen chemistry and pore hierarchy. CO 2 activation increasedmicroporosity and specific surface area but reduced total nitrogen content and H2 O2 selectivity, whereas subsequent NH3 treatmentrestored nitrogen functionalities, shifted the onset positively and promoted the 4e− ORR pathway. Correlating Raman andx-ray photoelectron spectroscopy with electrochemistry indicates that pyrrolic/hydrogenated-pyridinic nitrogen embedded inhierarchical micro/meso/macroporous frameworks favors the selective 2e− ORR to H2 O2 , while higher pyridinic nitrogen contentcombined with increased microporosity directs the reaction toward H2 O. These results establish mechanistic design rules that linknitrogen configuration and hierarchical porosity to control of the ORR pathway in metal-free carbon catalysts.Wiley20262026-08-06 13:29:07Članek v reviji99183UDK: 66COBISS_ID: 287142147DOI: 10.1002/cctc.70940ISSN pri članku: 1867-3899sl© 2026 The Author(s)