Ir-based electrocatalysts for facile ethanol oxidation reaction: effect of support, loading, and alloying with Ru

Direct ethanol fuel cells (DEFCs) offer a compelling pathway for sustainable energy conversion, yet sluggish kinetics and severe surface poisoning of conventional platinum-based anode catalysts hinder their practical adoption. Here, we present a systematic investigation of iridium-based electrocatalysts for the ethanol oxidation reaction (EOR) in acidic media, deconvoluting the independent and cooperative contributions of support identity, metal loading, and Ru alloying within a unified experimental framework. Structural and surface characterization by XRD, TEM, FT-IR, and XPS confirmed successful catalyst synthesis. It revealed systematic changes in the electronic environment of Ir upon support substitution and Ru alloying. ATO-supported Ir exhibited lower EOR activity than Ir/C, while increasing the Ir loading to 17-33 wt% partially recovered the catalytic performance. Ru alloying on carbon produced the strongest enhancement in the low-potential region, shifting the EOR onset potential to ∼0.08 V vs. RHE and delivering ∼25-30 A g_Ir ^-1 at 0.1 V. Benchmarked against commercial Pt, all Ir-based catalysts exhibit onset potentials 300-400 mV earlier and peak potentials 150-200 mV lower than Pt. These results establish electronic, geometric, and bifunctional descriptors as an integrated design strategy for next-generation DEFC anode catalysts, positioning IrRu/C as the superior candidate among the series investigated.