Acetic acid (AA), an important commodity chemical, is produced via methanol carbonylation, emitting one ton of CO₂ per ton of product. As a sustainable alternative, we report the electrochemical oxidation of bioethanol to selectively produce AA using a novel Pd-Sn alloy catalyst with nanodendritic morphology supported on nickel foam (PdSn@NF). The catalyst was synthesized via electrodeposition, and the presence of ammonium chloride in the deposition bath was found to critically affect the Pd-to-Sn ratio and, consequently, the catalyst performance. The vital role of catalyst structure, surface composition, and morphology on the activity and selectivity of PdSn@NF towards the EOR was revealed by X-ray diffractometry, emission spectroscopy, and electron microscopy. Specifically, the nanodendritic morphology of the PdSn@NF resulted in the formation of highly active undercoordinated sites, while in situ Raman spectroscopy suggested that Sn helps mitigate CO poisoning – likely a result of a lowered d-band center. Due to the strong synergy between the structural and electronic properties of PdSn@NF, ~100% faradaic efficiency (FE) to AA at 400 mA cm-2 was achieved with lab-grade ethanol (LGE) in an H-type cell. In continuous flow operation, the FE declined due to product accumulation on active sites; however, this was mitigated by employing current pulses to remove surface-bound products. An optimized pulsing protocol restored ~100% FE of AA for LGE and achieved ~94% FE with bioethanol at 400 mA cm-2 despite the presence of fermentation impurities. This study underscores the promise of PdSn@NF as a highly selective and industrially relevant electrocatalyst for sustainable AA production.
