Electrocatalytic Valorization of Bio-based 2,5-Furandicarboxylic Acid: Selective Ring-Opening Hydrogenation to 2-Hydroxyadipic Acid over Nanostructured Bismuth

Abstract

The reductive conversion of biomass-derived 2,5-furandicarboxylic acid (FDCA) offers a sustainable, atom-economical pathway to key platform chemicals, such as 2-hydroxyadipic acid (HAA). While traditional thermocatalytic routes rely on energy-intensive, high-pressure hydrogen, electrocatalytic FDCA reduction reaction (e-FDCArr) emerges as a safer, low-carbon alternative. However, HAA synthesis via e-FDCArr has, until now, remained elusive. Herein, we report an efficient e-FDCArr process utilizing a metallic bismuth nanosheet electrode assisted by quaternary alkyl ammonium salts (QAS) in acidic media. A synergy of systematic electrolysis, multi-modal physical characterization, and multi-scale computational modeling reveal that bismuth serves as the essential catalytic center, while specific symmetric, long alkyl chains QAS cations serve a dual role: they passivate the bismuth surface against acid-driven dissolution and act as a structural template that directs FDCA adsorption into a quasi-vertical configuration. This specific orientation facilitates the exposure of the reactive oxygen site of FDCA directly to the bismuth surface for electron acquisition, driving a spontaneous, proton-coupled electron transfer and ring-opening process. Under optimized conditions, the bismuth nanosheet electrode was demonstrated, for the first time, to exhibit a remarkably high HAA yield (75.5 ± 3.3%) and selectivity (88.6 ± 3.9%) at -10 mA cm^-2. This study establishes a rational design strategy for achieving highly selective and energy-efficient chemical synthesis, substituting the hazardous fossil-derived reagents and pressurized hydrogen typical of conventional thermocatalysis with sustainable, renewable feedstocks