Electrochemical Dimerization of Bio-Derived Aldehydes into Aviation Fuel Precursors: Intermolecular Interactions and Cross-Coupling Effects

Aviation-fuel decarbonization remains a major challenge, motivating renewable electrochemical routes to jet-range intermediates from biomass-derived aldehydes. Individually, aldehydes such as furfural (FF), 5-hydroxymethylfurfural (HMF), and benzaldehyde (BAD) undergo electrohydrodimerization to form long-chain oxygenated polyols. In mixed systems, cross-coupling between different aldehydes yields dimers with adjustable functionality. However, selectivity in binary mixtures is difficult to control, and the mechanistic role of intermolecular interactions in directing self- versus cross-dimerization remains insufficiently defined. This work investigates FF/HMF, FF/BAD, and HMF/BAD in a three-electrode H-type cell, establishing structure-selectivity correlations and practical operating windows. In FF/HMF, conversions reach 81% (FF) and 69% (HMF) at −0.5 V vs RHE, and the mixture achieves 10 mA cm–2 at −0.29 V vs RHE compared to −0.40 V vs RHE for single-substrate benchmarks, indicating synergistic coadsorption. In FF/BAD, heterodimers constitute ∼20–30% of identified products near −0.5 V vs RHE. In HMF/BAD, Cu foam (CF) suppresses aldehyde decomposition observed on carbon paper (CP) and raises dimer selectivity up to 45%. These results show that competitive-cooperative adsorption and complementary radical stabilization govern pathway partitioning, providing a mechanistic basis to steer binary aldehydes toward cross-coupled dimers as viable jet-fuel intermediates.