Electrochemical dimerization of furfural and 5-hydroxymethylfurfural into aviation fuel precursors: Optimization and mechanistic insights

Furfural and 5-hydroxymethylfurfural are prominent biomass-derived aldehydes, offering substantial potential for sustainable fuel production. The electrochemical dimerization of these bio-derived aldehydes is investigated in this study as a novel and mild approach to carbon-chain elongation (>C6), leading to the formation of viable precursors for aviation kerosene. Compared with conventional electrochemical hydrogenation, this approach directly promotes C–C coupling without additional reagents or harsh conditions. Systematic investigations of electrode materials, applied potentials, and electrolysis duration enabled precise control over product selectivity. Notably, a Pb/CF electrode demonstrated superior catalytic performance, achieving 77.7 % selectivity for hydrofuroin from furfural and 89.8 % for 5,5′-bis(hydroxymethyl) hydrofuroin from HMF. Mechanistic analyses revealed that moderate hydrogen adsorption capacity on electrode surfaces enhances aldehyde coupling and suppresses competing hydrogenation pathways. Consequently, this mild electrochemical route offers clear advantages over thermochemical upgrading, including operational simplicity, environmental compatibility, and integration with renewable energy sources. These findings not only underscore the feasibility of electrochemical dimerization for biomass upgrading but also establish a robust basis for developing sustainable aviation fuels.