Electrochemical reduction hydrogenation, hydrogenolysis and dimerization of bio-derived aldehydes: A review

The efficient use of biomass is crucial for global efforts to reduce carbon emissions. Biomass-coupled electrochemical upgrading can convert low-cost biomass crude products into high-value organic molecules with minimal energy consumption. In contrast to conventional thermochemistry, which necessitates the application of heat (200–400 °C), pressure (4–20 MPa) and a hydrogen supply, electrochemical hydrogenation is conducted under relatively mild conditions. This study concentrates on the product distribution of typical biomass aldehydes, namely furfural, 5-hydroxymethylfurfural and benzaldehyde, during electrochemical reduction with varying hydrogenation depths. Additionally, it is examined the underlying mechanisms of electrochemical reduction, including hydrogenation, hydrogenolysis and dimerization by the comparison of aldehydes' thermochemical and electrochemical upgrading. Furthermore, it explores the effect of intermolecular interactions of these aldehydes on electrocatalytic reduction in mixed systems. The study expands the hydrogenation polymerization of single molecules to intermolecular hydrogenation polymerization of various aldehydes, resulting in multifunctional high-carbon organic molecules that can serve as fuel precursors. This research presents a new approach to upgrading biomass-based platform molecules, opening up new possibilities for the multifaceted application of biomass in the field of fuels.