Harnessing trace water for enhanced photocatalytic oxidation of biomass-derived alcohols to aldehydes

The photocatalytic conversion of biomass into valuable chemicals offers a more energy-efficient and low-carbon alternative to traditional thermal catalysis, representing a promising strategy for fine chemical production without relying on fossil fuels. While most studies have focused on catalyst design to improve efficiency, the precise tuning of solvents has been neglected. This study examines the conversion of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) as a representative biomass alcohol oxidation reaction, revealing a novel strategy for enhancing photocatalytic efficiency through solvent fine-tuning. The introduction of minute quantities of water into an acetonitrile solvent matrix during the HMF oxidation reaction was observed to engender pronounced enhancements in catalytic performance, with the degree of effect contingent on precise water concentration. Trace water is an active participant in the catalytic cycle, diminishing the activation energy barrier for bond cleavage and averting catalyst deactivation. This mechanism also proved applicable to other photocatalysts and various alcohol substrates, highlighting the potential of this strategy for enhancing photoenergy utilization and reaction efficiency.