LAUSR

The gram-scale selective oxidation of biomass-based chemicals, in particular 5-hydroxymethylfurfural (HMF), into value-added 2,5-diformylfuran (DFF) has a high application potential but suffers from high cost, low selectivity and needs harsh reaction conditions. Besides, electrooxidation strategy requires the usage of expensive electrodes and struggles with low selectivity and efficiency, which restricts its further scale-up application. In this regard, we developed a continuous flow system through redox mediator I-/I2 for the efficient synthesis of DFF, which can accelerate the mass transfer of I- (I2) to aqueous (organic) phase and avoid over-oxidations to achieve high selectivity. After the solvent system, iodine concentration and reaction time were optimized, highly efficient DFF synthesis (selectivity: >99%) could be achieved in the electrochemical flow system using inexpensive graphite felt (GF) as electrodes. Moreover, selective HMF oxidation was paired with hydrogen evolution reaction (HER) with increased efficiency after using in-situ loaded GF-CoS2/CoS and GF-Pt electrodes. As a result, the required energy to achieve the gram-scale synthesis of DFF is significantly reduced, demonstrating the outstanding potential for large-scale production of the target product.