Efficient Integration of 5-Hydroxymethylfurfural Oxidation to 2,5-Furandicarboxylic Acid with Electrochemical Reduction of CO2 to Tunable Syngas Production in a Flow Cell.

Pairing electrochemical CO₂ reduction (CO₂RR) with the oxygen evolution reaction (OER) significantly limits overall system efficiency due to the high energy demand of the OER and low product value. Here, a scalable electrochemical platform is present that couples CO₂RR with the oxidation of 5-hydroxymethylfurfural (HMF) to the high-value product 2,5-furandicarboxylic acid (FDCA). Using a bimetallic FeCo-modified Ni-anode, prepared via a Fenton-like surface treatment, achieves >95% FDCA yield and Faradaic efficiency under industrially relevant conditions by oxidizing stable Cannizzaro-derived intermediates. Integration with CO₂RR in an electrochemical flow cell enables syngas production with tunable H₂/CO ratios (0.1-4) and >92% overall Faradaic efficiency. Simultaneously, FDCA is produced at the anode with ≈89% Faradaic efficiency and yields exceeding 90%. Economic analysis indicates an 11-12% improvement in overall energy efficiency, with FDCA contributing more than 96% of the system revenue. This work establishes a scalable, energy-efficient platform for concurrent CO₂ utilization and biomass upgrading, advancing sustainable electrochemical production.