Electroenzymatic cascade catalysis for efficient reduction of furfural to furfuryl alcohol: In situ cofactor regeneration regulated by cobalt porphyrin

Dual-functional interface isolates ADH and Rh mediator for enhanced stability. • In situ FT-IR captures Rh H formation during electrochemical NADH regeneration. • DFT confirms CoTPP promotes Rh-mediated NADH regeneration. • Integrated cascade enables efficient, selective, and durable furfural reduction. The efficient utilization of biomass resources is a key driver of green and sustainable development. Although electroenzymatic cascade catalysis combines the energy supply of electrocatalysis with the selectivity of enzymatic catalysis, its application is limited by factors such as coenzyme regeneration efficiency, electron mediator stability, and enzyme activity retention. To address these issues, an efficient electroenzymatic catalytic system was constructed for the reduction of furfural to furfuryl alcohol in this work. A hydrophilic polyethyleneimine/dopamine hydrochloride layer was formed on carbon cloth to firmly anchor the rhodium complex mediator (M), thereby reducing the adverse influence of free mediator on enzyme activity. Cobalt porphyrin-modified 3%CoTPP@ZIF-8 was used as the immobilization matrix for alcohol dehydrogenase (ADH), where the confined pore environment improved enzyme stability and promoted substrate enrichment. Structural characterization and electrochemical testing indicate that 3% CoTPP@ZIF-8 exhibits a good balance between charge transfer, active site exposure, and NAD + reduction efficiency. Under −0.8 V (vs. Ag/AgCl), the NADH conversion reached 86% within 2 h. Based on ADH, the calculated TON enzyme and TOF enzyme for furfuryl alcohol production were approximately 21,053 and 3509 h −1 , respectively. The electrode maintained a stable current over 45 h of continuous operation, and the yield of NADH remained around 80% after eight cycles, demonstrating favorable performance in the cascade reaction. In-situ electrochemical FT-IR spectroscopy and DFT calculations revealed that CoTPP optimized the electronic structure, lowered the energy barrier for Rh H intermediate formation and NAD + adsorption, and cooperated with M to accelerate in situ NADH regeneration. Ultimately, coupling this system with immobilized ADH can drive the conversion of furfural to furfuryl alcohol. This provides an experimental foundation for developing systems that couple electrochemical coenzyme regeneration with enzymatic conversion. Download: Download high-res image (150KB) Download: Download full-size image