Coupling of CO₂ electroreduction and biomass electrooxidation: challenges, design principles, and perspectives

Sustainable carbon management through innovative strategies is essential to address the dual crises of climate change and resource scarcity. Electrochemical CO₂ reduction reaction (CO₂RR) and biomass electrooxidation (BEO) represent two promising pathways for converting CO₂ and renewable biomass into valuable chemicals. While previous reviews have broadly covered replacing the energy-intensive anodic oxygen evolution reaction (OER) for CO₂RR, they often lack an integrated analysis of the complementary challenges and design principles for CO₂RR & BEO coupling system. This review fills this gap by critically analyzing their core key limitations, notably the high energy cost of OER in CO₂RR and the low economic return from the hydrogen evolution reaction (HER) in BEO; meanwhile, the design principles, e.g., potential matching, pH and product compatibility, for the couple system are proposed. Moreover, coupled systems that effectively exploit the complementary nature of CO₂RR & BEO are systematically presented, including CO₂RR paired with the oxidation of biomass-derived molecules and other substrates (e.g., glucose, alcohols, aldehydes, methane, chlorides, sulfides) and BEO coupled with other cathodic reductions (e.g., furfural, 4-nitrophenol). Meanwhile, their compatibility in term of potential, pH and product were analyzed and compared. Finally, future research directions are outlined, with emphasis on innovative catalysts design, system-level optimization, and scalable implementation. This work provides a focused perspective on advancing sustainable resource utilization through electrochemical coupling.