CO₂ Utilization and Fixation in Biomass-Derived Furanics Conversion: Thermochemical and Electrochemical Pathways

Carbon dioxide (CO₂) is the main greenhouse gas (GHG) released by human activities. The substitution of fossil resources by biomass as a bio-renewable resource, has significant potential to reduce GHG emissions. The approach to biomass, as the only true full-scale alternative to fossil resources, is progressing rapidly. Converting biomass into furanic compounds, as versatile platform chemicals for synthesizing a wide range of bio-based products is the cornerstone of sustainable technologies. The extensive body of this review combines the biomass valorization to furanic compounds by CO₂ utilization and furanic compounds conversion by CO₂ fixation. These processes can be strategically applied through both 'thermochemical' and 'electrochemical' pathways, by utilizing CO₂ from the atmosphere or industrial emission point and returning it to the natural carbon cycle. In the thermochemical pathway CO₂ acts as a carbon source (carboxylation and polymerization) or active reaction assistant in the biomass conversion (CO₂-assisted conversion), without altering its oxidation state, facilitating the synthesis of valuable products and polymers. Conversely, in the electrochemical pathway, CO₂ can be used as a carbon source (electrocarboxylation) to give the corresponding carboxylic acid, or it can undergo reduction, yielding methanol, carbon monoxide (CO), formic acid, and analogous compounds, while on the other side, furanic compounds undergo oxidation yielding high-value-added chemicals. Finally, potential future research directions are suggested to promote CO₂ utilization and fixation in the valorization of biomass-derived furanic compounds, and challenges facing further research are highlighted.