Electrocatalytic biomass upgrading coupled with hydrogen evolution and CO₂ reduction

Clean energy production and CO₂ utilization have attracted increasing interest. Electrocatalysis represents an effective way to produce green hydrogen from water and reduce CO₂ to valuable compounds. However, for either the hydrogen evolution reaction (HER) or the CO₂ reduction reaction (CO₂RR), the reaction efficiency is significantly limited by the slow kinetics of the oxygen evolution reaction (OER) at the anode, which consumes most of the input energy. Therefore, great efforts have been made to replace the OER with organic oxidation reactions at the anode to decrease the reaction energy barrier. Biomass has an advantage of broad source, and when it is employed as an OER alternative in the anode oxidation reactions, not only can the reduction reaction efficiency at the cathode including the HER and CO₂RR be enhanced but high-value chemicals can also be obtained, representing an attractive OER alternative. This review comprehensively summarizes the recent achievements in electrocatalytic biomass upgrading coupled with the HER and CO₂RR, cataloged based on the type of biomass. The design of electrocatalysts for such coupled reaction systems is discussed. Finally, the challenges and perspectives in the field of this energy-saving and value-added coupling system are provided to inspire more efforts in pushing forward the development of this field.