A coupled photocatalytic/enzymatic system for sustainable conversion of CO₂ to formate

Enzymatic conversion of CO₂ into high-added chemicals is advantageous in mild reaction conditions and high specificity, for which enzyme immobilization and cofactor regeneration are often necessary. Although many efforts have been made, unfortunately, the turnover number (TN) of cofactor does not exceed 100 (~1 usually). Here, an integrated process of formate synthesis from CO₂ catalyzed by hollow fiber membrane immobilized enzyme succeeded with a simple UV/TiO₂ photocatalytic coenzyme regeneration was explored. By optimizing the operating conditions and NADH concentration, TN reached 125 after 4.5 h. This process can be extended to the production of methanol and other similar systems.