Improving Carbon Dioxide Conversion Efficiency through Immobilization of Formate Dehydrogenase PbFDH and Its Mutant D533S/E684I on Nanostructured Carriers

Abstract

Converting excess CO₂ in the atmosphere to value-added chemicals is a crucial strategy for mitigating the impact of carbon emissions on the global climate. Bioelectrocatalysis for the conversion of CO₂ to formic acid emerges as a promising technology; however, the limited stability of the enzyme restricts its practical application. In this study, two carriers (NU-1000 and HOF-101) were utilized to immobilize formate dehydrogenase (PbFDH and mutant D533S/E684I). Comparative analysis revealed that the temperature, pH, and storage stability of the immobilized enzyme were superior to those of the free enzyme. The residual activity of the immobilized enzyme retained approximately 80% after 30 days of storage. The bioelectrocatalysis system was established to convert CO₂ into formic acid, which facilitated the regeneration of NADH. The yield of formic acid produced using the D533S/E684I@HOF-101 electrode reached 10.4 mM/h. The formic acid production using the immobilized FDH was approximately twice that of the corresponding free enzyme after 10 h. The formic acid production capacity of immobilized enzyme electrodes remained at almost 85% after 10 cycles of reactions. This study offers an effective solution for the efficient conversion of CO₂ to formic acid and presents novel insights into enzyme immobilization.