Enzymatic conversion of CO₂ to formate was carried out in the cathodic cell of a two-chamber electrochemical apparatus where NAD⁺ was reduced on the surface of a Copper foam electrode. Formate dehydrogenase (FDH) was used as the biocatalyst in both free form and immobilized on the modified electrospun polystyrene nanofibers (EPSNF). The fabricated EPSNF were modified by a multistage procedure including acid treatment, silanization followed by activation with glutaraldehyde. The effects of regenerated NADH concentration and time of enzymatic reaction on the formate production in the both systems were studied. The results indicated that the EPSNF immobilized FDH had a desirable activity, long-term storage stability (41% after 20 days) and reusability after eight cycles of successive reactions (53% of the initial activity). Moreover, it was revealed that the increase of cofactor concentration at the early times of reaction was favorable to the formate production. However, an inhibitory effect was observed at higher concentrations of NADH, and the optimum values of 0.45 mM and 0.51 mM were obtained for the maximum enzyme activity by the free and immobilized enzymes respectively. The produced formate at the optimum cofactor concentration after 300 min was 0.61 mM and 0.31 mM for the free and immobilized enzyme systems. Finally, it can be concluded that the presented process is a promising approach to the enzymatic conversion of CO₂.

在NAD ⁺的两腔电化学装置的阴极电池中，将CO ₂酶转化为甲酸。在泡沫铜电极的表面上被还原。甲酸酯脱氢酶（FDH）以游离形式用作生物催化剂，并固定在改性的电纺聚苯乙烯纳米纤维（EPSNF）上。通过包括酸处理，硅烷化，然后用戊二醛活化的多步程序对制备的EPSNF进行了改性。研究了两种系统中再生NADH浓度和酶促反应时间对甲酸盐产量的影响。结果表明，固定有EPSNF的FDH具有理想的活性，长期储存稳定性（20天后为41％）和八次连续反应循环后的可重复使用性（初始活性的53％）。此外，揭示了反应早期辅因子浓度的增加有利于甲酸盐的产生。然而，在较高浓度的NADH中观察到了抑制作用，游离酶和固定化酶的最大酶活性分别为0.45 mM和0.51 mM的最佳值。对于游离酶和固定化酶系统，在300分钟后最佳辅因子浓度下生成的甲酸盐分别为0.61 mM和0.31 mM。最后，可以得出结论，提出的方法是CO酶促转化的一种有前途的方法₂。