Strategies for overcoming the limitations of enzymatic carbon dioxide reduction.

The overexploitation of fossil fuels has led to a significant increase in atmospheric carbon dioxide (CO) concentrations, thereby causing problems, such as the greenhouse effect. Rapid global climate change has caused researchers to focus on utilizing CO in a green and efficient manner. One of the ways to achieve this is by converting CO into valuable chemicals via chemical, photochemical, electrochemical, or enzymatic methods. Among these, the enzymatic method is advantageous because of its high specificity and selectivity as well as the mild reaction conditions required. The reduction of CO to formate, formaldehyde, and methanol using formate dehydrogenase (FDH), formaldehyde dehydrogenase (FDH), and alcohol dehydrogenase (ADH) are attractive routes, respectively. In this review, strategies for overcoming the common limitations of enzymatic CO reduction are discussed. First, we present a brief background on the importance of minimizing of CO emissions and introduce the three bottlenecks limiting enzymatic CO reduction. Thereafter, we explore the different strategies for enzyme immobilization on various support materials. To solve the problem of cofactor consumption, different state-of-the-art cofactor regeneration strategies as well as research on the development of cofactor substitutes and cofactor-free systems are extensively discussed. Moreover, aiming at improving CO solubility, biological, physical, and engineering measures are reviewed. Finally, conclusions and future perspectives are presented.