Hierarchically porous metal organic framework immobilized formate dehydrogenase for enzyme electrocatalytic CO2 reduction

The utilization of CO 2 has become an important issue aiming to the achievement of carbon neutrality. The enzyme electrocatalytic CO 2 reduction to produce carbonaceous fuels has been increasingly appealing. While the low CO 2 aqueous solubility severely limits the CO 2 reduction efficiency, and the expensive cofactor restricts the application potential. In this study, microporous UiO-66-NH 2 was firstly converted into hierarchically porous structure (HP-UiO-66-NH 2 ) containing both micropores and mesopores to simultaneously enhance the enrichment of CO 2 and the immobilization of formate dehydrogenase by optimizing the pore structure. The relative contents of the protein secondary structures were similar after immobilization. The mechanism of enzyme electrocatalytic CO 2 reduction was proposed. The enzyme stability was highly enhanced after immobilization and the CO 2 reduction was enhanced by the enzyme electrocatalytic system through the combination of CO 2 enrichment and electrocatalytic NADH regeneration. The optimized catalytic system can obtain formate yield of 1.826 mM in 3 h (5.57 times higher than the free enzyme system) with a generation rate of 6086.7 μmol g cat ‑1 h ‑1 .