Light-Driven CO Reduction with a Surface-Displayed Enzyme Cascade-CN Hybrid.

Efficient and cost-effective conversion of CO to biomass holds the potential to address the climate crisis. Light-driven CO conversion can be realized by combining inorganic semiconductors with enzymes or cells. However, designing enzyme cascades for converting CO to multicarbon compounds is challenging, and inorganic semiconductors often possess cytotoxicity. Therefore, there is a critical need for a straightforward semiconductor biohybrid system for CO conversion. Here, we used a visible-light-responsive and biocompatible CN porous nanosheet, decorated with formate dehydrogenase, formaldehyde dehydrogenase, and alcohol dehydrogenase to establish an enzyme-photocoupled catalytic system, which showed a remarkable CO-to-methanol conversion efficiency with an apparent quantum efficiency of 2.48% in the absence of externally added electron mediator. To further enable the in situ transformation of methanol into biomass, the enzymes were displayed on the surface of , which was further coupled with CN to create an organic semiconductor-enzyme-cell hybrid system. Methanol was produced through enzyme-photocoupled CO reduction, achieving a rate of 4.07 mg/(L·h), comparable with reported rates from photocatalytic systems employing mediators or photoelectrochemical cells. The produced methanol can subsequently be transported into the cell and converted into biomass. This work presents a sustainable, environmentally friendly, and cost-effective enzyme-photocoupled biocatalytic system for efficient solar-driven conversion of CO within a microbial cell.