Boosting the photocatalytic CO2 conversion efficiency of MOFs using a solid electron conveyor

Abstract

Inspired by the natural photosynthesis, various artificial hybrid bio-coupled photocatalytic systems have been developed with encouraging achievements. However, the catalytic efficiency is impeded by the sluggish electron transfer kinetics from the photosensitizer to enzymes. Herein, we establish a semiartificial photosynthesis system where a solid electron hyper-channel to cavity confined enzymes was constructed by connecting 1-(carboxynonyl)-1′-methyl-[4,4′-bipyridine]-1,1′-diium (CNMV) with the photosensitizer through Zr₆ nodes in a MOF. The oriented solid electron conveyor enables ultrafast photogenerated electron transfer from the photosensitizer to the MOF encapsulated formate dehydrogenase (FDH) through authenticated multistep redox pairs. The conformation of FDH is altered to one with an open active site cleft induced by the framework–enzyme interaction. Utilizing these attributions, the photocatalytic CO₂ reduction rate reached 1.17 μmol h⁻¹ per unit of enzyme and the reaction kinetics of this system was enhanced 190-fold compared with that using the classic nicotinamide adenine dinucleotide (NADH) as the coenzyme.