Photoelectrocatalytic biosynthesis fueled by microplastics

Biocatalytic artificial photosynthesis integrates photocatalysis and redox biocatalysis through inspiration from plants to synthesize value-added chemicals using solar energy. The nature-inspired approach, however, suffers from sluggish rates due to the challenging water oxidation kinetics. Here, we report photoelectrochemical (PEC) biosynthetic reactions that use nonrecyclable real-world PET microplastics as an electron feedstock. A Zr-doped hematite photoanode (i) extracts electrons from hydrolyzed PET solutions obtained from post-consumer PET wastes (e.g., drinking bottles) and (ii) transfers the electrons to the bioelectrocatalytic site. Carbon-based cathodes receive the electrons to (i) activate redox enzymes [e.g., unspecific peroxygenase (UPO), L-glutamate dehydrogenase (GDH), ene-reductase from the old yellow enzyme family (OYE)] and (ii) drive various organic synthetic reactions, such as oxyfunctionalization of C-H bonds, amination of C=O bonds, and asymmetric hydrogenation of C=C bonds. These photoelectrocatalyst/biocatalyst hybrids achieve benchmark total turnover numbers of 362,000 (UPO), 144,000 (GDH), and 1,300 (OYE). This work presents a photoelectrocatalytic approach for integrating environmental remediation and biocatalytic photosynthesis towards sustainable solar-to-chemical synthesis.