Polymer Photocatalyst–Enzyme Coupled Artificial Photosynthesis System for CO2 Reduction into Formate Using Water as the Electron Donor

Photocatalyst–biocatalyst coupled systems offer a sustainable approach for converting CO2 into high-value compounds. However, the usually excessive use of organic sacrificial electron donors often leads to undesired side products and toxic intermediates. Here, we report a complete artificial photosynthesis system for selective CO2 reduction into formate with simultaneous H2O2 formation using water as the electron donor. The photocatalyst consists of polymeric carbon nitride with implanted single cobalt atoms as oxidative sites, while formate dehydrogenase from Candida boidinii was employed as reductive sites via a coupled redox cycle of nicotinamide adenine dinucleotide as cofactor. The artificial photosynthesis system demonstrates a competitive catalytic formate production rate of 420 μmol gcat.–1 h–1. DFT calculations reveal that the presence of single cobalt atoms can significantly accelerate the water oxidation into H2O2. The result demonstrates a benchmark example of a polymeric artificial photosynthesis system with remarkable photostability and catalytic selectivity for high-value compound production directly from CO2 without using extra organic electron donors.