Decoupled Artificial Photosynthesis via a Catalysis-Redox Coupled COF||BiVO₄ Photoelectrochemical Device

Artificial photosynthesis is an attractive approach to direct fuel production from sunlight. However, the simultaneous O₂ evolution reaction (OER) and CO₂ reduction reaction (CDRR) present challenges for product separation and safety. Herein, we propose a strategy to temporally decouple artificial photosynthesis through photoelectrochemical energy storage. We utilized a covalent organic framework (DTCo-COF) with redox-active electron donors (-C-OH moieties) and catalytically active electron acceptors (cobalt-porphyrin) to enable reversible -C-OH/-C═O redox reaction and redox-promoted CO₂-to-CO photoreduction. Integrating the COF photocathode with an OER photoanode in a photoelectrochemical device allows the effective storage of OER-generated electrons and protons by -C═O groups. These stored charges can be later employed for CDRR while regenerating -C═O to complete the loop, thus enabling on-demand and separate production of O₂ or solar fuels. Our work sets the stage for advancements in decoupled artificial photosynthesis and the development of more efficient solar fuel production technologies.