Redox Molecular Junction Metal-Covalent Organic Frameworks for Light-assisted CO₂ Energy Storage

Visible-light sensitive and bi-functionally favored CO₂ reduction (CRR)/evolution (CER) photocathode catalysts that can get rid of the utilization of ultraviolet light and improve sluggish kinetics is demanded to conquer the current technique-barrier of traditional Li-CO₂ battery. Here, a kind of redox molecular junction sp²c metal-covalent organic framework (i.e. Cu₃-BTDE-COF) has been prepared through the connection between Cu₃ and BTDE and can serve as efficient photocathode catalyst in light-assisted Li-CO₂ battery. Cu₃-BTDE-COF with redox-ability, visible-light-adsorption region, electron-hole separation ability and endows the photocathode with excellent round-trip efficiency (95.2 %) and an ultralow voltage hysteresis (0.18 V), outperforming the Schiff base COFs (i.e. Cu₃-BTDA-COF and Cu₃-DT-COF) and majority of the reported photocathode catalysts. Combined theoretical calculations with characterizations, Cu₃-BTDE-COF with the integration of Cu₃ centers, thiazole and cyano groups possess strong CO₂ adsorption/activation and Li⁺ interaction/diffusion ability to boost the CRR/CER kinetics and related battery property.