Coupling Photocatalytic Reduction and Biosynthesis Towards Sustainable CO₂ Upcycling

Upcycling carbon dioxide (CO₂) into long-chain compounds has attracted considerable attention with respect to mitigating environmental problems and obtaining value-added feedstocks, but remains a great challenge. Herein, we report a tandem photocatalysis-biosynthesis strategy for efficient CO₂ reduction to energy-rich sucrose or α-farnesene. Firstly, photocatalytic reduction of CO₂ to CH₄ was optimized over the transitional metal doped ZnO (M-ZnO). The as-prepared Ni-ZnO preferentially reduces CO₂ to CH₄ with a production rate of 1539.1 μmol g^-1 h^-1 and a selectivity of 90 %, owing to the unique interface structure (Zn^δ+-O-Ni^β+). Subsequently, Methylomicrobium buryatense 5GB1C was genetically engineered to produce sucrose or α-farnesene using photocatalytically-obtained CH₄ as the sole carbon source, with a titer of 96.3 and 43.9 mg L^-1, respectively. This study provides a green, low-energy pathway for the synthesis of long-chain compounds from CO₂ as the carbon source, which sheds new light on tackling long-term energy demands and sustainable CO₂ upcycling.