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 (Znδ+-O-Niβ+). 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.