Light-driven biohybrid system utilizes N 2 for photochemical CO 2 reduction.

Attempting to couple photochemical CO 2 reduction with N 2 fixation is usually difficult, because the reaction conditions for these two processes are typically incompatible. Here, we report that a light-driven biohybrid system can utilize abundant, atmospheric N 2 to produce electron donors via biological nitrogen fixation, to achieve effective photochemical CO 2 reduction. This biohybrid system is constructed by incorporating molecular cobalt-based photocatalysts into N 2 -fixing bacteria. It is found that N 2 -fixing bacteria can convert N 2 into reductive organic nitrogen and create a localized anaerobic environment, which allows the incorporated photocatalysts to continuously perform photocatalytic CO 2 reduction under aerobic conditions. Specifically, the light-driven biohybrid system displays a high formic acid production rate of over 1.41 × 10 -14  mol h -1 cell -1 under visible light irradiation, and the organic nitrogen content undergoes an over-3-fold increase within 48 hours. This work offers a useful strategy for coupling CO 2 conversion with N 2 fixation under mild and environmentally benign conditions.