Light-driven biohybrid system utilizes N2for photochemical CO2 reduction

Abstract

Attempting to couple photochemical CO2 reduction with N2 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 N2 to produce electron donors via biological nitrogen fixation, to achieve effective photochemical CO2 reduction. This biohybrid system is constructed by incorporating molecular cobalt-based photocatalysts into N2-fixing bacteria. It is found that N2-fixing bacteria can convert N2 into reductive organic nitrogen and create a localized anaerobic environment, which allows the incorporated photocatalysts to continuously perform photocatalytic CO2 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 CO2 conversion with N2 fixation under mild and environmentally benign conditions.