Y. Ding, Yude Su
Semiartificial photosynthetic system (SAPS) combines the strengths of microbial enzyme machinery and semiconductor light harvesters, offering a promising platform to achieve solar-driven CO 2 conversion. However, existing CO 2 -fixing SAPSs are constrained by the limited choices of CO 2 -assimilating microorganisms, while the use of non-CO 2 -assimilating microbes in SAPS for solar-driven CO 2 conversion has rarely been demonstrated. In this work, we developed an integrated nanobiohybrid by co-introducing quantum dots (QDs) and molecular catalysts (MCs) into a non-CO 2 -assimilating bacterium, Azotobacter vinelandii ( A. vinelandii ), enabling a cascade photocatalytic reduction of CO 2 to C 2 H 4 via CO intermediates. The intracellular microanaerobic environment protects the QD-MC assembly from O 2 and promotes the photocatalytic CO 2 -to-CO conversion, while the intracellularly generated CO accelerates subsequent light-driven enzymatic synthesis of C 2 H 4 . The synergistic interactions among QD, MC, and bacteria were confirmed by fluorescent CO probing, time-resolved photoluminescence (TRPL), and in vitro control experiments. An optimized system achieved an accumulation of 7.9 μmol L –1 C 2 H 4 over 7 days without loss of activity, showing a yield of 2.1 × 10 7 C 2 H 4 per cell, surpassing the natural production by 162%. Our work introduced a novel integrated tandem biohybrid system that broadens the category of microbial organisms applied in CO 2 -fixing SAPS. We envision that this tandem biohybrid strategy can be extended to broader non-CO 2 -assimilating microbes for the production of other value-added chemicals beyond C 2 H 4 from CO 2 .