MR-1 respires CdSe quantum dots for photocatalytic hydrogen evolution.

Living bio-nano systems for artificial photosynthesis are of growing interest. Typically, these systems use photoinduced charge transfer to provide electrons for microbial metabolic processes, yielding a biosynthetic solar fuel. Here, we demonstrate an entirely different approach to constructing a living bio-nano system, in which electrogenic bacteria respire semiconductor nanoparticles to support nanoparticle photocatalysis. Semiconductor nanocrystals are highly active and robust photocatalysts for hydrogen (H) evolution, but their use is hindered by the oxidative side of the reaction. In this system, MR-1 provides electrons to a CdSe nanocrystalline photocatalyst, enabling visible light-driven H production. Unlike microbial electrolysis cells, this system requires no external potential. Illuminating this system at 530 nm yields continuous H generation for 168 h, which can be lengthened further by replenishing bacterial nutrients.