Hybrid Electrophototroph Enables High-Efficiency Carbon Dioxide Valorization to Fuel Molecules

Abstract

Abstract Nature’s biocatalytic processes are driven by photosynthesis, whereby photosystems I and II are connected in series for light-stimulated generation of fuel products or electricity. Externally supplying electricity directly to the photosynthetic electron transfer chain (PETC) has numerous potential benefits, although strategies for achieving this goal have remained elusive. Here we report an integrated photo-electrochemical architecture which shuttles electrons directly to PETC in living cyanobacteria. The cathode of this architecture electrochemically interfaces with cyanobacterial cells lacking photosystem II activity that cannot perform photosynthesis independently. Illumination of the cathode channels electrons from external circuit to intracellular PETC through photosystem I, ultimately fueling CO2 conversion to acetate, a model fuel molecule with 9.32% energy efficiency, exceeding the efficiency of natural photosynthesis in higher plants (<1%) and cyanobacteria (~4-7%). The resulting “Electrophototrophic” bio-electrochemical hybrid has the potential to produce fuel chemicals with numerous advantages over standalone natural and artificial photosynthetic approaches.

Key findings

• ▸Electrophototrophic system achieves 9.32% energy efficiency in CO2 conversion to acetate, exceeding natural photosynthesis efficiency in higher plants and cyanobacteria.
• ▸System utilizes an integrated photo-electrochemical architecture that electrochemically interfaces with cyanobacterial cells lacking photosystem II activity.
• ▸Electrons are channeled from external circuit to intracellular PETC through photosystem I, fueling CO2 conversion to acetate.

Keywords

Identifiers

DOI

10.21203/rs.3.rs-93987/v1

Journal

Research Square (Research Square)

Year

2020