Microbial battery powered enzymatic electrosynthesis for carbon capture and generation of hydrogen and formate from dilute organics

A microbial battery (MB) breaks down waste organics and stores the liberated electrons in a solid-state cathode. Here, we demonstrate that these electrons can be utilized, along with the products (e.g., carbon dioxide, CO2) of the MB, to electrochemically generate higher value products from waste. We utilize a series-stacked MB with mediated enzymatic electrosynthesis (EES) to produce either hydrogen (H2) from protons (H+), or formate (HCOO-) from CO2 with the electrons and carbon directly derived from waste organics. We also demonstrate that a reduced solid-state cathode can be used as a solid-state anode as an electron source for EES. This work shows that higher value products can be electrochemically generated at high faradaic efficiencies (up to 91% for hydrogenase and 72% for formate dehydrogenase) using the energy, electrons, and carbon contained in the waste organic input without the need of continuous oxygen, potentiostatic control, or supplemental power.