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 for continuous oxygen, potentiostatic control, or supplemental power.