Feasibility of sulfur oxidizing bacteria-assisted electrolysis for low-voltage H2 evolution with autotrophic CO2 fixation

초록

A sulfur-oxidizing bacteria electrolysis cell (SOB-EC) employing Acidithiobacillus thiooxidans was systematically designed and experimentally evaluated for simultaneous sulfur oxidation, CO2 fixation, and hydrogen production. A. thiooxidans sustained growth and sulfur-oxidation across 0.1-5.0 % CO2 and 100 mM NaCl, demonstrating adaptability to CO2 elevated conditions and electrolyte conditions. CO2 assimilation into biomass confirmed the carbon sequestration potential of the system. Electrochemical analyses revealed reduced internal resistance, enhanced ion transport, and increased current density, enabling hydrogen evolution at voltages significantly lower than those required for conventional electrolysis. The open circuit voltage of SOB-EC increased to 485.4 +/- 15.6 mV. The SOB-EC achieved a theoretical H2 yield of 2.7-6.7 mmol.m-2.min-1 (0.4-0.6 V), corresponding to a theoretical energy consumption of 34.3 +/- 2.7 kWh.kg-1-H2 (0.6 V). This conceptually demonstrates the feasibility of coupling microbial sulfur oxidation with low-energy bioelectrochemical hydrogen generation in SOB-ECs, offering a novel route for renewable energy and greenhouse gas mitigation. Future studies should optimize extracellular electron-transfer pathways, reactor configuration, and operational parameters to translate this concept into practical, scalable SOB-EC systems for low-voltage bioassisted electrolysis applications with eco-friendly energies such as solar and wind power.

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