Membraneless Microfluidic Microbial Electrolysis Cell with a Biocathode for Cost-Effective Hydrogen Production

In this study, an ecofriendly microfluidic microbial biocathode electrolysis cell is developed for hydrogen production. Low-cost microbial catalysts are employed on single-walled carbon nanotube cathodes instead of noble metal (platinum) catalysts. The channel layer for the electrolyte flow is fabricated from polydimethylsiloxane and coated with Parylene C to minimize oxygen permeability. A miniaturized electrolysis cell is constructed by depositing electrodes onto a glass substrate and bonding them to a polydimethylsiloxane channel layer via plasma surface treatment. The establishment of the biocathode during the start-up procedure is analyzed, and the hydrogen production performance of the biocathode microbial electrolysis cell (MEC) is evaluated under various applied voltages and electrolyte flow rates. At higher applied voltages and optimal flow rates, biofilm formation is well-developed, resulting in a peak hydrogen production rate of 14.8 m3 H2 m−3 d−1. The developed MEC biocathode demonstrates significant performance, achieving a current density of 0.22 A m−2, corresponding to 69% of that of a platinum-catalyzed cathode MEC, while exhibiting a substantially longer operating duration of 12 h. These results demonstrate the potential to overcome the inherent limitations of biocathodes, thereby addressing the high cost and low durability of conventional platinum-catalyzed MECs. Compared with conventional MEC systems, the proposed microfluidic configuration enables membraneless operation with reduced internal resistance and rapid biofilm formation, demonstrating its potential as a compact and cost-effective platform for biohydrogen production.