1D model simulations suggest biofilms can suppress cathodic H2 bubble formation

Cathodic biofilms in microbial electrosynthesis suppress H2 bubble formation by keeping cathode-surface H2 below saturation, enabling a 5.5-fold higher bubble-onset current density versus bare electrodes.

• Why it matters: The role of cathodic biofilms in MES is debated, and understanding how they affect H2 loss and bubble formation is key for improving CO2-to-acetate performance.
• What they did: The study built MES-BIOFILM, a one-dimensional steady-state model of H2 and CO2 gradients in cathodic biofilms, varying thickness, cell density, and H2 consumption rate while accounting for limited H2 solubility.
• The result: Simulations show H2 loss is minimized via biofilm H2 consumption and bubble formation is suppressed; bubble onset current density increases 5.5-fold with high cell density and high H2 consumption, requiring ≥50 m biofilm thickness and failing when CO2 diffusion limitations appear above 200 m.

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