Defect free rolling phase inversion activated carbon air cathodes for scale-up electrochemical applications

Scalable production of air cathodes is crucial for applying electrochemical technologies in practical water treatment applications. However, existing fabrication procedures of air cathodes for microbial fuel cells (MFCs) are either complicated or not sufficiently waterproof for larger-scale processes. In this study, an easily implemented low-pressure rolling phase inversion method was developed for preparing scalable, waterproof activated carbon air cathodes. An aminated PVDF (NH₂-PVDF) membrane was synthesized as a new gas diffusion layer (GDL) to avoid defect formation from contacting organic solvent during cathode fabrication. The cathode was easily enlarged to 1000 cm² with a high pressure resistance of 13 ± 0.7 m H₂O height (∼137 kPa), exceeding the waterproof capability of previously reported air cathodes. The electrochemical performance of the fabricated air cathode was not affected by the additional membrane. MFCs with the NH₂-PVDF cathodes produced a maximum power density of 1010 ± 40 mW m⁻², consistent with literature values. The cathode was used to generate H₂O₂ at a rate of 420 ± 40 mg L⁻¹ h⁻¹ (25 mA cm⁻²), and nickel catalyst modification further increased the rate to 760 ± 60 mg L⁻¹ h⁻¹ (25 mA cm⁻²). Overall, the highly waterproof rolling phase inversion activated carbon air cathodes showed great promise for scaling up biotic and abiotic electrochemical systems for practical applications.