In situ disinfection and green hydrogen production using carbon-based cathodes in seawater electrolysis

Electrolysis is an advanced oxidation process used to treat aquaculture effluents, commonly by employing precious-metal-based electrodes. However, such electrodes increase operation costs, prompting the need for novel electrodes. Low-cost carbon-based electrodes have been suggested as large-surface-area electrodes; however, their stability under long-term electrochemical operation, particularly in natural seawater, should be improved. Herein, carbon-based cathodes were applied in seawater electrolysis for in situ disinfection and green hydrogen production to recycle aquaculture effluents. Functionalized carbon black (CB) generated the highest hydrogen production of 46.6 ± 4 mL (purity ≥99.9 ± 0.05 %), which was 1.4 times higher than that for bare carbon cloth (CC). The production of sodium hypochlorous acid at >600 ± 50 mg/L was higher over functionalized CB/CC than that over bare CC. Within 1 min, the aquaculture effluent was disinfected with a high removal efficiency of 99.5 ± 0.05 %, which was similar to that for a platinum/titanium cathode. The cathodes exhibited higher potential stability (3.7 ± 0.5 V) than platinum/CB/CC under a constant current for 20 h owing to the control of inorganic fouling. Thus, these electrodes are efficient alternatives that can promote commercialization by reducing the costs and facilitate electrochemical and green production of hydrogen and oxidants.