Wave-driven core-shell structured cathode SMESs for remediation of phenanthrene and pyrene-contaminated offshore...

To address polycyclic aromatic hydrocarbon (PAHs) contamination in offshore sediment, a novel wave-energy-driven aluminum-copper core-shell structure cathode was developed for sedimentary microbial electrochemical systems (SMESs). The 6-cm diameter core-shell structure cathode assembly (CS-6cm) in this study optimized electron transfer pathways through contact electrification effects, enabling the system to maintain a stable output voltage of 480 mV (peak 650 mV) over 110 days, achieving removal rates of 54.4% for phenanthrene and 49.2% for pyrene. Compared to conventional carbon felt cathodes, it reduces costs by approximately 80% while delivering comparable performance. Furthermore, this study combined density functional theory (DFT) to elucidate the mechanism of differential degradation in phenanthrene: In open-circuit systems lacking electron pathways, nucleophilic substitution occurs at the side-chain methyl, followed by degradation via the naphthalene pathway. Under closed-circuit conditions, the π-electron delocalization in the anthracene conjugated system is enhanced by electron transfer, causing the hydroxyl group (-OH) to preferentially attack the intermediate ring to initiate degradation, which subsequently proceeds via the Biphenyl pathway, which has lower energy and lower toxicity, highlighting the advantages of anthracene degradation under electrochemical stimulation. In summary, this study integrates marine energy utilization with in situ remediation, advancing the application of economical, green, and efficient SMESs in offshore sediment remediation.