Elevating the stability of nanowire electrodes by thin polydopamine coating for low-voltage electroporation-disinfection of pathogens in water

Highly efficient, low-energy-consuming, reliable, and easily-applicable disinfection methods are in great demand for protecting human health from waterborne diseases. Nanowire-assisted low-voltage electroporation enables effective and energy-efficient disinfection. Nevertheless, the insufficient stability of the nanowires has become the main obstacle in practical applications: the commonly used copper-oxide-nanowire-modified copper foam (CuONW-Cu) electrode can only sustain the complete disinfection for about 10 min. Here, we improve the stability of the nanowires by applying a protective polydopamine (PDA) coating. The solution based self-polymerization approach produces a robust and uniform PDA layer with a controllable thickness of 0–100 nm. The PDA coating barely affects the effectiveness of the nanowires. With a 100 nm-thick PDA coating, CuONW-Cu electrodes still enable high disinfection performance. The electroporation disinfection cell (EDC) equipped with the PDA-coated CuONW-Cu electrodes achieves complete disinfection (>6.0 log) with a low applied voltage (1 V) and a high flux (1.8 m3 h−1 m−2; 20 s of contact time). Under such operation conditions, the EDC continuously treats water for 16 h while maintaining complete disinfection. The lifetime of the PDA-coated CuONW-Cu electrode is about 100-fold longer than that of the uncoated CuONW-Cu electrode. Besides, EDCs with PDA-CuONW-Cu electrodes also achieved high-efficiency disinfection for real and complex environmental systems (secondary effluents from the wastewater treatment plant).