MnO2 decorated porous carbon derived from Enteromorpha prolifera as flow-through electrode for dual-mode capacitive deionization

Abstract Owing to fresh-water shortage, developing highly efficient capacitive deionization (CDI) system equipped with low-cost electrodes is urgently required to process saline water to freshwater. On the other hand, Enteromorpha prolifera (EP for short, a typical bio-waste in global oceans) induced marine ecological crisis has become a serious threat to the global marine ecosystem. Aiming to kill two birds with one stone, we report the design of an EP-derived MnO2-decorated activated carbon composite (ep-AC@MnO2) as low-cost electrodes for high-performance dual-mode capacitive deionization. The as-fabricated ep-AC@MnO2 displays a high specific capacitance of 335.6 F g−1 with dual-mode sodium storage behavior. Benefiting from this unique dual-mode capacitance feature, the ep-AC@MnO2-based dual-mode CDI system exhibits highly efficient desalination performance (desalination capacity/rate: 25.7 mg g−1/2.95 mg g−1 min−1) with excellent desalination recyclability (11.3% declination after 30 cycles). This work could be of broad interest since it not only exemplifies the simple fabrication of low-cost yet high-efficiency CDI electrode material with dual-mode capacitance for capacitive desalination, but also offers a sustainable strategy to turn marine biowaste into treasure for possible relieving of the EP-induced marine ecological crisis.