Ag-doped hollow ZIFs-derived nanoporous carbon for efficient hybrid capacitive deionization

Desalination performance of hybrid capacitive deionization (HCDI) intensively depends on the electrode materials with redox activity and capacitance ability. Herein, Ag-doped hollow ZIFs-derived nanoporous carbon (Ag/ZCs) was employed as an anode material by the pyrolysis of Ag-doped hollow ZIFs precursor, which was fabricated by in situ tannic acid (TA) etching/reduction strategy. Provably, TA serves as not only an etchant for tailoring ZIFs structure, but also a reductant for Ag nanoparticles formation. The obtained Ag/ZCs possesses unique hollow cavities and high redox activity. As expected, the HCDI system with Ag/ZCs electrode exhibits excellent deionization capacity of 29.18 mg g −1 in 500 mg L −1 NaCl solution at 1.2 V, which is much higher than that of conventional carbon-based CDI system. Moreover, desirable regeneration stability of the Ag/ZCs HCDI was well maintained after 20 cycle experiments. The results demonstrate that Ag/ZCs is a potential anode material for HCDI applications.