Metal organic framework-derived nitrogen-doped porous carbon sustained Prussian blue analogues for efficient and fast hybrid capacitive deionization

Prussian blue analogues (PBAs) are considered as exceptionally promising faradic electrode materials for next-generation capacitive deionization (CDI) electrodes due to their superior theoretical specific capacity, non-toxic property and simple preparation. However, the desalination performances of PBAs are hampered by their sluggish intrinsic kinetics and insufficient utilization of active sites. Herein, we demonstrate an advanced hybrid material constructed by anchoring nickel hexacyanoferrate (Ni-PBA) onto three-dimensional (3D) nitrogen-doped porous carbon (ZC) derived from zinc-based metal–organic frameworks (MOFs, ZIF-8) polyhedron. ZC with a 3D open structure not only provides multiple spatial supports for the in-situ growth of Ni-PBA with extraordinary redox capacity, but also features high electrical conductivity, excellent hydrophilicity and large surface area to facilitate the electron/ion transport and improve the ion accommodation. Therefore, the Ni-PBA/ZC composite electrode achieves an outstanding CDI desalination performance with an ultrahigh salt adsorption capacity (SAC) of 43.9 mg g−1 and maximum salt adsorption rate (mSAR) of 20.82 mg g−1 min−1, outperforming those of most of the recently reported MOF-derived porous carbon materials and PBAs-based materials. The strategy in this work presents a novel avenue by combining the advantages of MOF-derived porous carbon and redox-active materials for designing high-performance CDI electrode materials.