HCl-activated porous nitrogen-doped carbon nanopolyhedras with abundant hierarchical pores for ultrafast desalination

Abstract

Exploring an emerging carbon-based material with optimized structure and controlled porosity is of significance for further heightening the capacitive deionization (CDI) performance and solving the problem of emergency fresh water supply. Herein, a porous nitrogen-doped carbon nanopolyhedra with hierarchical pores prepared via using zeolite-type metal-organic framework (ZIF-8) as precursor is reported and used for CDI. In order to prepare the nanomaterials with abundant hierarchical pore structure, the synthetic route of carbonization followed by HCl-activation is adopted. The resulting nitrogen-doped carbon materials exhibit a bimodal porosity containing micro- and meso-pores, high specific surface area, and numerous exposed adsorption active sites. The excellent performance in structure ensures the ultrahigh desalination capacity of 37.52 mg g−1 and excellent recyclability (retained 90% over 30 cycles) of the as-prepared carbon electrode material. Notably, the above electrode demonstrates ultrafast desalination rate of 16.01 mg g−1 min−1, which is 2–8 times faster than the conventional carbon materials. This present work may provide a new insight for developing efficient MOF-derived CDI electrode materials and realizing rapid water resource supply in emergencies such as outdoor survival or unexpected natural disasters.