Hollow ZIFs-derived nanoporous carbon for efficient capacitive deionization

Desalination performance of capacitive deionization (CDI), a promising deionization technology, depends significantly upon the compositions and internal structures of electrode materials . Herein, hollow ZIFs-derived nanoporous carbons (HZCs) were prepared via chemical etching method and subsequent pyrolysis . Particularly, the tannic acid as an etching agent was employed to tailor hollow structure. The resultant HZCs possess high surface area, wide pore size distribution , obvious hollow cavity and high nitrogen content. Moreover, HZCs electrodes exhibited a significantly improved CDI performance over the solid ZIFs-derived nanoporous carbons (SZCs) electrodes. The improved electrosorption rate and capacity (15.31 mg g -1  at 1.2 V) of HZCs electrode imply that hollow structure facilitates the transportation for both ions and mass on CDI process. Besides, the further cycle experiment exhibits a great regeneration stability of HZCs electrode over 20 adsorption-desorption cycles. All these results indicate that HZCs should be a promising candidate for CDI application.