A two-pronged strategy to boost the capacitive deionization performance of nitrogen-doped porous carbon nanofiber membranes

• Published in: Desalination Vol. 594; p. 118293
• Main Authors: Ma, Xiang, Wang, Jian, Zhu, Zhaoyuan, Wang, Ning, Wang, Ce, Nie, Guangdi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 28.01.2025
• Subjects: Capacitive deionization; Electrospinning; Flexible membranes; Porous carbon nanofibers; ZIF-L; ZIF-L; Electrospinning; Capacitive deionization; Flexible membranes; Porous carbon nanofibers
• ISSN: 0011-9164
• DOI: 10.1016/j.desal.2024.118293

Carbon-based capacitive deionization (CDI) systems are universally subject to the limited desalination capacity, due to the electrosorption characteristics and undesirable pore structures. Herein, a two-pronged strategy is proposed to boost the desalination performance of the electrospun carbon nanofibers (CNFs), where silicalite-1 nanoparticles as the internal porogen create mesopores and macropores, and layered zeolitic imidazolate framework (ZIF-L) leaves as the external carbon source provide micropores and mesopores. This combination results in the large surface area, well-developed graded pore structure, and increased nitrogen content of the core-shell polyacrylonitrile/silicalite-1@ZIF-L-derived CNFs (defined as PCNFs-SZ) electrode, which delivers a superior specific capacitance of 145.4 F g−1 in a neutral electrolyte. The symmetric CDI cell assembled by the self-supporting PCNFs-SZ membrane electrodes holds a prominent desalination capacity of 37.09 mg g−1 and a rapid salt removal rate of 10.36 mg g−1 min−1 at 1.2 V (initial NaCl concentration: 500 mg L−1), and demonstrates significant potential for real-world applications in the desalination and purification of reclaimed water. Furthermore, theory calculations confirm the enhanced Na+-capture capability of PCNFs-SZ. The present work highlights an effective and viable approach to enhance the desalination performance of carbon-based CDI cells. [Display omitted] •A two-pronged strategy is proposed to boost the CDI performance of CNFs.•Silicalite-1 and ZIF-L leaves act as the internal porogen and the external carbon source.•The PCNFs-SZ show well-developed pore structures and an increased nitrogen content.•DFT calculations confirm the enhanced Na+-capture capability of PCNFs-SZ.•The CDI cell based on PCNFs-SZ delivers superior capacitive desalination capacity.