Exceptional capacitive deionization rate and capacity by block copolymer-based porous carbon fibers

Tianyu Liu; Joel Serrano; John Elliott; Xiaozhou Yang; William Cathcart; Zixuan Wang; Zhen He; Guoliang Liu

doi:10.1126/sciadv.aaz0906

Exceptional capacitive deionization rate and capacity by block copolymer-based porous carbon fibers

Sci Adv. 2020 Apr 17;6(16):eaaz0906. doi: 10.1126/sciadv.aaz0906. eCollection 2020 Apr.

Authors

Tianyu Liu¹, Joel Serrano¹, John Elliott¹, Xiaozhou Yang¹, William Cathcart¹, Zixuan Wang², Zhen He², Guoliang Liu^{1

3}

Affiliations

¹ Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA.
² Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061, USA.
³ Macromolecules Innovation Institute, and Division of Nanoscience, Virginia Tech, Blacksburg, VA 24061, USA.

Abstract

Capacitive deionization (CDI) is energetically favorable for desalinating low-salinity water. The bottlenecks of current carbon-based CDI materials are their limited desalination capacities and time-consuming cycles, caused by insufficient ion-accessible surfaces and retarded electron/ion transport. Here, we demonstrate porous carbon fibers (PCFs) derived from microphase-separated poly(methyl methacrylate)-block-polyacrylonitrile (PMMA-b-PAN) as an effective CDI material. PCF has abundant and uniform mesopores that are interconnected with micropores. This hierarchical porous structure renders PCF a large ion-accessible surface area and a high desalination capacity. In addition, the continuous carbon fibers and interconnected porous network enable fast electron/ion transport, and hence a high desalination rate. PCF shows desalination capacity of 30 mg_NaCl g^-1 _PCF and maximal time-average desalination rate of 38.0 mg_NaCl g^-1 _PCF min^-1, which are about 3 and 40 times, respectively, those of typical porous carbons. Our work underlines the promise of block copolymer-based PCF for mutually high-capacity and high-rate CDI.

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