Fig. 1. Schematic illustrations of PCF preparation and capacitive deionization.

(A) Synthesis of PCF from PMMA-b-PAN via electrospinning of PMMA-b-PAN into fibers, self-assembly of PMMA-b-PAN into disordered, bicontinuous PMMA and PAN domains, and pyrolysis of PMMA-b-PAN into PCF with uniform and interconnected pores in a continuous carbon matrix. PMMA generates mesopores and PAN yields carbon. Micropores are also generated in the carbon matrix during the pyrolysis of PAN and are interconnected with the mesopores. (B) Scheme of a CDI cell during charging. The CDI electrodes include (i) block copolymer–based PCF, (ii) conventional nonmesoporous CFs, and (iii) AC. (i versus ii) Compared to PAN-derived conventional CFs that are devoid of uniform mesopores, PCF has abundant interconnected mesopores that provide large ion-accessible surface areas and fast ion diffusion. Thus, PCF has a high desalination capacity and high desalination rate. (i versus iii) Compared to AC composed of discrete carbon particles with irregular shapes and sizes, PCF offers continuous electron and ion conduction pathways both in the vertical and in-plane directions that facilitate high-rate deionization.