Hierarchically yolk-shell porous carbon sphere as an electrode material for high-performance capacitive deionization

The yolk-shell porous carbon spheres (YS-PCSs) with hierarchically nanoarchitecture were fabricated via a gradient sol-gel process combined with surfactant-directed co-assembly at different carbonized temperature of 600 °C, 700 °C, and 800 °C. The samples were used as electrode materials in capacitive deionization (CDI) process to measure their desalination performances. The results demonstrated that YS-PCS700 electrode displayed the best capacitive behavior and the lowest ions transfer resistance among all YS-PCS samples, and the electrosorption capacity reached up to 19.77 mg g−1 with 1.2 V applied voltage when the initial concentration of NaCl solution was 1000 mg L−1. The enhanced CDI performance was presumably attributed to the high specific surface area (1058 m2 g−1), the large pore volume (1.77 cm3 g−1) and the good wettability. Moreover, YS-PCS700 electrode still maintained excellent electrosorption capacity after 20 cycles CDI experiments under the same experimental conditions, indicating wonderful regeneration ability. It was desirable to develop the YS-PCS700 as a promising and alternative electrode material in CDI application.