Mesopore-enhanced graphene electrodes with modified hydrophilicity for ultrahigh capacitive deionization

Capacitive deionization (CDI) technology represents a potent approach towards energy-efficient and sustainable access to potable water, with minimal environmental impact. However, the ion removal capacity of CDI systems remains inadequate for desalination of saline water. Herein, mesopore-enhanced graphene foam with modified hydrophilicity via O2-plasma treatment (MGFP) is proposed for ultrahigh CDI. This developed MGFP encompasses abundant mesopores, outstanding electrical conductivity and good hydrophilicity, enabling fast ions migration, efficient solution/pores contact and high adsorption capacity. As such, MGEP delivers a high specific capacitance of 156.64 F g−1 at 1 mV s−1, and a maximum salt adsorption capacity (SAC) up to 40.76 mg g−1 (1000 mg L−1, 1.2 V), much higher than most of the CDI systems leveraging the carbon-based materials. What's more, MGFP can be employed in the treatment of wastewaters containing various heavy metals, with the SAC of 89.96, 83.38, and 91.80 mg g−1, as for CuCl2, CoCl2, and NiCl2 (1000 mg L−1, 1.6 V), respectively. This well-developed MGFP undoubtedly presents a promising material platform within the CDI system, effectively tackling the pressing concern of water scarcity.