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Nano Research

Article Title

Holey graphene hydrogel with in-plane pores for high-performance capacitive desalination

Keywords

capacitive deionization, desalination, electrochemical capacitor, graphene hydrogel (GH), in-plane pore

Abstract

Capacitive deionization is an attractive approach to water desalination andtreatment. To achieve efficient capacitative desalination, rationally designedelectrodes with high specific capacitances, conductivities, and stabilities arenecessary. Here we report the construction of a three-dimensional (3D) holeygraphene hydrogel (HGH). This material contains abundant in-plane pores,offering efficient ion transport pathways. Furthermore, it forms a highlyinterconnected network of graphene sheets, providing efficient electron transportpathways, and its 3D hierarchical porous structure can provide a large specificsurface area for the adsorption and storage of ions. Consequently, HGH servesas a binder-free electrode material with excellent electrical conductivity. Cyclicvoltammetry (CV) measurements indicate that the optimized HGH can achievespecific capacitances of 358.4 F·g−1 in 6 M KOH solution and 148 F·g−1 in 0.5 MNaCl solution. Because of these high capacitances, HGH has a desalinationcapacity as high as 26.8 mg·g−1 (applied potential: 1.2 V; initial NaCl concentration:~5,000 mg·L−1).1 IntroductionWater scarcity is a serious global problem [1, 2].Although global water supplies exceed 1.38 billion km3,freshwater comprises only 2.5% of this. Furthermore,less than 1.2% of total freshwater is available for humanneeds because a significant proportion is inaccessible,locked away as ice and underground water [3]. Thedemand for freshwater will increase with populationgrowth, industrial development, and increasingcontamination [4]. Consequently, seawater desalinationis a technique of importance and long-standinginterest.Current desalination methods, such as thermalevaporation and membrane-based techniques, arelimited by the high costs of energy, initial investment,and maintenance; in addition, membrane fouling isa significant problem [5−7]. Recently, capacitiveNano ResearchDOI 10.1007/s12274-016-1132-8Address correspondence to Jiawen Hu, jwhu@hnu.edu.cn; Xiangfeng Duan, xduan@chem.ucla.edu

Graphical Abstract

Publisher

Tsinghua University Press

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