Abstract
As water shortage has become a serious global problem, capacitive deionization (CDI) with high energy efficiency and low cost, is considered as a promising desalination technique to solve this problem. To date, CDI electrodes are mainly made up of porous carbon materials. However, the electrosorption performance obtained by now still cannot meet the demand of practical application. Therefore, a rationally designed structure of electrode materials has been an urgent need for CDI application. Here, a novel nitrogen-doped graphene sponge (NGS), with high specific surface area and rationally designed structure was fabricated, and used as CDI electrodes for the first time. The results show that NGS exhibits an ultrahigh electrosorption capacity of 21.0 mg g−1 in ∼500 mg L−1 NaCl solution, and to our knowledge, it is the highest value reported for carbon electrodes in similar experimental conditions by now. NGS in this work is expected to be a promising candidate as CDI electrode material.
Highlights
0.45–1.85 mg g−1,19–21 which hampers its application in capacitive deionization (CDI)
There is no change in the specific capacitance of nitrogen doped graphene sponge (NGS) after 1000 cycles, and its cyclic voltammetry (CV) curve keeps the original shape. These results indicate that our NGS is expected to become a superb CDI electrode material, and a promising candidate as supercapacitor electrode materials
NGS should be a promising candidate as CDI electrode material for practical applications
Summary
0.45–1.85 mg g−1,19–21 which hampers its application in CDI. To date, two strategies have been applied to prevent the agglomeration between graphene nanosheets, and enhance their CDI performance. Efforts are made to design and optimize the structure of graphene for its practical application in CDI. Towards this aim, three-dimensional (3D) graphene structures including 3D macroporous graphene architectures29, 3D graphene-based hierarchically porous carbon composites[30], sponge-templated prepared graphene31, 3D graphene/metal oxide hybrids[32] and our recently reported graphene sponge (GS)[33] have been fabricated and used as CDI electrodes. Essential efforts are still needed to seek a facile and low-cost strategy to fabricate novel graphene structure with high electrosorption capacity for practical applications of CDI. When used as CDI electrodes, the obtained NGS exhibits an ultrahigh electrosorption capacity of 21.0 mg g−1 in NaCl solution with an initial concentration of ∼ 500 mg L−1, which is much higher than those of other carbon based electrodes in similar experimental conditions reported in the literatures
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