Xu Xingtao, Pan Likun, Liu Yong, Lu Ting, Sun Zhuo, Chua Daniel H C
Engineering Research Center for Nanophotonics &Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062, China.
Department of Materials Science and Engineering, National University of Singapore, Singapore 117574.
Sci Rep. 2015 Feb 13;5:8458. doi: 10.1038/srep08458.
Capacitive deionization (CDI) is an effective desalination technique offering an appropriate route to obtain clean water. In order to obtain excellent CDI performance, a rationally designed structure of electrode materials has been an urgent need for CDI application. In this work, a novel graphene sponge (GS) was proposed as CDI electrode for the first time. The GS was fabricated via directly freeze-drying graphene oxide solution followed by annealing in nitrogen atmosphere. The morphology, structure and electrochemical performance of GS were characterized by scanning electron microscopy, Raman spectroscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The electrosorption performance of GS in NaCl solution was studied and compared with pristine graphene (PG). The results show that due to the unique 3D interconnected porous structure, large accessible surface area and low charge transfer resistance, GS electrode exhibits an ultrahigh electrosorption capacity of 14.9 mg g(-1) when the initial NaCl concentration is ~500 mg L(-1), which is about 3.2 times of that of PG (4.64 mg g(-1)), and to our knowledge, it should be the highest value reported for graphene electrodes in similar experimental conditions by now. These results indicate that GS should be a promising candidate for CDI electrode.
电容去离子化（CDI）是一种有效的脱盐技术，为获取清洁水提供了一条合适的途径。为了获得优异的CDI性能，合理设计电极材料结构对于CDI应用而言已成为迫切需求。在本工作中，首次提出将新型石墨烯海绵（GS）用作CDI电极。通过直接对氧化石墨烯溶液进行冷冻干燥，随后在氮气气氛中退火来制备GS。采用扫描电子显微镜、拉曼光谱、氮气吸附-脱附、X射线光电子能谱、循环伏安法和电化学阻抗谱对GS的形貌、结构和电化学性能进行了表征。研究了GS在NaCl溶液中的电吸附性能，并与原始石墨烯（PG）进行了比较。结果表明，由于独特的三维互连多孔结构、大的可及表面积和低的电荷转移电阻，当初始NaCl浓度约为500 mg L(-1)时，GS电极表现出14.9 mg g(-1)的超高电吸附容量，约为PG（4.64 mg g(-1)）的3.2倍，据我们所知，这应该是目前在类似实验条件下石墨烯电极所报道的最高值。这些结果表明，GS应该是CDI电极的一个有前景的候选材料。
