Capacitive deionization (CDI) is one of the high-efficient technologies for desalination of brackish water. In this paper, a composite electrode with 3D CuNi foam (CNF) as current collector and reduced graphene oxide (rGO) as active material was synthesized, in which graphene oxide was reduced in situ and immobilized on the 3D CNF. Obtained rGO/CNF electrodes were directly employed as anode and cathode in a CDI cell. The effects of different substitution reaction time on the electrodes were investigated by SEM, XRD, Raman and XPS. Results showed that the existence of Cu on CNF could adjust the morphology and the defect content of rGO. The specific capacity of rGO/CNF-1.5 electrode (Note: 1.5 stands for the substitution reaction time) reached 352.5 F·g⁻¹ at 5 mV·s⁻¹ in 1.0 M NaCl electrolyte. During desalination, the rGO/CNF-1.5 electrode has a high salt adsorption capacity (SAC) of 84.6 mg/g in 250 mg/L NaCl solution at 1.2 V, which is 2.23 times higher than that of rGO/NF. The high performance of desalination can be attributed to the formation of electric double layer capacitance and pseudocapacitance. After 20 cycles, the SAC of rGO/CNF-1.5 electrode remains at 77.1 mg/g which is over 91 % of the original SAC.

电容去离子（CDI）是一种高效的微咸水淡化技术。在本文中，合成了一种以 3D Cu Ni 泡沫（CNF）为集流体和还原氧化石墨烯（rGO）为活性材料的复合电极，其中氧化石墨烯被原位还原并固定在 3D CNF 上。获得的 rGO/CNF 电极直接用作 CDI 电池的阳极和阴极。通过SEM、XRD、Raman和XPS研究了不同取代反应时间对电极的影响。结果表明，CNF上Cu的存在可以调节rGO的形貌和缺陷含量。rGO/CNF-1.5电极的比容量（注：1.5代表取代反应时间）在5 mV·s ^{-1时达到352.5 F·g -1}在 1.0 M NaCl 电解液中。在脱盐过程中，rGO/CNF-1.5 电极在 1.2 V 的 250 mg/L NaCl 溶液中具有 84.6 mg/g 的高盐吸附容量（SAC），是 rGO/NF 的 2.23 倍。海水淡化的高性能可归因于双电层电容和赝电容的形成。20 个循环后，rGO/CNF-1.5 电极的 SAC 保持在 77.1 mg/g，超过原始 SAC 的 91%。