To ensure the safety of industrial and domestic water supply, desalination technology has attracted the attention of many researchers. This concept of “electrochemical desalination” was put forward by Evans and Hamilton [90]. Compared with reverse osmosis (RO) and multi-stage flash (MSF), the electrosorption desalination technology shows low energy consumption, easy operation, and so on. To improve the electrosorption desalination ability of graphene, Ahmed’s group prepared graphene/SnO2 NPs composite materials by microwave method as CDI electrodes, and this ability was significantly better than that of original graphene [91]. In addition, Zhang et al. prepared graphene/carbon aerogels (GCCAs), which achieved the best salt adsorption capacity (SAC) of 26.9 mg/g under the condition of 500 mg/L NaCl [92]. Furthermore, carbon aerogels were also prepared by carbonizing the composite of PANI and GO, whose adsorption capacity was 15.7 mg/g under the conditions of 500 mg/L NaCl and 1.2 V applied voltage [93]. Wang’s group prepared graphite porous carbon nanosheets (GPCSs) by activating and graphitizing straw waste as the electrode material, and the electrosorption capacity of the sample for 500 mg/L NaCl solution is 19.3 mg/g when 1.2 V voltage was applied [94]. Due to the low cost of biomass derivatives, Lu’s team synthesized porous carbon nanoflakes (PCNs) by using xylose as the carbon source through the carbonization, and the maximum SAC of PCNS CDI electrode for 1000 mg/L NaCl solution reached to 16.29 mg/g when the voltage of 1.2 V was applied [95]. Additionally, Li et al. obtained phosphorus (P)-doped carbon nanofiber aerogel (P-CNFA) by using bacterial cellulose as the raw material via freeze-drying and heat treatment, and the SAC of P-CNFA reached 16.20 mg/g for 1000 mg/L NaCl solution under working voltage of −1.2 V [96]. Therefore, we can infer that salt ions will be removed efficiently via electrosorption technology.

工业的快速发展导致重金属造成的水污染日益严重，不仅毒害水中的水生生物，而且危害人体健康。废水中重金属的传统处理方法主要包括化学沉淀，凝结  The rapid development of industry leads to the increasing water pollution caused by heavy metals, which not only poisons aquatic organisms in water, but also endangers human health. The traditional treatment methods for heavy metals in wastewater mainly include chemical precipitation, coagulation–flocculation, flotation, ion exchange, membrane filtration and - 絮凝，浮选，离子交换，膜过滤和吸附[97]。但是，上述方法有一些局限性。1997年，adsorption [97]. However, the above methods have some limitations. In 1997, Farmer等人利用电容法去除 et al. utilized the capacitive method to remove Cr。⁶⁺有效 efficiently [98]。随后，Oda的团队调查了. Subsequently, Oda’s group investigated the removal effect of Cu的去除效果。²⁺和锌 and Zn²⁺通过使用交流电极，然后成功地将 by using AC electrode, and then successfully introduced CDI技术引入重金属离子去除领域[99]。为研究表面改性对ACF布重金属离子吸附/电吸附容量的影响，黄等对 technology into the field of heavy metal ion removal [99]. To research the influences of surface modification on the capacity of ACF cloth for heavy metal ions adsorption/electrosorption, Huang et al. conducted the adsorption and electrosorption of Cu进行了吸附和电吸附。²⁺通过使用不同的改性 in wastewater by using different modified ACF布电极在废水中[100]。结果表明，电吸附的去除度是吸附的2.2倍。此外，戴氏研究小组使用AC作为电极，用于水溶液中As（III）的电吸附，并发现电吸附容量随着电压，初始As（III）浓度和pH值的增加而增加[101]。此外，黄氏小组调查了 cloth electrodes [100]. The results showed that the removal degree for the electrosorption was 2.2 times higher than that for the adsorption. In addition, Dai’s group used AC as an electrode for the electrosorption of As (III) in an aqueous solution, and found that the electrosorption capacity increased with the increase in voltage, initial As (III) concentration, and pH [101]. Furthermore, Huang’s group investigated the removal rate of Cd的去除率。²⁺铅, Pb²⁺和铬, and Cr³⁺以及通过使用 as well as the mixture by using CDI体系的混合物，发现电吸附能有效地除去这些金属离子，并且除去率与施加的电压呈正相关[102]。据我们所知，锰 system and found that the electrosorption can effectively remove these metal ions and the removal rate was positively correlated with the applied voltage [102]. To our knowledge, MnO₂/碳复合材料对废水中的重金属离子具有高吸附能力。因此，胡的小组准备了carbon composites have a high adsorption capacity for heavy metal ions in wastewater. Thus, Hu’s group prepared MnO。₂/CF复合材料经电镀法作为电吸附电极 composite materials via an electroplating method as the electrical adsorption electrode [103]。铜的吸附能力. The adsorption capacity of Cu²⁺对于锰 for MnO₂/CF复合电极在0.8 composite electrode reached V的工作电压下达到172.88 mg/g，是普通 under a working voltage of 0.8 V, which was more than two times for ordinary MnO的两倍以上₂在没有电场的情况下吸附剂。此外，刘和同事通过真空过滤工艺制造了活性炭布 adsorbent in the absence of an electric field. Moreover, Liu and co-workers fabricated activated carbon cloth/氧化石墨烯复合材料（graphene oxide composite (ACC/GO），用作CDI电极以去除) by vacuum filtration process, which was used as the CDI electrode to remove Co²⁺和水中的 and C。当对复合电极施加s⁺ in water. When 1.2 V电压时， voltage was applied to the composite electrode, the maximum adsorption capacity of Co的最大吸附容量⁺²⁺在 and CoCl的条件下，C和C可分别达到s⁺ can reach 16.7 mg/g / g和and 22.9 mg / g⁺/g, respectively, under the condition of the CoCl₂溶液浓度和 solution concentration and CsCl溶液浓度为20mg/L[67]。由于 solution concentration of 20 mg/L [67]. Due to the low cost and high capacitance of MnO的低成本和高电容₂，李氏组合成, Li’s group synthesized α-MnO₂纳米颗粒经水热法，结合碳纤维纸（ nanoparticles by the hydrothermal method, combined with carbon fiber paper (CFP），得到), to obtain α-MnO₂/CFP作为 as CDI电极材料[104]。结果表明，在相同电吸附条件下，复合材料的镍离子去除能力达到 electrode material [104]. The results show that the removal capacity of nickel ion for the composite reached 16.4 mg/g，是活性炭的两倍多。因此，CDI系统对不同金属离子和有害离子的电吸附行为表现出明显的差异。 more than twice that for activated carbon under the same electrosorption conditions. Therefore, the electrosorption behaviors for different metal ions and harmful ions by the CDI system exhibit an obvious difference.

由于农业的需求，该领域使用的各种除草剂和肥料都造成了水污染。此外，亚甲基蓝（  Due to the demand of the agriculture, various herbicides and fertilizers used in this field have caused water pollution. In addition, methylene blue (MB）、其他着色剂和尿素磷化合物广泛用于印染行业，这些有机物会对水环境造成破坏。因此，电吸附法还应用于废水中各种有机化合物的去除。Yue和同事们报道了一种), other colorants and urea phosphorus compounds are widely used in the printing and dyeing industry, and these organics will cause damage to the water environment. Therefore, the electrosorption method is also applied in the removal of various organic compounds in wastewater. Yue and co-workers reported a kind of rGO/SWCNTs薄膜作为去除MB的CDI电极（图5a–e）[105]。对于该系统，PS被用作模板，引入GO片材以产生大孔隙，并在薄膜之间分布单壁碳纳米管以产生有效的离子扩散途径。因此，当施加−1.2 V电压时， film as the CDI electrode for removing MB (Figure 5a–e) [105]. For this system, PS was used as a template to introduce GO sheets for creating large pores and SWCNTs were distributed between the films for generating efficient pathways of ion diffusion. Consequently, the maximum adsorption capacity of rGO/SWCNTs薄膜的最大吸附容量达到13， film reached to 13,014.3 mg/g，并且在五次循环后容量保持接近100%。此外，该组合成了多孔 when applying −1.2 V voltage, and the capacity retention kept nearly 100% after five recycles. Furthermore, this group synthesized porous MXene/SWCNTs薄膜作为CDI电极，用于去除废水中的有机染料（图5f–j），当施加−2.4 V电压时，最大吸附容量高达28， film as a CDI electrode for the removal of organic dyes in wastewater (Figure 5f–j), and the maximum adsorption capacity was as high as 28,403.7 mg/g [106]。此外，本研究小组制备了源自废烟过滤器/沸石-咪唑酸盐框架-8（ZIF-8）复合材料[6-10，107]的碳泡沫电极，发现当施加−1.2 V电压时，这些碳泡沫的最大电吸附容量MB达到 when applying −2.4 V voltage [106]. In addition, our group prepared carbon foam electrodes derived from waste cigarette filters/zeolitic-imidazolate frameworks-8 (ZIF-8) composites [6–10,107], and found that the maximum electrosorption capacity of MB for these carbon foams reached to 1846.7 mg/g。在大多数条件下，使用大多数水处理方法的甲基橙（MO）溶液的吸附时间超过1 h，而Liu及其同事使用一步水热法制备的多孔石墨烯水凝胶（R-HGH）作为CDI电极[108]。当对R-HGH施加0.6 V电压时， when applying −1.2 V voltage. Under most conditions, the adsorption time of methyl orange (MO) solution using most water treatment methods is more than 1 h. Whereas, Liu and co-workers used the holey graphene hydrogel (R-HGH) prepared by one-step hydrothermal method as the CDI electrode [108]. When 0.6 V voltage was applied to the R-HGH, the electrosorption capacity for 100 mg/L MO溶液的电吸附容量为 solution was 57 mg/g，吸附平衡时间可在200 s以内。因此，电吸附可以为去除典型的有机化合物提供有效的途径。, and the adsorption equilibrium time could be within 200 s. Therefore, electrosorption can provide an effective route for the removal of typical organic compounds.