Defect engineering of porous PZN@CF nanosheets with accelerated reaction kinetics for high performance dechloridation

Suffering from the slow ion diffusion kinetics and insufficient surface reactivity, transition metal hydroxide (TMH) electrodes exist the problem of low desalination capacity and low desalination rate. Different from the traditional modification strategy of simply expanding the specific surface area, the collaborative optimization strategy of defect engineering and structure can effectively address the above chanllenge. In this study, the phosphate-functionalized porous ZnNiOH nanosheet array electrodes (PZN@CF) were designed and prepared. A hierarchical porous structure was constructed by Kirkendall effe-induced directional etching to shorten the ion transport path. At the same time, phosphate-rich defect sites were introduced by phosphate ion surface modification to form a highly active P– O –Zn/Ni bonding interface, which significantly improved the charge storage capacity of the electrode and the adsorption kinetics of Cl − . The electrode material combined high specific surface area (35.873 ​m 2 ​g −1 ) (increased by 4–9 times) and excellent chemical stability with ultra-high specific capacity of 263 ​mA ​m −2 . The CDI system of PZN@CF achieved excellent capacity of 151.23 ​mg ​g −1 at 1.6 ​V and rapid removal rate of 6.07 ​mg ​g −1 min −1 . Our strategy can be further extended to the modification of other layered metal compounds, through specific functional groups directed modification, to achieve the precise balance of "defect-activity-stability", providing a common path for the design of highly selective ion trapping materials.