Capacitive Deionization Behavior Of ZIF-8 Coupling Graphene-derived Nitrogen-doped Porous Carbon And Walnut Shell-derived Porous Carbon

Desalination of seawater and reuse of saline wastewater can effectively solve the shortage of water resources.However,the existing methods often need to consume a lot of energy at the expense of high cost.Capacitive deionization（CDI）technology is a green water treatment desalination technology that does not require any additional reagents,and only needs to provide a working voltage of no more than 2 V to remove salt substances in the solution by the action of an electric field.CDI technology has the obvious advantages of simple operation,excellent effect,environmental protection and low carbon.In order to improve the performance of CDI,excellent electrode materials must be constructed.Carbon-based materials are considered to be the most ideal electrode materials due to their good electrical conductivity.This paper constructs the preparation of a new CDI electrode material based on two different substrates,and systematically analyzes its structure and electrochemical performance.The main research contents are as follows:（1）Using Zeolitic Imidazolate Framework-8（ZIF-8）and graphene oxide（GO）as raw materials,a method for preparing nitrogen-doped nanoporous carbon/porous graphene（GZ8PN）is proposed.In this work,due to the interaction between Zn²⁺and oxygen-containing functional groups on the GO surface,ZIF-8 can grow in situ on the GO surface,and then undergo high temperature and KOH activation to obtain nitrogen-doped nanoporous carbon/porous graphene.Not only that,but also systematically compared the electrochemical performance differences between materials with different GO contents and analyzed the reasons.GZ8PN’s high specific surface area（1426.32 m²/g）,high carbon content and rich mesoporous structure provide huge advantages for electrochemical performance and capacitive deionization performance.In capacitive deionization applications,a 250 mg/L Na Cl solution has a high adsorption capacity of 15.71 mg/g（1.4 V）.In addition,GZ8PN also showed good cycle stability in a lower Na Cl solution,with a cycle efficiency higher than 89.1%.（2）Using the living waste biomass carbon-walnut shell as raw material,biomass porous carbon is obtained through different activators.In this work,using different activation mechanisms of different activators,the biomass carbon skeleton was reconstructed,and carbon-based materials with high specific surface area were obtained through activation.SEM showed that the activated material has a three-dimensional honeycomb structure.Among all materials,KOH-C has a specific surface area of 1600.34 m²/g and a cumulative pore volume of 0.3561cm³/g,which provides favorable conditions for ion storage.Its specific capacitance is 106.23F/g.In capacitive deionization applications,it has good removal of different substances and good regeneration.