Capacitive deionization of high N-doping carbon nanocages preparedby chemical vapor deposition

field force. It has great potential in brine pre-concentration and reducing the energy consumption of zero liquid discharge desalination.However, the current CDI technology is limited by the low electro-adsorption active sites and uncontrollable pore structure distribution ofporous carbon electrodes, resulting in low desalination capacity and charge efficiency, which hinders its further application. Therefore,highly active surfaces and structurally controllable N-doped carbon nanocages (N-CNC) were constructed by a chemical vapor deposition method using pyridine as a carbon source and alkaline magnesium carbonate as a templating agent to investigate their desalinationproperties. Through precise control of the carrier gas and pyridine quantities, the resulting N-CNC consists of 3- 5 layers of graphitized carbon arranged in a hollow rectangular morphology. The average thickness of the outer wall ranges from 1 to 2 nm, with an impressive N content reaching up to 4.2%. Benefitting from its exceptional porous structure distribution and rich surface chemistry, N-CNC exhibits electrochemical behavior primarily contributed by its pseudo-capacitive properties. The desalination test results of the assembled N-CNC/ / N-CNC symmetric module using the single-pass desalination mode show that the salt adsorption capacity and charge efficiency are21.8 mg/ g and 82%, respectively, with low energy consumption of 0.71 Wh/ g. Further treatment of coal chemical high-salinity water testshow excellent anion absorption performance. Electric adsorption desalination capacity of Cl,SO ,NO are 33.4,20.5,8.9 mg/ g,of which theselectivity ratio of Cl / SO is as high as 5.1. This study provides a simple and controllable preparation method for N-doped carbon nanocagestructure, which provides certain theoretical and technical support for the industrialization application of CDI concentrated industrial brine.