Efficient capacitive deionization of N-doped g-C3N4 quantum dots modified carbon cloth electrode under alkaline conditions

The desalination method in challenging pH environments is of great significance for the urgent problem of water scarcity. Therefore, the construction of high-performance stable electrode materials for capacitive deionization faces challenges under extreme pH conditions. This study is based on the self-assembly of low-cost raw materials and nanotube fracture, synthesizing nitrogen doped carbon nitride quantum dots (NCNQDs) with higher stability and charge transfer ability at pH > 10. The characterization results confirmed that the charge transfer resistance of NCNQDs is lower than that of nanotube structures, and the electrochemical testing of NCNQDs exhibited good specific capacitance (459.60 F g(-1)). Under challenging pH conditions, NCNQDs exhibited excellent desalination ability (74.89 mg g(-1), pH = 12) and extremely fast desalination rate (5 min, 68.82 mg g(-1)). Density functional theory was further used to verify the stability of NCNQDs and the effective sites for surface charge transfer, confirming that the adsorption activity of different nitrogen doped sites on NCNQDs varies. Theoretical calculations indicated that the electron transfer ability and stability of NCNQD made significant contributions to capacitive deionization. Characterization, experimentation, and theory jointly demonstrated the inherent potential of quantum dot materials for seawater desalination, providing a reference for researchers to design stable and efficient desalination materials.