Boosting ion uptake and electron transport through bridging Na2MnSiO4 with acidified carbon nanotubes for enhanced hybrid capacitance deionization

Abstract

The enhancement of ion uptake capacity and electron transport process in the hybrid capacitive deionization (HCDI) Faraday electrode material is achieved by bridging Na₂MnSiO₄ (NMS) with acidified carbon nanotubes (HCNT). Herein, NMS@HCNT composites with three-dimensional conductive network structure were synthesized by the sol–gel method and subsequent thermal treatment. The NMS@HCNT Faraday electrode material displayed a high desalination capacity of 52.84 mg/g and a satisfactory mean salt adsorption rate of 6.89 mg/g min⁻¹, which are significantly higher than the desalination capacity (30.06 mg/g) and mean salt adsorption rate (4.35 mg/g min⁻¹) of NMS. This excellent desalination performance is mainly attributed to the fact that HCNT in the NMS@HCNT material not only acts as a highway for electron transport, but also increases the specific surface area of the material, which provide more ion-accessible surfaces and active sites to facilitate charge transfer and ion uptake capacity during desalination, thus effectively enhancing the HCDI performance of the electrode material. This study offers valuable insights into the design of HCDI electrode materials for high-efficiency desalination.