Novel MoS2/NOMC electrodes with enhanced capacitive deionization performances

Abstract

Capacitive deionization (CDI) is a promising technology for seawater and brackish water desalination but still suffers from several drawbacks, such as low electrosorption capacity and less efficient desalination performance. In this study, MoS2/NOMC (nitrogen-doped highly ordered mesoporous carbon) composite with enhanced hydrophilicity, conductivity and capacitance was successfully synthesized by a hydrothermal process. The MoS2/NOMC electrodes showed efficient desalination performances with an electrosorption capacity of 28.82 mg/g at 1.6 V in 250 mg/L NaCl solution and a maximum electrosorption capacity of 30.49 mg/g based on Langmuir fitting. The mechanism of the enhanced desalination performance of MoS2/NOMC electrodes was explored through the characterization of the contributions of the capacitor-controlled (electrical double layer capacitor without charge transfer) and diffusion-controlled processes (charge transfer with N-doping of NOMC as well as the various oxidation states (from + 2 to + 6) of molybdenum atoms (Mo) in MoS2). Capacitor-controlled process played a major role (with the contribution of 73.17%) for the improved desalination performances of MoS2/NOMC electrodes compared to the diffusion-controlled process (with the contribution of 26.83%). In addition, MoS2/NOMC electrodes showed an excellent regeneration performance, indicating the potential of MoS2/NOMC composite as a promising CDI electrode material.