Oxygen-incorporated molybdenum disulfide nanosheets as electrode for enhanced capacitive deionization

Molybdenum disulfide (MoS2) has emerged as a promising electrode for capacitive deionization (CDI) process. Increasing intrinsic conductivity of MoS2 is critical for further improvement of CDI performance. In this work, the effects of oxygen incorporation in MoS2 nanosheets on CDI performance were investigated. High-electronegative oxygen heteroatom incorporation into MoS2 nanosheets was realized via a facile hydrothermal method. The oxygen-incorporated MoS2 generated a dramatically improved CDI performance compared to pristine MoS2 nanosheets. The optimized MoS2 electrode with moderate degree of oxygen incorporation (2.91 at.%) exhibited the highest desalination capacity of 28.85 mg/g in 500 mg/L NaCl solution. The enhancement was found that oxygen incorporation could effectively improve the intrinsic conductivity and expose more active sites, leading to a higher specific capacitance and lower inner resistance. Besides, the oxygen-incorporated MoS2 with achieved balance between structure and active sites could reach the highest desalination capacity. This finding indicated that heteroatom incorporation into MoS2 could be a new way to enhance CDI performance.