Manganese doping strategy for enhanced capacitive deionization performance of MoS2

Molybdenum disulfide (MoS2) has gained enormous attention as the electrode for capacitive deionization (CDI) by virtue of its fascinating layer structure and ion storage property. However, the sluggish intrinsic conductivity and limited ion storage capacity of MoS2 hampered their practical applications. In this work, a manganese doping strategy via a one-step hydrothermal process was adopted to fabricate manganese-doped MoS2 nanosheets (Mn-MoS2) for efficient capacitive desalination. It is shown that Mn-MoS2 presents an enlarged interlamellar spacing, enriched mesoporous structure, and excellent hydrophilicity. When used as a working electrode in a hybrid CDI cell, Mn-MoS2 delivered an outstanding salt removal capacity of 24.5 mg g-1 in a 500 mg L-1 NaCl solution. Notably, Mn-MoS2 presented fast kinetics in the desalination process, which reached equilibrium in 8 minutes with a removal rate of 3.06 mg g-1 min-1 and superior stability after 30 cycles, which outperformed the performance of most MoS2 based CDI electrode. XPS spectra indicated that the electronic structure of MoS2 could be modulated by Mn doping to generate 1 T phase, which further improved the intrinsic activity and ion storage capacity. This study paves a way for the design of MoS2 and its application in outstanding performance and durable CDI cell.