Study on the production of molybdenum disulfide nanosheets-based materials using a Taylor-Couette flow reactor

Abstract

MoS$_2$ nanosheets have been used in various applications but their inert basal plane has limited the further use of MoS$_2$ nanosheets. Although attempts have been made to activate inert basal plane of MoS$_2$ nanosheets by phase transition, production of hole, or forming composite, processing of MoS$_2$ nanosheets usually needs additional chemical treatment. In this study, simple and economical production of MoS$_2$ nanosheets-based materials has been studied to minimize the complexity of the conventional methods.

Heat treatment and use of organic solvents are the major drawbacks in the conventional production of MoS$_2$ nanosheets-based materials. To resolve the problems, fast and simple hydrodynamic production of MoS$_2$ nanosheets-based materials was developed using a Taylor-Couette flow reactor. The high shear stress of the Taylor-Couette flow enabled exfoliation of pristine MoS$_2$ and induced phase transition from 2H-MoS$_2$ to 1T-MoS$_2$ which contains active basal plane. When additional LiCl aqueous solution was used, Li-ion desulfurized MoS$_2$ in the form of Li$_2$S and produced holes on basal plane of MoS$_2$ nanosheets, resulting in holey 1T/2H-MoS$_2$ nanosheets. Also, a fast and simple synthesis of Fe$_2$O$_3$@MoS$_2$ 0D/2D-nanocomposite material was developed. High shear stress and mixing characteristics of Taylor-Couette flow were used for exfoliation of MoS$_2$ and synthesis of uniform Fe$_2$O$_3$ nanoparticles on MoS$_2$ nanosheets, resulting in a Fe$_2$O$_3$@MoS$_2$ in the form of 0D/2D-nanocomposite material.

To demonstrate that the basal plane of MoS$_2$ nanosheets-based materials has chemical activity for the adsorption, both MoS$_2$ nanosheets-based materials were applied to the removal of ionic dyes by adsorption, and holey 1T/2H-MoS$_2$ nanosheets and Fe$_2$O$_3$@MoS$_2$ nanocomopiste showed higher adsorption capacity for methylene blue and methyl orange, respectively, compared to that of previously reported MoS$_2$-based adsorbents. Presented one-step hydrodynamic production of MoS$_2$ nanosheets-based materials would be a better option to produce MoS$_2$ nanosheets-based materials economically for various applications.