Formation of MoO3 and WO3 nanoscrolls from MoS2 and WS2 with atmospheric air plasma

Nanostructured transition metal oxides (TMOs) have intriguing electrochemical and physical properties that make them useful in a variety of electrochemical applications. Here, we report the synthesis of MoO3 and WO3 nanoscrolls from atomically thin layers of two-dimensional (2D) MoS2 and WS2 with atmospheric air plasma treatment. These structures with rolled layers have an increased surface-to-volume ratio and are promising for electrochemical applications. The morphology of the nanoscrolls is characterized by atomic force microscopy (AFM), while X-ray photoelectron spectroscopy (XPS) measurements confirm the formation of MoO3 from MoS2. Control experiments with a plasma generated from a mixture of N2/O2/H2O gases MoS2 suggest that the rolling mechanism is due to a combination of factors including oxide formation, stresses due to bonding changes, defects in the initial 2D material, and interplanar forces.