Synthesis and characterization of single- and few-layer mica nanosheets by the microwave-assisted solvothermal approach

We have successfully fabricated single- and few-layer mica nanosheets, by means of using a solvothermal method in conjunction with a microwave irradiated expansion process. In the solvothermal process, dissolved potassium ions were intercalated onto the interlayer space of the mica. Following this, microwave irradiation facilitates the exfoliation of individual nanosheets. The synthesized products were characterized by field emission scanning electron microscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy measurements. AFM and TEM studies claimed the existence of single-layer mica. High-resolution TEM (HR-TEM) investigations revealed that the exfoliated product corresponded to a crystalline mica structure, being comprised of Si, Al, O, and K elements. XPS spectra exhibited the major constituent peaks, including O 1s, Si 2p, Al 2p, and K 2p. In addition, C atomic concentration has been slightly increased by the contamination during exfoliation, presumably due to the increase of the exposed mica surface. The C 1s XPS spectra revealed that the C–C bonding in organic surface contaminants was broken, whereas the Si–C bonding was enhanced, by the exfoliation process. The O 1s XPS spectra revealed that the Si–O bonding in mica was broken, generating the O–Si–C bonding. This study paves the way towards the fabrication of single- or few-layer inorganic nanosheets of desired materials, via a convenient and efficient route.