Single- and Few-Layers MoSe2 Nanoflowers: Synthesis, Characterization, and Their Piezoresponse

Abstract

We demonstrate a hydrothermal process at temperature of 180oC to synthesize a single to few layers MoSe2 nanoflowers which exhibit a high surface-to-volume ratio and is stable under room temperature in ambient air. The crystal structure of the MoSe2 nanoflowers has been confirmed by X-ray diffraction pattern, Raman, and High-resolution transmission electron microscopy (HRTEM). On the basis of the scanning electron microscope (SEM) image, the size of the MoSe2 nanoflowers is in the range of the 300-500nm. HRTEM image reveals that the MoSe2 nanoflowers possess a great number of the single- and few-layers, which further confirms that our nanoflowers display the plentiful amount of active surface sites. In addition, the lattice fringes between each single layer is about 0.66 nm, which is slightly larger than the reported value of 0.62 nm for the MoSe2. The piezoresponse force microscopy image further shows that the MoSe2 nanoflowers exhibits significantly piezoelectric potential which is generated from the active surface sites of the petals in the MoSe2 nanoflowers. Reference[1-6] 1. Duerloo, K.-A.N., M.T. Ong, and E.J. Reed, Intrinsic piezoelectricity in two-dimensional materials. The Journal of Physical Chemistry Letters, 2012. 3(19): p. 2871-2876. 2. Kaasbjerg, K., K.S. Thygesen, and A.-P. Jauho, Acoustic phonon limited mobility in two-dimensional semiconductors: Deformation potential and piezoelectric scattering in monolayer MoS 2 from first principles. Physical Review B, 2013. 87(23): p. 235312. 3. Alyörük, M.M., et al., Promising Piezoelectric Performance of Single Layer Transition-Metal Dichalcogenides and Dioxides. The Journal of Physical Chemistry C, 2015. 119(40): p. 23231-23237. 4. Qi, J., et al., Piezoelectric effect in chemical vapour deposition-grown atomic-monolayer triangular molybdenum disulfide piezotronics. Nature communications, 2015. 6. 5. Wu, T. and H. Zhang, Piezoelectricity in Two ‐ Dimensional Materials. Angewandte Chemie International Edition, 2015. 54(15): p. 4432-4434. 6. Chhowalla, M., et al., The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. Nature chemistry, 2013. 5(4): p. 263-275.