科研之友
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摘要
Molybdenum disulfide, which is composed of a monolayer or few layers, is a new kind of two-dimensional materials following the study of grapheme. It is a kind of direct band-gap semiconductor with excellent photoelectric properties, which has attracted much attention. In this paper, molybdenum disulfide with different particle size was successfully prepared by heat-up method. The MoCl5 was reacted with L-cysteine in the presence of oleylamine at 220 degrees C, and we performed different reaction time from 1 to 5 h to understand the formation mechanism. There are two mechanisms occurred in the formation process of MoS2 nanodots: one is the Ostwald ripening and the other is an epitaxial growth. Until there are no enough nuclei for growth, the size remains unchanged regardless of the growth of the time. The prepared MoS2 nanodots are homogeneous in the aspects of size and height from the large range due to the protection of OLA. In addition, OLA providing a strong reductive environment reduces Mo5+ to Mo4+ and avoids oxidation of the nanoparticles, which integrated with L-cysteine to results in the formation of H2S. The molybdenum disulfide quantum dots prepared for 3 h had monolayer structure. We also investigate the photoluminescence behaviors of the materials to inquire the size effect. The fluorescence spectra and Raman spectra of three kinds of molybdenum disulfides were studied. It was found that when the particle size or the excitation wavelength increased, the peak position of the fluorescence spectrum occurred red shift.
- 出版日期2017-5-10
- 单位南开大学
