In this work, the effect of core size on the fluorescence emission properties of CdTe@CdS core@shell quantum dots was investigated under the condition of different shell thickness and pH values. Both CdTe and CdTe@CdS core@shell QDs were synthesized in aqueous phase by a simple method, whose optical features were characterized by absorption and fluorescence spectra . High resolution transmission electron microscopy (HRTEM) and X-Ray Diffraction (XRD) were utilized to study the structure and composition of the as-prepared QDs. We can conclude that a smaller initial core exhibits a greater potential for optimizing both fluorescence intensity enhancement and red shift. What's more, there is an optimal shell thickness for the strongest fluorescence intensity while a thicker shell contributes to a larger fluorescence red shift. The optimal pH value is 10.5 for the fluorescence intensity enhancement of the core@shell QDs and a higher pH value is an advantage to expedite the growth rate of CdS shell.
Wen Liu,Shuwen Liu,Peiyuan Zhang,Long Li,Zhangpeng Li,Jinqing Wang
Solvent-free nanofluids (NFs) based on a variety of lubrication core materials have attracted extensive attention in tribology, but it is still an open field to explore the relationship between size of core and tribological properties of NFs. In this paper, the multi-layer, ultrathin and ultrafine layered double hydroxides solvent-free nanofluids (ML-LDH-NFs, UT-LDH-NFs and UF-LDH-NFs) are proposed for lubricant. Compared with UT-LDH-NFs, ML-LDH-NFs exhibit better friction reduction and wear resistance performance for the interlayer sliding in multi-layer layered double hydroxides, UF-LDH-NFs with smaller lateral size is easier to slip into the sliding interface to form tribofilm, and thus provide more effective friction-reducing and anti-wear. This research provides fundamental insights into size effects of core materials for solvent-free nanofluids lubricants.
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