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A simple hydrothermal method is developed for the synthesis of high-quality type II core-shell CdSe/CdTe quantum dots (QDs). The XRD results reveal the formation of mixed phases of CdSe and CdTe with a grain size of 12.6 nm. SEM morphology confirms the uniformly distributed nanoscale CdSe/CdTe with no agglomeration. EDX confirms the elemental presence of Cd, Se, and Te in the compound. TEM results suggest that the size of spherical CdSe/CdTe core-shell QDs is in the range of 8~10 nm. Significant results of the SAED pattern confirm the core and shell components as CdSe and CdTe, respectively. The correlation between the synthesis procedures and the corresponding structures of the core-shell CdSe/CdTe QDs is discussed. The demonstrated monodispersed lattice structure of core-shell CdSe/CdTe QDs has excellent PL emission properties at λ emi ~ 585 nm which is suitable for photovoltaic applications. The UV-Vis absorption bands at 455 nm and 560 nm confirm exciton emission due to the type II matrix of CdSe/CdTe QDs. [ABSTRACT FROM AUTHOR]

Various approaches to improve the efficiency of Lithium ion batteries (LiB) by using Si have been suggested because Si has the highest known lithium capacity. Although Si is more than ten times higher capacity than existing graphite anodes, Si anodes have limited applications due to its high volume change during cycling. Here we demonstrated graphene/Si-CuO quantum dots (Gr/Si-CuO QD) layered structure as an efficient LiB anode which prevents large volume expansion of Si due to the presence of CuO-Cu3Si. By Electrophoresis Deposition technique, the multi-layer of graphene and Si-CuO QD has been successfully fabricated followed by annealing process to form Cu3Si interlayer as confirmed by High Resolution Transmission Electron Microscope-Energy Dispersive Spectroscopy, X-ray diffraction and Raman analyses. The annealed Gr/Si-CuO QD exhibit the initial gravimetric specific capacity of 2869mAhg-¹ which is five times higher than that of annealed graphene at 0.5C. After 100 cycles at 1C rate the capacity retains ~71% and the excellent rate capability even at high C rate reveals controlled volume expansion owing to the multi layered architecture and the Cu3Si inter layer. The layered structure of Gr/Si-CuO QD electrode could be applied in next generation micro power sources. [ABSTRACT FROM AUTHOR]