In this study, we report the synthesis of two CdS@TiO$_2$ nanocomposites (CT1 and CT2) by two-step low temperature solvothermal decomposition method using two different stoichiometric combinations between CdS and TiO$_2$ nanoparticles (NPs). CdCl$_2$(3-chlorobenzaldehyde thiosemicarbazone)$_2$ was used as a molecular precursor to obtain CdSNPs, whereas titanium isopropoxide was used to obtain TiO$_2$ NPs. The as-prepared CT nanocomposites were characterizedby powder X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy to evaluate their structures and properties. Further, these nanocomposites were used for the photocatalytic degradation of rhodamine B under solar light irradiation. It is found thatCdS@TiO$_2$ (CT1) nanocomposite shows highest degradation efficiency of 98.74% within 60 min as compared to bare TiO$_2$ NPs which shows only 66.40% degradation efficiency. The enhanced photocatalytic efficiency due to charge transfer properties of bare NPs and CT nanocomposites was further investigated by electrochemical analysis and photoluminescencestudies.

This work comprises a facile synthesis of cerium dioxide nanoparticles (CeO$_2$ NPs) using hydrothermal method. The characterization of the CeO$_2$ NPs was carried out using different techniques such as powder X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy and ultra-violet visible spectroscopy. The photocatalytic activity of the CeO$_2$ NPs was evaluated for the degradation of methylene blue under the sunlight irradiation. CeO$_2$ NPs, nanosphere obtained by the hydrothermal decomposition showed the highest photocatalytic efficiency (74.04%) due to their nanosize. Electrochemical impedance spectroscopy, galvanostatic charge/ discharge and cyclic voltammetry were used to examine the electrochemical properties of the electrode prepared using CeO$_2$ nanoparticles. The CeO$_2$ nanoparticles showed a specific capacitance of 91.75 F g$^{-1}$ at a current density of 1 A g$^{-1}$.