Gold nanoparticles stabilized by thiolates derived from normal and ω-functionalized alkane-and arenethiols (HS(CH 2 ) n CH 3 , HS(CH 2 ) 10 COOH, HS(CH 2 ) 11 OH, HSC 6 H 4 NH 2 , HSCH 2 CH 2 C 6 H 5 , and HSCH 2 C 6 H 4 C(CH 3 ) 3 ) were synthesized. Differences in their chemical and ultrasonic stabilities were studied using UV-vis spectroscopy. The results showed that these stabilities of monolayer-protected nanoparticles were greatly influenced by the structure and functionality of the monolayer surrounding a nanoparticle core. The selective functionalization of the nanoparticle allowed us to prepare hybrid nanostructures (nanoparticle multilayer assemblies) with different compositions and functionalities. This paper also presents an investigation of the chemical, thermal, and ultrasonic treatments of these nanoparticle multilayer assemblies. The results suggest that the linkers used to build nanoparticle multilayer films govern the overall stability of hybrid nanostructures.

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Gadolinium oxide (Gd2O3) nanoparticles were prepared via the reaction of gadolinium nitrate hexahydrate (Gd (NO3)3·6H2O) and ethylamine (C2H5NH2), and their surface morphology, particle size, and properties were examined by using scanning electron microscopy, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet visible (UV-vis) spectroscopy. The Gd2O3 nanoparticles were used as the photocatalyst for the degradation of various azo dyes, such as methyl orange (MO), acid orange 7 (AO7), and acid yellow 23 (AY23) under irradiation with UV light. The effect of the experimental parameters (initial concentration of azo dyes, dosage of catalyst, and wavelength of UV light) on the photocatalytic properties of the Gd2O3 nanoparticles were investigated. At a constant H2O2 concentration, the photocatalytic degradation efficiency of the Gd2O3 nanoparticles for various azo dyes was in the order: methyl orange > acid orange 7 > acid yellow 23. The kinetics study showed that the photocatalytic degradation of azo dyes was followed by a pseudo first-order reaction rate law.